***Useful Information for Apprentices***

[reedsinthewater]

I've printed all the info and I'll happily share at college with those who are interested

 

[amberleaf]

Impedance of supply :
Voltage falls with an increase in current ( 230V . 40A flows )

Thus Zs system volt drop . 230 228 --- 40 = 2Ω --- 40 = Ohms
Answer : 230 sub 228Ω = 2 ÷ 40 = 0.05Ω
Then : PSSC = Uo2 --- Zs = 230 --- 0.05 Ωs ( 230 ÷ 0.05 = 4600 )
PSSC = Uo2 230 ÷ 0.05 = 4600Amps or 4600kW ,
230 sub 228 = 2 ÷ 40 = 0.05 . ( PSSC = Uo 230 ÷ 0.05 = 46Amps )

 

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Fuses are placed in a circuit to act as a weak point which will melt if things get too hot. This stops fires happening after a cable overheats or an appliance explodes. If the current flowing through a cable is too great for either the size of the cable , or the appliance it is feeding, something has to give....The idea is the fuse will go first....., its important the right fuse is put in !

A normal house hold fuse is rated at 13 amps. An amp, short for ampere is a unit of electrical current. An electrical appliance needs to have electricity flowing to it to work. How much electricity it needs to work, is measured in amps. It is very important to know how many amps each piece of electrical equipment in your home draws from the power supply because there is only a finite amount of power available before things start to cook!

If you know how many amps an appliance needs, you know which part of the system to get the electricity from and which fuses to apply and which cables and wires to use to stop it, the fuses or wires overloading or overheating.
To work out how many amps an appliance needs to draw from the supply you need to know the Wattage of the appliance. A watt is the way of measuring the rate at which an appliance uses the power available to it.
Appliances, even light bulbs , are marked with a Wattage. To stop the numbers getting too big, 1000 Watts equals
1 kiloWatt. ( Watt being the name of the guy who sorted it all out in the first place). To find out what size fuse to use to protect an appliance you need to know the wattage and the voltage available. Most homes in the UK are served by a 230 volt supply. The super speedy fast kettle we have in the office is rated at 2500 - 3000 Watts.(2.5 -3kW) We must take the larger figure for safety. 3000 kwatts’ is then divided by the voltage to give us the current rating of the cable and fuse. ( 3000kW ÷ by 230 = 13.04amps. )

As 3000 Watts is the maximum it is safe to put a 13amp fuse in the plug. The cable size is determined by looking at our other projects. This is how amps are worked out. If you know how many amps are available, e.g. you have a fuse, MCB or RCD in your consumer unit but you are unsure of what you can put on this circuit, you can do the calculation the other way round. Multiply the voltage by the amps and this will give you the maximum number of Watts you can place on the circuit.

If your lighting circuit at home is protected by a typical 5 amp fuse you can multiply this by the voltage to get 1150 Watts. Now you can work out how many bulbs, and of what size, it is safe to have in your fittings. For low voltage lighting see another project. ( 230V ÷ 5A = 1150Watts )

A cooker circuit is slightly different from this however. Should you be trying to work out the size of cooker you can buy, a cooker, of 12kW or 12,000 Watts, with all rings blazing and the oven and grill firing out juicy steaks can potentially use a whole shed full of electric and should need a 52amp fuse to protect it . ( 12,000kW ÷ by 230volts = 52amps )
Cookers : 12000kW . ( 12000 ÷ 230 = 52A ) Ib = P = 12000 . ( Ib = P/12000 --- U/230 = 52A ) first 10Amp : = 42Amp ← ( 42 x 30% = 12.60 ) ↔ ( first 10Amp + 12.60 + 5 = 27.6Amp ) Allowance for socket outlet / 5 Amp : Actual circuit current 12.6Amps : Without socket-outlet 22.6Amps . ( * Protective Device 32Amps * ) ←

But, the chances of all every part of the cooker being on at one time are very small and a principle, called The Diversity Principle, is applied to the cooker circuit. For the diversity principle to be understood you must assume that the first 10 amps of current are always needed by the cooker. Probably only 30% of the remaining, available current will be used at any one time however. The actual demand will then be, 10 amps (used all the time) added to 30% of the remaining 42amps (= 13amps) making a total of 23 amps. If the cooker control unit has a 13 amp socket as well as the cooker switch ( another 5 amps must be added, making 28 amps. It would then be appropriate to place the cooker on a 30 or 32 amp circuit :

• Cables are used for different applications because they are differing thicknesses and can cope with differing currents safely with differing amounts of electrical resistance. A simple way to explain resistance is to see it as electrical friction. The cable will slow down some of the energy in the current. This means a little less current will reach the target than was actually sent.

Electric cookers, electric showers and Immersion heaters use a great deal of current and therefore require thicker cables. If a cable is too thin for the job it is being asked to do, it will get too hot and catch fire. Generally it can be said that any cable carrying current to an appliance that is intended to produce heat will have a bigger current rating and bigger cable.

Also to be taken into consideration is the distance of the appliance from the electrical source. The greater the distance, the greater the resistance and the less current that will be available at the other end.
Cables must be placed in a situation where they will not be overheated. If cables are run in a loft they must not be placed under insulation and if they are run in insulated walls they will carry a different rating. Please check the tables below :

The tables below show two different cable and amp ratings. The first table is for cables installed by what is known as Method 4. This is cables enclosed in an insulated wall. The second table is for cables fixed using method 1.2 . This is called clipped direct.

Table : Cables enclosed in an conduit in an insulated wall: Method 7 : Regs : 4D5 / p-282 . Cable size : 1mm : Rating in Amps 11.5 : 1.5mm : 14.5A : 2.5mm : 20A 4.00mm : 26A : 6.00mm : 32A : 10.00mm : 44A :

Table 4D5 - 70°C : Cables which are clipped direct: Method C method - 6 : Cable size : 1mm : Rating in Amps 16 : 1.5mm : 20 A : 2.5mm : 27A : 4mm : 37A : 6mm : 47A : 10mm : 64A : 16mm : 85A :

 

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A current of 8A flows in an A.C. magnet circuit connected to a 230V supply .
( Determine the impedance of the magnet coil )
U = I x Z ( 230V = 8A x Z ) 230 ÷ 8 = 28.75
Z = 230 --- 8 = 28.75Ω

Percentages & Efficiency
Efficiency : the output of a generator ( 1500W ) 1500 ÷ 1900 = 0.789.
The intake is equivalent to ( 1900W ) 0.789 x 100 = 78.9%
Percentage efficiency : ( 78.9%

Efficiency of Motor loading :
Motor produces output power ( 2000W ) 2000 ÷ 2800 = 0.714.
Electrical input ( 2800W ) 0.714 x 100 = 71.4%
Efficiency of motor at loading : = % = 71.4%

Determine Percentages Efficiency of Generator
The power output from a generator is ( 2600W ) 2600 ÷ 3500 = 0.742
The power required to drive it is equivalent to ( 3500W ) 0.742 x 100 = 74.2%

Determine Percentage voltage drop : 400 – 385V ---- 400 x 100 ( 400 sub 385 = 15. )
( 15 ---- 400 x 100 ) 15 ÷ 100 = 0.15 ↔ 0.15 ÷ 400 = 3.7%

Calculate percentage volt drop :
The voltage at the terminals of a motor is 223V ( 223 sub 230 = 7 ) ↔ 0.07 ÷ 230 = 3%

Power circuits :
A Ring final circuit :
In general domestic premises there should be a separate ring
Final circuit for every 100m2 of floor area. We must remember
That the maximum load that can be connected to a ring protected
By a 30A / 32A fuse is just over 7 kW, and the number of circuits Selected accordingly .

Power - DC Circuits : Watts = E x I Amps = W / E
E = Voltage / I = Amps / W = Watts

What is Power Factor ?
Power Factor is a characteristic of alternating current, and can be defined as the ratio of working power to total power.
Alternating current has the following components
* Real Power ( - Power which produces work ( kW )
* Available Power ( -Power delivered or total volt amps ( kVA )
* Reactive Power ( - Power needed to generate magnetic fields required for the operation of inductive electrical equipment. (kVAR) No useful work is performed with reactive power.
Therefore the unitless Power Factor is obtained from
* Power Factor = ( Real Power ----- Available Power = kW --- kVA

Power Factor is generally represented as a percentage or a decimal. Perfect power factor, often referred to as unity power factor would be 100% or 1.0.

What is Power Factor Correction ?
All flowing current causes losses in the supply and distribution system. A load with a power factor of 1.0 results is the most efficient loading for the supply and a load with a power factor of 0.6 will have much higher losses in the supply system. These loses have to be paid for, and result in higher utility bills. It is possible to modify the supply and distribution system to bring the power factor closer to unity. This is called power factor correction.

Correcting Power Factors
The simplest form of power factor correction, sometimes referred to as static correction, is by the addition of capacitors in parallel with the connected inductive load. The resulting capacitive current is a leading current and is used to cancel the lagging inductive current flowing from the supply. The capacitors can be applied at the starter, or the switchboard or at the distribution panel. Note that power factor correction should not be used when a motor is controlled by a variable speed drive.
Rather than correcting each individual load, the total current supplied to the distribution board can be monitored by a controller which switches capacitor banks to maintain the power factor at its predetermined setting. The controller switching in capacitors as new loads come on line, and switching out capacitors as loads go off line. This type of correction is sometimes referred to as bulk correction.

Common Inductive Loads
Commonly used electrical equipment that provide an inductive load include lighting circuits, heaters, arc welders, distribution transformers and electric motors.

 

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RCDs for protecting people have a rated tripping current (sensitivity) of not more than 30 milliamps (mA). Remember:

What is PUWER?
PUWER replaces the Provision and Use of Work Equipment Regulations 1992 and carries forward these existing requirements with a few changes and additions, for example the inspection of work equipment and specific new requirements for mobile work equipment. Many aspects of PUWER should therefore be familiar to you.

The Regulations require risks to people’s health and safety, from equipment that they use at work, to be prevented or controlled. In addition to the requirements of PUWER, lifting equipment is also subject to the requirements of the Lifting Operations and Lifting Equipment Regulations 1998.

Extension leads
The use of extension leads should be avoided where possible. If used, they should be tested as portable appliances. It is recommended that 3-core leads (including a protective earthing conductor) be used.

A standard 13 A 3-pin extension socket-outlet with a 2-core cable should never be used even if the appliance to be used is Class IT, as it would not provide protection against electric shock if used at any time with an item of Class I equipment.

Class III equipment
Equipment, for example for medical use, in which protection against electric shock relies on supply at SELV (Safety extra low voltage) and in which voltages higher than those of SELV are not generated. Class III equipment must be supplied from a safety isolating transformer.

Portable Appliance Testing ↔ (PAT) For Short !!!

The Dangers of Earth Leakage : Modern equipment causes a standing current in the protective earth conductor. This is not a fault, but a functional requirement of the equipment. Because of this standing current earth integrity becomes very important; when a fault develops the voltage on exposed metal work will rise to half the supply voltage with possibly lethal consequences.

* For added safety trailing sockets should be used in conjunction with a residual current device (RCD).
Cable Plug Length ( 2 ) Cable Specification : 1.25mm2 <HAR> 3-core PVC insulated cable to BS 6500: 1994: Table 16/IEC227-5. Colour white. Standards and approvals : All 13A Duraplug trailing socket outlets comply with ** BS 1363/A: Part 2: 1995. ** ↔ Regulations / P/229 . ↔ Regulations / P/229 : Replacement fuses where fitted are to BS 1362 : Regulations / P/230 . BS 6500:2000 ( 2005 ) :

you should use the lowest value fuse depending on the wattage as described in The Electrical Equipment (Safety) Regulations so for a 900 watts fixture 3 amp is too small ,13 amp is too high and a 5 amp is just right.

Also don't forget to allow for the switch on surges which some equipment may exhibit, inductive loads such as those fitted with wound components such as transformers, motors and compressors will draw a lot of current at switch on. Ever seen the stage lights dim slightly when you turn on your amplifier? - well that’s as a result of the surge which it draws when the transformer is energised and the large internal psu smoothing caps charge.

Plug top fuses don't have the anti-surge capabilities of the 20mm glass / ceramic type fitted internally into the equipment which feature a little spiral or thicker points within the fuse wire in order to absorb the initial surge, and ordinary fuses can blow as a result of the surge if it is not accounted for. This is why most fridges will come with a 5A or 13A plug fuse in the moulded plug, even if the appliance is only rated at a few 100 watts

If you run several items from one 13a extension lead then always remember to switch on the connected equipment in a orderly manner. Leaving everything in the 'on' position as you throw the switch at the plug end could cause enough surge from several pieces of equipment all energizing together, to blow even a 13A fuse, and sometimes trip a venue RCD

It is vitally important that the flex is rated equal to or above that of the fuse. Otherwise you could have a 3A piece of flex connected to a 13A plug fitted with a 13A fuse. Whilst the current is below 3A the flex is fine, however if the load increases to 10A or even 13A, then the fuse still will not blow, however the 3A flex will be carrying three or four times its design current causing it to get very hot and eventually melt, possibly igniting any floor tiles of furnishings which it is in contact with, and you have a fire risk.

Bear in mind, that because of the design characteristics of fuses, it may be possible to draw a significantly higher current for a short period of time before the fuse finally gives up and fails. I've seen venues with toaster, deep fat fryer and a tea urn all plugged into one 13A 4 gang trailing socket Fair enough if they aren't all used at the same time, but the large brown spot appearing on the outside of the plastic casing stated otherwise, and yes it is possible to draw anything upto about 20A or 21A from a 13A plug top fuse for half an hour or so before the fuse will break, plenty of time to start a fire so a little common sense and mathematics is called for, where one lead may be powering an entire disco - don't think for one minute that the fuse will blow the moment you step over that 13A rating.

------- 3 METRE 4 WAY EXTENSION LEAD

Electrical Equipment (Safety) Regulations 1994 FAIL ( BS- in the UK )
Plugs and Sockets, etc. (Safety) Regulations 1994 FAIL
Failures include access to live parts, cover removable without tools, inadequate conductors (0.11mm ←←← as opposed to 1.25mm ←←← required ), inadequate cord anchorage, inadequate fuse and the product was labelled as 6 way socket, but was only 4 way!

UNKNOWN BRAND 10 METRE, 3 GANG CABLE REEL
Electrical Equipment (Safety) Regulations 1994 FAIL
Plugs and Sockets, etc. (Safety) Regulations 1994 FAIL
Failures include inadequate shutters on sockets, access to live parts, inadequate cable size, inadequate cord anchorage, inadequate fuse

 

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All emergency fittings should be regularly tested, they are normally installed with a test switch near by, which can only be operated by a special key. Each fitting should be inspected daily to check that the LED is on. Tested monthly to see they operate, and every 6 months they should be run for an hour. Every 3 years a full 3 hour duration test should be carried out, preferably until the batteries are run down completely. In this way the batteries which are sealed Nickel Cadmium can maintain a full charge, if you only partially discharge them they develop a "memory" and only part of their power is available. All emergency fittings should have a red LED which shows that the batteries are charged and ready for action, if the LED is not lit the batteries

 

[Stringbags]

I have copy/pasted a lot of the info that you have provided, my students are due for their 2330 unit 301 exam/gola soon and they will benefit from your contribution. thanks Amberleaf for taking the time to share.

Stringbags

 

[amberleaf]

Electrical safety - main guidance
if electrical equipment is unsafe or in a poor condition it could cause personal injury, workplace fires or even kill.
Electrical injury can arise from
• Electric shock
• Electric burns
• Fires of electrical origin

Inspecting and testing electrical equipment ( Pat Testing )
Inspecting and testing equipment involves action at three levels:-
• Checks by the user
• Formal visual inspections :by an appointed competent person or competent contractor
• Combined inspection and tests :by an appointed, competent person or competent contractor

In most cases, staff are likely to use their own equipment including computers and it is in their own interests to ensure it is in a good, safe condition.
They can do this by carrying out ( User Checks *** ) before they start work. : Ps this will come up a lot in -&- Q. Formal visual inspection

** For double-insulated equipment, breakdown is caused by physical damage 99 times out of
100, so visual inspections should identify this.
***If not in a high risk environment and not subject to abuse. If latter occurs then need to
carry out combined inspection and testing more frequently.

Where extension cables or extensions in drum reels are in use, ensure the equipment is not overloaded - check the information on the extension cable and ensure the required current in amps does not exceed the quoted figures. ( This is what -&- are looking for Q/As )

2.5mm2 – 25 metres
2.5mm2 – Extension Leads are too Large for Standard ( 13A ) plugs ,
Although they may be Used with BS-EN 60309 Industrial Plugs . Extension Leads exceeding the above Lengths should be Fitted with a ( 30mA RCD ) ←← a Must -&-
Manufactured to BS-7071 :

Regs : p/21 Class 111 Equipment : ( if in Doubt most of the time you’ll find it in Definitions ) Part 2 ,

Equipment in which protection against electric shock does not relay on basic insulation only .but in which additional safety precautions such as Supplementary Insulation are provided . there being No Provision for the Connection of Exposed Metalwork of the Equipment to a Protective Conductor . and No Reliance upon precautions to be taken in the fixed wiring of the installation ( see BS-EN 61140 )

Class 111 Equipment : Equipment in which protection against Electric Shock Relies on Supply at SELV and in which Voltages higher than those of SELV are Not Generated ( BS-EN 61140 )

‘powertrack system’ means an assembly of system components including a generally linear assembly of spaced and supported busbars by which accessories may be connected to an electrical supply at one or more points
( pre-determined or otherwise) along the powertrack. )

‘protective conductor’ means a conductor used for some measures of protection against electric shock and intended for connecting together any of the following parts:
(i) exposed conductive parts,
(ii) extraneous conductive parts,
(iii) main earthing terminal
(iv) earth electrode(s),
(v) the earthed point of the source, or an artificial neutral

‘SELV’ (Separated Extra-Low Voltage) means an extra-low voltage which is electrically separated from earth and from other systems in such a way that single fault cannot give rise to the risk of electric shock

‘short circuit current’ means an overcurrent resulting from a fault of negligible impedance between live conductors having a difference in potential under normal operating conditions

‘PELV (Protective Extra-Low Voltage)’ means an extra-low voltage system which is not electrically separated from earth, but which otherwise satisfies all the requirements for SELV

permit-to-work’ means an official form signed and issued by a responsible person to a person having the permission of the responsible person in charge of work to be carried out on any earthed electrical equipment for the purpose of making known to such person exactly what electrical equipment is dead, isolated from all live conductors, has been discharged, is connected to earth and on which it is safe to work

Protection
Mechanical protection includes the provision of barriers, enclosures . protective covers, guards and means of identification, the display of warning notices and the placing of equipment out of reach. Where it is necessary to remove barriers or open enclosures, protective
covers, guards, this should be possible only by use of a key or tool. ←← -&- Q/As in the Regs 17th

Every high voltage (H.V.) switchroom/substation, except when manned, should be kept locked. A duplicate key for each H.V. switchroom/substation should be available, for emergency purposes, in a key box at a designated location. All other keys for use in the H.V. switchroom/substation should be kept under the control of a responsible person.

Exceptionally, a key may be held by a person whose duties require him to have frequent access to an H.V. switchroom/substation. In
such a case, that person should obtain a written authorisation from the responsible person stating the duties for which the person is
required to hold the key

Arrangement of entrance/exit
At least one exit of a switchroom/substation should open outwards and this emergency exit should be identified clearly .

Conductors near the entrance/exit of a switchroom/substation must be so arranged or protected that there is no risk of accidental contact of any live metal by any person entering or leaving

In order to provide free and ready access at all times for the maintenance and operation of the electrical equipment contained in a switchroom/substation, every entrance/exit of a switchroom/ substation should be kept free of any obstruction including
** which impedes the access to the switchroom/substation from a public area

* ‘appliance’ means an item of current using equipment other than a luminaire or an independent motor or motorised drive.
* ‘appliance, fixed’ means an appliance which is fastened to a support or otherwise secured or placed at a specific location in normal use.
* ‘appliance, portable’ means an appliance which is or can easily be moved from one place to another when in normal use and while connected to the supply.
* ‘barrier’ means an effective means of physically preventing unauthorised approach to a source of danger.
* ‘basic protection’ means protection against dangers that may arise from direct contact with live parts of the installation
* ‘bonding’ means the permanent joining of metallic parts to form an electrically conductive path which will assure electrical continuity and has the capacity to conduct safely any current likely to be imposed.
* ‘bonding conductor’ means a protective conductor providing Main Protective bonding Conductor . Regs p/32
* ‘bunched’ means two or more cables to be contained within a single conduit, duct, ducting or trunking or, if not enclosed, are not separated from each other.
* ‘busbar trunking system’ means a type-tested assembly, in the form of an enclosed conductor system comprising solid conductors separated by insulating material. The assembly may consist of units such as expansion units, feeder units, tap-off units, bends, tees, etc. Busbar trunking system includes busduct system.
* ‘cable channel’ means an enclosure situated above or in the ground ventilated or closed, and having dimensions which do not permit the access of persons but allow access to the conductors and/or cables throughout their length during and after installation. A cable channel may or may not form part of the building construction.
* material, other than conduit or cable trunking, intended for the protection of cables which are drawn-in after erection of the ducting, but which is not specifically intended to form part of a building structure.

 

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‘dead’ means at or about ↔ Zero Voltage ← and disconnected from any live system.

* Good workmanship should be used in the construction and installation of every electrical installation * All materials chosen and used in an electrical installation should be purposely designed for the intended application and should not cause harmful effects to other equipment, undue fire risk or electrical hazard . * Special consideration should be given in choosing materials purposely designed for electrical installations which are :- (i) exposed to weather, water, corrosive atmospheres or other adverse conditions ; (ii) exposed to flammable surroundings or explosive atmosphere
* Electrical protection includes the provision of isolation, protective devices and earthing facilities as well as equipotential bonding of all the exposed conductive parts and extraneous conductive parts. * Electrical equipment should be so selected and erected that its temperature in normal operation and foreseeable temperature rise during a fault cannot cause a fire. * Suitable precautions should be taken where a reduction in voltage or loss and subsequent restoration of voltage, could cause danger . “Maintenance” In the design, construction and installation of an electrical installation, consideration must be given
to its subsequent maintenance. It should be noted that electrical equipment must not only be so constructed and protected as to be suitable for the conditions under which they are required to operate, but must also be installed to be capable of being maintained, inspected and tested with due regard to safety .
* An assessment should be made of any characteristics of equipment likely to have harmful effects upon other electrical equipment or other services, or impair the supply. Those characteristics include the following :- • overvoltages : • undervoltages : • fluctuating loads : • unbalanced loads : • voltage drop ( Vd ) : • power factor : • starting currents : • harmonic currents : • d.c. feedback : • necessity for additional connection to earth :

* Isolate and Lockout: The circuit / equipment under maintenance should be isolated as far as practicable. The relevant isolator should be locked out. A suitable warning notice should be placed close to the isolator . * De-energize The circuit/equipment to be worked on should be checked to ensure that it is dead . ←←←
* CIRCUIT ARRANGEMENT : • Basic Requirements of Circuits (1) Protection (2) Control (3) Identification (4) Electrical separation for essential circuits (5) Load distribution

* Basic Requirements of Circuits “ Protection “ Each circuit should be protected by an overcurrent protective device with its operating current value closely related to the current demand of the current using equipment connected or intended to be connected to it and to the current carrying capacity of the conductor connected. This arrangement will avoid danger in the event of a fault by ensuring prompt operation of the protective device at the appropriate current value which will otherwise cause damage to the cable or the current using equipment .

* Maintenance, Inspection and Testing :- (1) Identification ←← A Must ** (2) Maintainability (3) Inspection and testing

* Provision of Earthing :- The socket outlet should be so constructed that, when inserting the plug the earth connection is made before the current carrying pins of the plug become live. When withdrawing the plug, the current carrying parts should separate before the earth contact is broken.

 

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Calculation of current, voltage , résistance and power in simple series and parallel 12 and 24 volts circuits:

All these calculations are based on Ohm’s : In an electrical circuit, a voltage of one volt will pass a current of 1 ampere across a résistance of 1Ω . Ohm.
This law can be expressed mathematically:
The résistance of a circuit can be calculated by dividing the voltage of the circuit by the amount of current : R=V/I

The power of a circuit can be calculated by multiplying the current in a circuit by the voltage : W = I.V
As an apprentice, you need to commit these two formulae to memory. They are fundamental to all electrical calculations. Once you know these two formulae, you can re-arrange them to solve various different problems.

Some worked examples:
* In a plant vehicle fitted with a 12 volts electrical system, what is the résistance of the parking lamp circuit if 2 amperes of electricity flows ? : ( R = V/I = 12/2 = 6 Ohms. < )
* In a plant vehicle fitted with a 24 volt electrical system, what is the résistance of a headlamp circuit if an ammeter inserted in the circuit reads 10 amperes when the headlamp switch is closed ? ( R = V/I = 24/10 = 2.4 Ohms. )
* In a plant vehicle fitted with a 12 volt electrical system, how much current will flow in a warning beacon circuit, if the résistance of the beacon is 4 Ohms ? ( R = V/I; I = V/R = 12/4 = 3 amperes. )
* What is the voltage of a system if 4 amperes of flows in a circuit with a résistance of 3 Ohms ? ( R = V/I; V = R.I = 3*4 = 12 volts
* What is the power of a headlamp bulb that consumes 5 amperes when connected to a 12 volts supply ?
( W = I.V = 5 * 12 = 60 Watts . )
* How much current would a 60 Watt bulb consume when connected to a 24 volt source ? ( W = I.V; I =W/V = 60/24 = 2.5 amperes.

Great care must be exercised when using electrical equipment in high earth leakage areas such as cold rooms, washing up rooms, and in medical/biological laboratories where "wet" experiments are often in progress.

The reason for a fuse blowing, or a circuit breaker tripping, must always be investigated by a competent person and replacement fuses must always be of the correct rating.

Both Classes of equipment require an insulation test. Only Class 1 can be tested for earth bond resistance.

Only those who have both the knowledge and experience to make the right judgements and decisions and the necessary skill and ability to carry them into effect should undertake work subject to this Code. A little knowledge is often sufficient to make electrical equipment function but a much higher level of knowledge and experience is usually needed to ensure safety.

Manufacturers of any electrical equipment have a legal obligation to ensure that it is safe when properly used. Provided that the correct fuse has been fitted,

Equipment to be used out of doors should be fitted with a residual current device (RCD) to provide optimum protection. It should be noted, however, that the use of RCDs cannot be regarded as replacing primary safety features

 

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Mains input switches should be suitably placed on the machines, and the "On" and "Off" positions properly identified and accessible.
- All phases should be disconnected by the operation of the switch.
- An effective over-current protection device (e.g. a fuse) should be provided in each phase of the circuit and arranged so as to disconnect the electricity supply to the equipment in the event of overload or short circuit.

REPAIRS :
- During repairs, protective covers may have to be removed thereby exposing live parts.
- In these circumstances the hazard to be avoided is that of making a circuit from the high voltage conductor to another conductor or to earth via the human body, with risk of fatal injury.

- Electrical systems may involve a mains transformer, which reduces the voltages in the secondary to values less than 50 volts AC. In such a system the main risk will therefore be on the connections to the input to the primary.

** RCDs will not protect a person touching both live and neutral conductors. **

** The IEE Regulations state that all installations outside the equipotential zone, i.e. external/outdoor from the main installation should be protected by RCDs. The Regulations make it clear, however, that reliance on this form of protection is not acceptable as the sole or main means of protecting persons from electric shock. RCDs may only be used as a useful backup to primary safeguards such as insulation, enclosure, low voltage etc. **

* ( BS = British Standard )

Testing Process : 1 Visual Inspection : Class 1 Appliances : Yes : Class 2 Appliances : Yes 2 Earth : Class 1 Appliances : Yes : Class 2 Appliances : N/A 3 Insulation Test : Class 1 Appliances : Yes : Class 2 Appliances : Yes 4 Leakage Test : Class 1 Appliances : Yes : Class 2 Appliances : Yes 5 Load Test : Class 1 Appliances : Yes : Class 2 Appliances : Yes

* Single cables. Used throughout the industry, single cable comprise a central solid or stranded conductor which is given a single layer of insulation. The Insulation may be PVC, XLPE, LSF or some other specialist insulator depending on the application. Conductors are normally copper, although aluminium conductors used to be used.
Single cables require mechanical protection. They are commonly enclosed in conduit or trunking.

* Steel Wire Armoured cable (SWA). Used for installation in underground, external or exposed situations, SWA cabling is probably the most common cable for mains distribution although it is extensively used in smaller sizes as well. It generally comprises central copper or aluminium conductors which are insulated usually with XLPE. The conductors are protected against damage by steel wires and the whole cable is sheathed in a protective plastic outer sheath. Available in all sizes and current ratings that are likely to be encountered within a normal building. Specialist SWA cables are available such as Paper Insulated Lead Sheathed (PILC) but are rarely used in building services.

* Mineral Insulated Copper Clad Cable (MICC). (sometimes called MICS copper sheathed) This is a specialist cable that has copper inner conductors that are insulated with a mineral compound. The cable has an outer sheath of copper and can be further protected against the atmosphere by a outer plastic sheath. MICC is available in Heavy & Light gauges. Sizes above 35mm² are usually single core cable. MICC is expensive to purchase and specialist skills are needed to install it. However, it is long lived, is smaller that an equivalent SWA cable and importantly is fire proof. Hence it can be used to serve emergency services where the cable is required to remain in use during fire conditions

* Twin & Earth Cable (T&E) - Possibly the cheapest and easiest wiring to install twin & earth cable comprises a central conductor (usually solid) which has PVC insulation. Two insulated conductors are combined with a third uninsulated conductor (used as a CPC) and all three are enclosed in an outer PVC sheath. Variants are available with additional cores (Triple & Earth).
Twin & Earth cable is used in the vast majority of domestic installations, as well as in budget commercial applications, and other installations where funds are limited.
It lacks the protection possessed by other forms of cable unless enclosed in conduit. T&E wiring can become messy in all but the simplest of wiring applications. Also, it can be hard to rewire (as opposed to singles in conduit).
T&E cable is not highly suitable for most industrial applications, neither can it be used where there is a requirement for LSF cable.

* Flexible Cables. Used where a item of equipment is connected to an outlet or other termination. Flexible wiring is needed if it is likely that the equipment may move or vibrate in normal use. Many forms of flexible cable exist with many different forms of insulation. They all tend to have multistranded conductors and are all able to be flexed and bent without undue stress being placed on the conductor. ←←←

* Trunking. A form of containment that having a hollow box shaped section, and available in linear lengths. Trunking is available in both PVC and steel. PVC trunking can range in size from 15x15mm up to 150x150mm or even bigger and is quick and easy to install. Steel trunking affords better protection but is harder to install. Steel trunking comes in sizes from 50x50mm up to 300x300 and above.
Trunking is particularly suitable for use with single cables where many circuits can be contained in a single trunking (subject to compliance with BS7671 segregation regulations). Twin & Earth cables can also be protected by trunking.

* Conduit. Still by far the most common form of containment. Conduit comprises lengths of robust tube, available in set sizes 20mm, 25mm & 32mm. Conduit is available in both PVC and Steel form. PVC conduit is available in light & heavy duty grades and is relatively easy to install, requiring basic tools & adhesive to install. Steel conduit affords better protection than PVC but requires specialist tools and knowledge to install. It is available in Black Enamel (painted) finish or Galvanised finish (for exterior applications). Properly installed steel conduit can be used as a CPC.←←←

Conduit can be surface mounted or buried (flush) in walls. It is used extensively with single cables and Twin & Earth (for protection down walls ect.). Flexible conduit is not a direct variant of standard conduit, it is commonly formed from spiral arrangements of toughened PVC, steel or aluminium. The construction allows the conduit to be flexed and is normally used in short lengths to serve equipment and or items that may need to be moved.

* Cable Tray. Cable tray is a form of steel traywork, available in linear lengths which is used in industrial and commercial situations as a support for cables which are installed in free air (such as SWA and MICC cables) Cable tray is normally available in sizes between 50mm wide and 900mm wide, in a range of gauges light, medium & heavy duty. It is usually supplied galvanised, although special finishes such as power coating are sometimes used.
In recent years, plastic based alternatives have been developed.

* Cable Basket - Cable basket is a variant of cable tray. It comprises a basket like linear wire system which, although not a structurally strong as cable tray, is lighter and easier to install. It is commonly used for support of light cabling such as data & telephone wiring and has seen great increases in use with the advent of structured cabling systems.

* Floor trunking. A form of trunking that is specially adapted for installation within floor voids, or screeds. It commonly has two or more compartments enabling segregation and hence is used for 230V services as well as data and telecommunication systems. It is often fitted with custom floorboxes. Space restrictions can mean limited room in floor trunking and the number of cables able to be installed can present problems

 

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* Powertrack. A specialist form of trunking that contains busbars. This system is far smaller than the busbar distribution systems used in mains distribution. It is commonly rated at no more than 63A and is installed in floor or ceiling voids. Take off sockets are installed at regular intervals to allow the "Plugging in" of floorboxes, sockets and other equipment. Variants are available with clean earth facilities. This type containment is common in office premises as well as industrial situations ( Definitions p/27)

* Floor boxes - Commonly installed in conjunction with floor trunking systems or powertrack systems. Recessed floor boxes can be installed into a cavity floor or screeded floor. They comprise one or more compartments and accessory boxes which can be used to terminate many different services at one box. This enables users to plug in 230V power, data and telephones etc. at the same position, maybe under a desk. Common in open plan office developments.

- Modular systems - This phrase covers a wide range of various types of system, all of which are modular in their use and installation. Includes pre-wired conduits and trunking as well as modern systems which are wired on a "spider" system using pre-cut lengths of prewired flexible conduit or other flexible wiring. These systems have the great advantage of speed and ease of installation. They are popular in office type installations where large numbers of recessed fluorescent luminaires may be installed.

 

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Additional Letters are Optional ( such as ↔ IPXXB ↔ ) and they indicate the Degree of Protection of persons against access to hazardous parts :
* Additional Letters used in the IP code : A ↔ ( Protected against access with the back of the hand : Definition : the access probe. A sphere of 50mm diameter. Is required to have adequate clearance from hazardous parts , B ↔ ( Protected against access with a finger : Definition : the jointed test finger of 12mm diameter and 80mm length is required to have adequate clearance from hazardous parts : C ↔ ( Protected against access with tool : Definition : the access probe of 2.5mm diameter and 100mm length is required to have adequate clearance from hazardous parts : D ↔ ( Protected against access with a Wire : Definition : the access probe of 1mm diameter and 100mm length is required to have adequate clearance from
hazardous parts : BS-EN 60529 . Degrees of protection provided by enclosures ( IP )

 

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CSCS ← ← ←
Construction Signs are used on building and construction sites to show site safety policy requirements including PPE ( personal protection equipment ) rules.
Mandatory ↔ ( MUST OBEY ) ↔ Blue background with White Symbol ← ← ←
** The most popular construction safety signs are :-
"safety helmets, boots and vests to be worn at all times"

CSCS ←←←
A "prohibition sign" ↔ ( STOP/MUST NOT ) ↔ means a safety sign prohibiting behaviour likely to cause a risk to health or safety. These health & safety signs are required to be red. A prohibition sign shall show only what or who is forbidden. Prohibition safety signs generally use a black safety symbol in a red circle with a diagonal cross through.
** No Smoking symbol only - safety sign
** Description: prohibition > no smoking safety sign. no smoking symbol - cigarette & smoke in black with red prohibition circle & line through, white text on red background.
** No Smoking. it is against the law to smoke in these premises ( Red on White background ) ←←← -&-

CSCS A " ↔ WARNING SIGN ↔ " means a safety sign giving a warning of a risk to health or safety. Safety warning signs are required to be yellow or amber.
** construction site keep out - safety sign
** danger men at work
( Risk of Danger Hazard ahead ↔ Yellow background with ↔ Black Border ) ← ← ← -&-

 

[Stringbags]

Hi Amberleaf,

I have been teaching since 1992 and it would be difficult to find information better than that which you have provided, I am sure that the sparky community are very grateful, as so am I, but have you thought about writing all this down and producing a book, I for one would buy it.

Thanks from me and all of my apprentices.

Stringbags

 

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CSCS First Aid signs indicate the measures, means or personnel to give first aid in the event of an accident or injury.
** first aid cross symbol : Background Colour: Green .←←← -&- Text Colour: White
↔ ( SAFE WAY TO GO ) Safe Condition ↔ Green background with White Symbol ,

-&- are looking for ?
* Prohibition ! Red/White .
* Mandatory ! Must Obey . Blue background with White Symbol .
* Warning ! Risk of Danger Hazard ahead Yellow background with Black Border .
* Safe Way to Go : Safe-Condition . Green background with White Symbol .

Remember !! There are Four Type of Safety Sign in General Use -&- :This will get you buy a lot of things if you start with this principle

" prohibition sign " ↔ Round !!
“ Mandatory “ ↔ Round !!
“ WARNING SIGN “ ↔ Triangle !!
“ Safe Condition “ ↔ Square !!

Safety Signs & Their Meanings : CSCS :
Colour Red :
Meaning or purpose : Prohibition Sign ↔ Danger Alarm : Instructions and information ↔ ( Dangerous behaviour )
Meaning or purpose : Danger Alarm : Instructions and information ↔ ( Stop )
Meaning or purpose : Fire Fighting : Instructions and information ↔ ( Shutdown ↔ ( Emergency cut out devices ) ↔ ( Evacuate ) ↔ ( Identification and location )

Colour Yellow or Amber : Meaning or purpose : Warning Sign ↔ Be careful : Instructions and information ↔ ( take precautions ) ↔ ( Examine )

Colour Blue : Meaning or purpose : Mandatory Sign : Instructions and information ↔ ( Specific behaviour or action ) ↔ ( Wear personal protective equipment )

Colour Green : Meaning or purpose : Emergency Escape : Instructions and information ↔ ( Doors )
Meaning or purpose : ( First Aid Sign ) ↔ Instructions and information ↔ ( Exits )
Meaning or purpose : ( No danger ) ↔ Instructions and information ( Routes )
Instructions and information ↔ Equipment
Instructions and information ↔ Facilities
Instructions and information ↔ Return to normal

These ↔ Mandatory signs ↔ comply with BS5499 and The Safety Signs and Signals Regulations 1996. Mandatory signs - Instruct, advise and inform staff and visitors of an action that must be carried out to secure a safer working environment. Colour - blue symbol and background, white text. Symbol –

Eye protection safety sign.
Health and Safety at Work Act 1974, Anyone entering these premises must comply with regulations covered by the above act safety sign.

Fragile Roof Safety Signs manufactured to comply with The Safety Signs and Signals Regulations 1996
Access and Security Hazard Warning Sign. ( Danger fragile roof safety sign.) PS two different Signs ******
This safety sign gives warning to the danger of a fragile roof and ensures that caution is made. For safety, the sign also instructs the action to use crawling boards.
( be careful -&- may put up the ( Q :. danger of a fragile roof ) ↔ A : you may put up use crawling boards.

It may be handy to ask your Tutors for , The Heath & Safety Signs & Signal Posters , this will help your H&S

Barrier Tape !! what do you think ? Yellow & Black . Hint Warning

This British Standard outlines
• The arrow to be used with an escape route sign. →
• The arrow to be used with any other safe condition safety sign such as a first aid safety sign.
• The arrow to be used with a fire equipment safety sign.
• The arrow to be used with any other safe condition safety sign such as a first aid safety sign.
• The arrow to be used with a fire equipment safety sign.

How to assess the risks in your workplace
Follow the five steps :-
Step 1 ( Identify the hazards )
Step 2 ( Decide who might be harmed and how )
Step 3 ( Evaluate the risks and decide on precautions )
Step 4 ( Record your findings and implement them )
Step 5 ( Review your assessment and update if necessary )

 

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Carrying out a Risk Assessment

As well as the level of voltage, charge or current and the nature of the environment, there are a number of other factors that need to be considered when you are assessing the risk of injury arising from electrical testing work. A risk assessment should be carried out
before testing begins, to help you identify the precautions you need to take.

Some questions to ask when carrying out the risk assessment are :-
(a) Can the work be done with the equipment dead or energised at a safe voltage or current ?
(b) Is it absolutely necessary for someone to be working on or near to equipment that is live at dangerous voltages or current levels ?
(c) What is the maximum voltage on conductors that will be exposed during the work activity ?
(d) Are the testers competent? Are they adequately trained and knowledgeable to do the particular work and ensure that others are not put at risk ?
(e) If testers are not considered fully competent, are they adequately supervised ?
(f) What physical safeguards should be applied to the equipment under test to prevent injury, e.g. ? the use of temporary or permanent screens ?
(g) Is the test instrumentation of safe design ? Has it been properly maintained ?
(h) Is it necessary to set up a permanent test area separate from the rest of the workplace, where equipment can be taken for testing ? Is it necessary to set up a temporary test area around the equipment ?

'competent person'
In law, to be 'competent' means you have the necessary skills and experience, both theoretical and practical, to carry out inspections of the items placed before you.

Only you can decide if you are indeed competent to inspect a particular item,

What is an Accident ? PS . this may come up CSCS -&-
* An accident is an Unforeseen . unplanned and uncontrolled event . ←
* An accident is an Unfortunate . event resulting especially from carelessness or ignorance . ←

Accidents lead to injury to persons . damage to plane ( machinery/equipment ) or other losses .
Some accidents leads to serious injury , fatality or serious damage to property .

CSCS .
Reporting Accidents – Summary .
* All Accidents need to be reported and entered into the Accident Book ← -&- Q/As

* Serious Accidents and those where Employees are absent as a result of an Accident for more than three days must be reported to the Enforcing Authority ↔ ( Health & Safety Executive ) ***

Good practices:

CSCS : Ladders
Ladders are acceptable only for access or work of short duration.
They should be :-
Safe use of Ladders : * The ladder should be placed at a suitable angle, ideally at about ( 75° ← ) to the horizontal, i.e. about → ( 1m ) out of every → ( 4m ) in height. The user should face the ladder when climbing or descending. ↔ ( remember -&- on this one )
* erected at correct angle ( 4 up to 1 out) ↔ ( remember -&- on this one )
* secured ( preferably at top ) or footed
* positioned close to the work to avoid over-reaching
* sufficiently protected at the base of any ladder or access equipment to prevent pedestrians or vehicles bumping into them.

What is hand-arm vibration syndrome ? PS. This will come up -&-
Hand-arm vibration syndrome (HAVS) is a general term embracing various kinds of damage caused by exposing the hands to vibration. The more widely known of these is vibration white finger (VWF), which results from damage to blood vessels. Other forms of damage may be to the nerves and muscles of the fingers and hands, causing numbness and tingling, loss of feeling and reduced grip strength. People who have hand-arm vibration syndrome may also have an
increased risk of suffering from carpal tunnel syndrome (CTS). Pain and stiffness in the hands and joints of the
wrist, elbows and shoulders are other possible symptoms. HAVS and CTS are reportable diseases under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR ).

Q - What is hand-arm vibration syndrome ? A - the amount of vibration ; ****
Q- What are the symptoms ? A- the length of time for which the hands are exposed to the vibration ; ****

Provide the right equipment.
The Provision and Use of Work Equipment Regulations 1998 require employers to select and provide work equipment
that is suitable, with regard to the health and safety risks (including vibration) posed by the use of that equipment.

Everyone is required to ensure that the equipment used in their business conforms to the essential health and
safety requirements ( EHSRs) - in the case of vibration, the risks should be reduced to a minimum.
Under the Supply of Machinery (Safety) Regulations1992 (as amended 1994) there is a duty on manufacturers and suppliers of power tools to design, manufacture and supply tools for which risks from vibration have been reduced to the lowest level

Typical vibration exposure for powered handheld tools . meanings big jack hammers & other tools -&- may ask this !!!!!!!

Personal protection
“ Anti-Vibration Gloves “ are unlikely to reduce the dominant, low-frequency energy vibration from tools

Hand Arm Vibration :
WHAT SORT OF TOOLS AND EQUIPMENT CAN CAUSE VIBRATION INJURY ?

Industry : Type of Vibration ↔ Construction ↔ Common Source of Vibration ↔ Pneumatic tools, Jackhammers .
Concrete breakers ↔ Power hammers and chisels ↔ Pedestal grinders ↔ Hammer drills ↔ Hand-held grinders ↔ Hand-held sanders

* Safety Signs and Signals are one of the main means of communicating health and safety information.
* In view of their importance, it is critical that all Safety Signs and Signals can be easily understood.
* There are specific requirements for the shape, colour and pattern of Safety Signs.
* Any sign must contain a symbol or pictogram and be of a specified colour which clearly defines its meaning.
* Supplementary text may also be used to aid understanding, but text-only signs are not permitted.

 

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CSCS : Colour: Yellow or Amber : -&- may use the colour !! Amber ←←←

Banksmans ←← signals : they are used on Site !! CSCS .
Using banksmen to control reversing operations can put the Banksman in the potential danger area of a reversing vehicle. Every year banksmen suffer serious and fatal injuries whilst at work. If you do use banksmen, make sure they are trained to carry out their duties safely. There must be a safe system of work that ensures the Banksman and driver are using standard signals, so that they are easily understood, and that the driver knows to stop the vehicle immediately if the Banksman disappears from view.

Why record and report ?
Recording and reporting accidents and ill health at work is a legal requirement under The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR).
RIDDOR places a legal duty on:

• employers
• self-employed people
• people in control of premises.

These 'responsible persons' must record and report certain incidents, injuries, diseases and dangerous occurrences involving employees, self-employed workers and members of the public.

The information provided through recording and reporting enables the enforcing authorities (either Health and Safety Executive (HSE) or local authority Environmental Health), to identify where and how risks arise, and to investigate serious accidents.

With this information, the enforcing authorities are able to help and provide advice on how to reduce injury, and ill health in the workplace. Such surveillance data can also be used to put forward an evidence-based rationale for the introduction of new legislation and/or guidance.

Near Misses
Although not part of the legal duties mentioned above, it is also good practice to record non-reportable 'near-miss' incidents, workplace accidents and occurrences where no-one has actually been hurt or become ill, but where the consequences could have been serious for workers.

In this way, it is possible to learn from such incidents so that workers are protected from harm, using the old adage 'prevention is better than cure'.

It is also good practice to record 'near-miss' incidents.
( RIDDOR ) also requires responsible persons to report certain matters to their enforcing authority

H&S / CSCS . * ( Legionnaires Disease ) -&- is a potentially fatal form of pneumonia which can affect anybody, but which principally affects those who are susceptible because of age, illness, immunosuppression, smoking etc.

It is caused by the bacterium Legionella pneumophila and related bacteria that can be found naturally in environmental water sources such as rivers, lakes and reservoirs, usually in low numbers. As they are commonly found in environmental sources they may also be found in purpose built water systems such as cooling towers, evaporative condensers and whirlpool spas.

If conditions are favorable the bacterium may grow creating conditions in which the risk from legionnaires' disease is increased. It is therefore important to control the risks by introducing measures outlined in the Approved Code of Practice & guidance document

Working at Heights : this is what -&-s like here :

Ladders : Q/A
i) 3-Points of Contact .
ii) Correct Angle .
iii) Secured ?
iv) Safe and Suitable for Purpose .
v) Ladder Projecting above the Roof ?
vi) Always Check Ladder before Use .

Scaffolds :
i) Check Scaffold Tag – Why ? ←←
ii) Scaffold fitting with all Rail and Board Walks ?
iii) Are the Scaffold Planks in Good Structure ?
iv) Scaffold must be Inspected on a Weekly Basis .
v) Scaffold must be Inspected on a Weekly Basis .

Mobile Scaffolds : a Must -&-
i) Even Ground .
ii) Wheels Locked .
iii) Correct Access .
iv) Storage of Materials .
v) Ensure that the Scaffold can Handle the Load .

Pre-Checklist for Leaning Ladder : CSCS
i) Are the Sties in Good Condition ? ↔ if they are Bent or Split the Ladder Could Collapse .
ii) Stiles Checked ? ↔ if they are Bent or Damaged the Ladder could Buckle or Collapse .
iii) Feet Checked ? ↔ if they are Missing, Worn or Damaged the Ladder could Slip . ( *** Remember Rubber Feet on Ladders ) -&-
iv) Rungs Checked ? ↔ if they are Bent, Missing or Loose the Ladder could Become Unstable .

 

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Hoists :

* Has the Equipment been Installed by a Competent Person ?
* Are the Operators Trained and Competent ?
* is the Rated Capacity Clearly Marked ?
* Does the Hoist have a Current Report of Thorough Examination and a Recorded of Inspection ?
* is there a Suitable Base Enclosure to Prevent People from being Struck by any Moving Parts of the Hoist ?
* Are the Landing Gates Kept Shut Except when the Platform is at the Landing ?

**** This is True . a Builder was killed when he was Crushed between the Cage and the Fixed Structure of a Goods Hoist. The Hoist Moved Unexpectedly because the Safety Interlocks had been !!DEFEATED !! , The Hoist had been Poorly Maintained and did Not have a Current thorough Examination Report **** H&S . the Company was Fined Big Time . Poor Guy . Safety is a MUST on Site .Common Sense must Prevail !!!!!!!!!!!!!!!!
( You will Here the words “ Topman ↔ CSCS “ he is there to Cover your But . PS in theory when your down Holes / Pits / Hoists . Most Big Company’s Use them . ( Banksman and Topman are two different Persons on SITE ) ←← Ask your Tutor about them ,

Pre-Use Checklist for a Stepladder .
i) Locking Bars Checked ? if they are bent or the Fixings are Worn/Damaged the Ladder could Collapse .
ii) Feet Checked ? if they are Missing, Worn or Damaged the Ladder could Slip .
iii) Stepladder Platform Checked ? if it is Split or Buckled the Ladder could become Unstable or Collapse .
iv) Check the Steps or Treads ? if they are Contaminated-they could be Slippery .
v) Check the Steps ? if the fixing are Loose they could Collapse .
iv) Check the Stiles ? if they are Bent or Damaged-the Ladder could Buckle or Collapse .

The User ←←← ( Pat Test )
Users of the Equipment should be able to Check for Obvious Faults before Switching On and Using it. They must also know what to do if they find a Fault. Training may be required. H&S

What is a confined space? CSCS
It can be any space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions (e.g. Lack of Oxygen). Some confined spaces are fairly easy to identify, e.g. enclosures with limited
openings:
* storage tanks;
* silos;
* reaction vessels;
* enclosed drains;
* sewers.
Others may be less obvious, but can be equally dangerous, for example:
* open-topped chambers;
* vats;
* combustion chambers in furnaces etc;
* ductwork;
* unventilated or poorly ventilated rooms.

It is not possible to provide a comprehensive list of confined spaces. Some places may become confined spaces when work is carried out, or during their construction, fabrication or subsequent modification.

What is a confined space? CSCS
It can be any space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions (e.g. Lack of Oxygen). Some confined spaces are fairly easy to identify, e.g. enclosures with limited
openings:
* storage tanks;
* silos;
* reaction vessels;
* enclosed drains;
* sewers.
Others may be less obvious, but can be equally dangerous, for example:
* open-topped chambers;
* vats;
* combustion chambers in furnaces etc;
* ductwork;
* unventilated or poorly ventilated rooms.

It is not possible to provide a comprehensive list of confined spaces. Some places may become confined spaces when work is carried out, or during their construction, fabrication or subsequent modification.

What are the dangers from confined spaces ?
Dangers can arise in confined spaces because of :-
* A lack of oxygen.
This can occur :-
- where there is a reaction between some soils and the oxygen in the atmosphere;
- following the action of groundwater on chalk and limestone which can produce carbon dioxide and displace normal air;
- in ships’ holds, freight containers, lorries etc as a result of the cargo reacting with oxygen inside the space;
- inside steel tanks and vessels when rust forms. * Poisonous gas, fume or vapour.
These can:
- build-up in sewers and manholes and in pits connected to the system;
- enter tanks or vessels from connecting pipes;
- leak into trenches and pits in contaminated land, such as old refuse tips and old gas works.
* Liquids and solids which can suddenly fill the space, or release gases into it, when disturbed. Free flowing solids such as grain can also partially solidify or’ bridge’ in silos causing blockages which can collapse unexpectedly
* Fire and explosions (e.g. from flammable vapours, excess oxygen etc).
* Residues left in tanks, vessels etc, or remaining on internal surfaces which can give off gas, fume or vapour.
* Dust may be present in high concentrations, e.g. in flour silos.
* Hot conditions leading to a dangerous increase in body temperature Some of the above conditions may already be present in the confined space. However, some may arise through the work being carried out, or because of ineffective isolation of plant nearby, e.g. leakage from a pipe connected to the confined space. The enclosure and working space may increase other dangers arising through the work being carried out, for example:
* machinery being used may require special precautions, such as provision of dust extraction for a portable grinder, or special precautions against electric shock;
* gas, fume or vapour can arise from welding, or by use of volatile and often flammable solvents, adhesives etc;
* if access to the space is through a restricted entrance, such as a manhole, escape or rescue in an emergency will be more difficult ( ( see Emergency procedures ). ↔ that’s what a Topman if For !!!!!!!!

What the law says
You must carry out a suitable and sufficient assessment of the risks for all work activities for the purpose of deciding what measures are necessary for safety (The Management of Health and Safety at Work Regulations 1999, regulation 3). For work in confined spaces this means identifying the hazards present, assessing the risks and determining what precautions to take. In most cases the assessment
will include consideration of:
the task :-
* the working environment;
* working materials and tools;
* the suitability of those carrying out the task;
* arrangements for emergency rescue.

↔↔ Risk Assessment at All Times ↔↔ Chaps .

If your assessment identifies risks of serious injury from work in confined spaces, such as the dangers highlighted above, the Confined Spaces Regulations 1997 apply. These regulations contain the following key duties:
* avoid entry to confined spaces, eg by doing the work from outside;
* if entry to a confined space is unavoidable, follow a safe system of work; and
* put in place adequate emergency arrangements before the work starts.

Avoid entering confined spaces
You need to check if the work can be done another way so that entry or work in confined spaces is avoided. Better work-planning or a different approach can reduce the need for confined space working. Ask yourself if the intended work is really necessary, or could you :-
“” modify “” the confined space itself so that entry is not necessary;
* have the work done from outside, for example:
* blockages can be cleared in silos by use of remotely operated rotating flail devices, vibrators or air purgers;
* inspection, sampling and cleaning operations can often be done from outside the space using appropriate equipment and tools;
* remote cameras can be used for internal inspection of vessels.

Safe systems of work
If you cannot avoid entry into a confined space make sure you have a safe system for working inside the space.
Use the results of your risk assessment to help identify the necessary precautions to reduce the risk of injury. These will depend on the nature of the confined space, the associated risk and the work involved.

Make sure that the safe system of work, including the precautions identified, is developed and put into practice. Everyone involved will need to be properly trained and instructed to make sure they know what to do and how to do it safely.
The following checklist is not intended to be exhaustive but includes many of the essential elements to help prepare a safe system of work.

Are persons suitable for the work ?
Do they have sufficient experience of the type of work to be carried out, and what training have they received? Where risk assessment highlights exceptional constraints as a result of the physical layout, are individuals of suitable build ?
The competent person may need to consider other factors, e.g. concerning claustrophobia or fitness to wear breathing apparatus, and medical advice on an individual’s suitability may be needed.

Isolation
Mechanical and electrical isolation of equipment is essential if it could otherwise operate, or be operated, inadvertently. If gas, fume or vapour could enter the confined space, physical isolation of pipework etc needs to be made. In all cases a
check should be made to ensure isolation is effective.

Check the size of the entrance
Is it big enough to allow workers wearing all the necessary equipment to climb in and out easily, and provide ready access and egress in an emergency? For example, the size of the opening may mean choosing air-line breathing apparatus
in place of self-contained equipment which is more bulky and therefore likely to restrict ready passage.

 

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Provision of ventilation
You may be able to increase the number of openings and therefore improve ventilation. Mechanical ventilation may be necessary to ensure an adequate supply of fresh air. This is essential where portable gas cylinders and diesel-fuelled
equipment are used inside the space because of the dangers from build-up of engine exhaust. Warning: carbon monoxide in the exhaust from petrol-fuelled engines is so dangerous that use of such equipment in confined spaces should never be allowed.

Testing the air
This may be necessary to check that it is free from both toxic and flammable vapours and that it is fit to breathe. Testing should be carried out by a competent person using a suitable gas detector which is correctly calibrated. Where the risk
assessment indicates that conditions may change, or as a further precaution, continuous monitoring of the air may be necessary.

Provision of special tools and lighting -&- loves this One ? why
Non-sparking tools and specially protected lighting are essential where flammable or potentially explosive atmospheres are likely. In certain confined spaces (e.g. inside metal tanks) suitable precautions to prevent electric shock include use of extra low voltage equipment (typically less than 25 V) and, where necessary, residual current devices.

Provision of rescue harnesses
Lifelines attached to harnesses should run back to a point outside the confined space.

Communications
An adequate communications system is needed to enable communication between people inside and outside the confined space and to summon help in an emergency.

Check how the alarm is raised
Is it necessary to station someone outside to keep watch and to communicate with anyone inside, raise the alarm quickly in an emergency, and take charge of the rescue procedures?

Is a ‘permit-to-work’ necessary ? CSCS -&-
A permit-to-work ensures a formal check is undertaken to ensure all the elements of a safe system of work are in place before people are allowed to enter or work in the confined space. It is also a means of communication between site
management, supervisors, and those carrying out the hazardous work. Essential features of a permit-to-work are:
* clear identification of who may authorise particular jobs (and any limits to their authority) and who is responsible for specifying the necessary precautions(eg isolation, air testing, emergency arrangements etc);
* provision for ensuring that contractors engaged to carry out work are included;
* training and instruction in the issue of permits;
* monitoring and auditing to ensure that the system works as intended.

Shut down
It may be necessary to shut down adjacent plant before attempting emergency rescue. ↔ ( A Must )
First-aid procedures
Trained first aiders need to be available to make proper use of any necessary first-aid equipment provided.

Local emergency services
How are the local emergency services (eg, fire brigade) made aware of an incident ?
What information about the particular dangers in the confined space is given to them on their arrival ?

Relevant law
* The Confined Spaces Regulations 1997;
* The Management of Health and Safety at Work Regulations 1999;
* The Control of Substances Hazardous to Health Regulations 2002 (as amended);
* The Personal Protective Equipment at Work Regulations 1992 (as amended);
* The Provision and Use of Work Equipment Regulations 1998;
* Electricity at Work Regulations 1989;
* Workplace (Health, Safety and Welfare) Regulations 1992.

Some of the above law is relevant because of the nature of the work to be carried out inside a confined space, e.g. where there are risks from machinery, electricity or from hazardous substances.

All I ask is you tell your Mates about This Site . Please ( Amberleaf )
PS : Thank You Dan and The Chaps for There Air Space ←←←←←←←←

Wearing Ear Protection : ↔ ( Remember Mandatory : Must Obey / Blue/White Symbol .
You should Wear Ear Protection when the sound Level is between the 85db and 90db action Levels . you must Wear it above 90db .
Without Protection there is a Risk of Damage to your Hearing . Remember that, over time, this Damage can result in Permanent Hearing Loss. Ear Protection cannot repair Damage that has already been caused .
Noise Level 20db / Activity , Quiet Whisper .
Noise Level 60db / Activity , Car at 50km/hour
Noise Level 80db / Activity , Home hi-fi .
Noise Level 83db / Activity , Bricklayer .
Noise Level 90db / Activity , Passing tube train .
Noise Level 92db / Activity , Carpenter .
Noise Level 101db / Activity , Portable power tools .
Noise Level 102db / Activity , Bench saws .
Noise Level 110db / Activity , Pneumatic drill, Nightclub .
Noise Level 120db / Activity , Rock Concert .
Noise Level 140db / Activity , Cartridge Tools ( they don’t give you Warning when they fire the bloody thing )

Noise at Work Regulations 1989 :
Noise Levels are Measured with Sound Level Meters. They have up to four Scales. ( A to D ) which give readings in Decibels ( db )
The most Common Scale for Construction Work and for Legal Purposes is the ( A ) Scale .
The Regulations Identify time Limits for Exposure to various Sound Levels and set Out three action Levels :-
First Level 85db ( A ) Scale :-
Employee is Provided, at their Request, with Suitable and Efficient Personal Ear Protectors .

Second Level 90db ( A ) Scale :-
Employee is Provided with Suitable Personal Ear Protectors, which must be Worn .

Peak Level 140db ( A ) Scale :-
Employee must Wear the Personal Protective Equipment ( PPE ) Provided as Noise at this Level will Cause Permanent Damage to Hearing .

Noise Assessments should be Carried Out by a Competent Person .

Change to the Noise at Work Regulations :
The Current Regulations were Adopted in November 2002 : from December 2005 the Limits of the First and Second action Levels will be Reduced by 5db .

Pump Down the Volume : Noise Safety .
Noise is the Sound made by Pressure Changes in the Air and picked up by your Ear.
Loud Noise can Annoy People. More Importantly, it can Damage you Hearing. But very Soft Noise can be Difficult to hear .

People who are Exposed to High Noise Levels, even for a Sort time, may Experience Temporary Hearing Loss .
If they are Exposed to Noise for a long time they can Suffer Serious, Permanent Hearing Loss. Sufferers don’t often realise that their Hearing is Damaged until other people ask : “ Can’t you Hear me ? Are you Deaf ?

The Damage happens when Pressure Changes in the Air Affect the Inner Ear. This is the part of the Ear that allows you to Hear.
You will find that Loud Noise over a Short Period of time can Cause Temporary Hearing Loss and a “ Buzzing “ in your Ears .

At Work. Noise can Stop you Concentrating. It distracts you and may make you Unsafe. There is Legislation in Place to help Protect your Hearing throughout your Lifetime .

Noise is Measured in Decibels ( db )
As a Guide. A Useful “ Rule of Thumb “ is :-

* if you have to raise your voice to speak to someone 2 meters away. Noise Levels are about ( 85db )
* f you have to Shout to Speak to Someone who is 1 meters away. Noise Levels are about ( 90db )

Identifying “ Ear Protection Zones “ and putting up Signs where Noise is at or Above ( 90db ) can Control the Effects of Noise .

Working with Power: Electrical Safety

It’s therefore Very Important that you Make Sure any Electrical Equipment ( Including Powered Hand Tools ) are Safe to Work with .
To do this you must Follow these Safety Procedures .

* Do Not Plug in Before Checking :
When you first come across a piece of Electrical Equipment or Powered Hand Tool. You Won’t know if it is Safe to Plug in and Work with
The Rule is “ Do Not Plug in Until you have Checked the Tool “ if you Plug the Powered Tool in and there is a Fault with it, you could be Seriously Injured or Killed !!

* Check Body of Power Tool :
Check that the Body of the Tool is Clean and free from Grease or Excessive Dirt, This Dirt could make the Tool more Difficult to Hold and Control. It could also Hide other Defects, Check for Cracks in the Body, Check for Loose Fittings and Missing Bits of the Tool.
Check as well to see if there is an Up-to-Date ( Pat Label on the Tool ) ↔ -&- Pat is the “ Pat is the “ Portable Appliance Test “
This will show it has Passed an Electrical Safety Test on a Particular Date . the Test must be Carried Out by a Competent Person .

* Check Cable on Power Tool :
The Cable could be Considered the “ Weaker “ Part of the Power Tool. It often lies on the Ground in Dirt and Water and can easily be Damaged by Treading or Driving Over it . Check the Cable for Cuts, Abrasions, Burns, Bare Wires and Frayed Ends ,

Working with Power: Electrical Safety .

* Check Plug of Power Tool :-
The Plug needs to be Checked to make sure it is Not Dirty, Wet or Covered in Grease. Check the Pins are in Place and Not Loose or Misshapen. Also Check the Casing of the Socket to make sure the Spring-Loaded Cover Operates Correctly and that it is Not Cracked .

* Check Voltage of Power Tool :
If the Plug and Cable are Colored Yellow the Power Tool will Operate at 110Volts . there may also be Labels on the Power Tool showing
110Volts . To Work on Building Sites, all Power Tools should be at this Reduced Voltage or , better still, Battery Operated .

* Plug in Power Tool :-
Once you have made all the Checks Correctly. You can plug in Power Tool and start Work. If you are Not Sure about the Checks you have just made, do Not-Plug in the Tool and Do Not Start-Work. Go and ask Advice from your Supervisor .

There is No-Set Procedure for Checking Power Tools before Use, but it is Good Practice to Decide your own Routine .