***Useful Information For The Working Sparky***

[amberleaf]

“ Rcd's “

Fire detection circuits must be supplied independently of other circuits and not protected by an Rcd protecting multiple circuits. 560.7.1 All circuits in a bath shower room must be protected by a 30mA RCD. P166, 701.411.3.3
Where applicable an RCD notice must be fixed on or next to the CCU 514.12.2 An RCD should not be used as a main switch 314.2 If the maximum Zs values for a circuit in a TN systems cannot be met, the circuit may be protected by a 30mA RCD. 531.3.1
If the maximum Zs values for a TN systems cannot be met, the installation may be protected by an 100mA RCD and treated as a TT systems . 531.3.1 : 411.5.1 : 411.5.2 : 411.5.3
Unless specifically labelled or suitably identified, all 13A socket outlets must be protected by a 30mA Rcd. 411.3.3
In a TN systems , the part of a lighting circuit in a bath or shower room is required to be 30mA RCD protected. 411.3.3 , 701.411.3.3

Where a cable is buried in a wall or partition at a depth of less than 50mm on either side it must be sufficiently mechanically protected against penetration OR RCD protected AND installed either horizontally within 150mm of the top of the wall or vertically within 150mm of the angle formed where two walls meet or run horizontally or vertically to an accessory, luminaire or CCU 522.6.6 , 522.6.7 . This applies to a cable in a partition constructed using metallic parts other than fixings irrespective of the cable depth. 522.6.8

Surface run cables do not require RCD protection. OSG p22

A single RCD protecting a TT systems must be installed at the origin of the installation unless the part of the system between the origin and the RCD fulfils the requirements for protection by Class 11 equipment or equivalent insulation 531.4.1

All Electrical equipment must be accessible for operation , inspection & testing maintenance and repair. 132.12

Rcd Test Procedure

Many RCD test meters have a facility where tests can be carried out during the positive or negative half of the supply cycle. For tests 1 & 2 the RCD operating time to be recorded is the longer of the two measured during the half cycle tests.

DO NOT press the test button on the RCD before testing as this can temporarily reset a faulty RCD

Test 1
Adjust the current setting on the test meter to 100% of the rated trip current of the RCD and perform a test. A general purpose BS4293 RCD should operate within 200mS . A general purpose BS-61008 RCD or RCBO to BS-61009 should operate within 300ms

Test 2
An RCD provided for Basic Protection should have a rated TRIP current not exceeding 30mA If the RCD is rated at 30mA , adjust the current setting on the test meter to 150ma ( x5 ) and perform a test. The RCD must operate in a time not exceeding 40mS.
Test 3
Adjust the current setting on the test meter to 50% of the RCD trip current and perform a test. The RCD should not operate within 2 seconds
The Test Button : Finally operate the RCD by pressing its test button

 

[Spudnik]

Re: useful information

Another useful post there Mr Leaf.

Ill stick this one too, and i would respectfully ask members to refrain from posting here so that we can keep the thread clear.

Thanks.

 

[amberleaf]

“ Certification & Reporting “
Before an Installation or an additions & alterations’ to an installation is energised, inspection and testing must be carried out to ensure the requirements of BS-7671 have been met and an appropriate certificate must then be issued. ( 134.2.1, 610.6 631.1 )
Steps must be taken to avoid damage to property and equipment and to avoid danger and injury to persons during inspection and testing. 610.1
Any defects found in the existing installation must be recorded on the Electrical Installation Certificate or Minor Electrical Installation Works Certificate. 633.2
A durable copy of the schedule from the electrical installation certificate must be fixed next to or placed inside the consumer unit. In addition to circuit details the schedule must a contain information about the protective measures used in the installation i.e. automatic disconnection of supply, electrical separation SELV , RCD, 132.13 514.9

The Periodic Inspection Report must only be used to report on the condition of an existing installation. p339

BS-7671 does not give specific details on the frequency of periodic inspection & testing of a domestic installation. 622.1. Guidance Note 3 suggests every 10 years or every change of occupancy.

The Minor Works Certificate must only be used where additions & alterations’ to an existing installation do not include a new circuit. p336 , 631.3

The Electrical Installation Certificate must only be used to certify a new installation, new circuits in an existing installation or new work that includes additions & alterations’ to an existing installation. An Electrical Installation Certificate must not be used to report on the condition of an existing installation. p334 , 631.1

NICEIC Domestic Electrical Installation Certificates require that an additional 'Certificate of Design, Installation & Commissioning Of A Fire Detection & Alarm System Of Grade B, C, D, E or F In A Dwelling' must be provided for any fire detection systems including smoke alarms that are part of the installation.

Electrical separation is a protective measure for circuits up to 500v ac. 413.3.2 An example of electrical separation in a domestic installation is a shaver socket.
Protection by electrical separation in a bathroom or shower must only be used for :
a. one single socket outlet, or

b. circuits supplying one item of current using equipment 701.413

All circuits in a bathroom or shower room must be protected by a 30ma RCD p166, 701.411.3.3

Only one item of current using equipment may be supplied using electrical separation. 413.1.2, 701.413

All items of current using equipment must be provided with a functional switching device. 537.5.1.3

Electrical floor heating systems must not be supplied using electrical separation. 701.753

All electrical equipment must be accessible for operation, inspection & testing, maintenance and repair. 132.12

For more information on electrical separation see 413.1, 418.3, 701.1, 612.4.3

“ Incoming Supply “

A main switch must be provided to cut off the voltage to an installation. 132.15.1 *

A double pole main switch or linked circuit breaker must be installed as close as possible to the incoming supply at the origin of the installation. 537.1.4 *

If an installation in the United Kingdom does not comply with Chapter 13 of BS-7671 the electricity supplier does not have to provide a supply to the property. p241 *

A TN-S supply has separate neutral and protective conductors. All the exposed conductive parts of the installation must be connected to the protective conductor at the main earthing terminal. p30, p33 *

A TN-C-S supply has a combined neutral and protective conductor. All the exposed conductive parts of the installation must be connected to the combined neutral and protective conductor at the main earthing terminal. This type of system is also known as PME (protective multiple earthing). p30, p33 *

PME submains are not permitted. 543.4.9 *
230v final circuits in a TN system not rated greater than 32A must disconnect within 0.4 seconds under fault conditions. 411.3.2.2 *
Under fault conditions in a TN system, circuits over 32A including distribution circuits must disconnect within 5 seconds. 411.3.2.3 *
If the maximum Zs value for a circuit in a TN system cannot be met, the circuit may be protected by a 30ma RCD. 531.3.1 *
If the maximum Ze value for a TN system cannot be met, the installation may be protected by a 100ma RCD and treated as a TT system. 531.3.1 , 411.5.1 , 411.5.2 , 411.5.3 *
A TT supply has the exposed conductive parts of the installation connected to an earth electrode which is separate from the earth of the supply. p30 , p34 *
A single RCD protecting a TT system must be installed at the origin of the installation unless the part of the system between the origin and the RCD fulfils the requirements for protection by Class II equipment or equivalent insulation . 531.4.1 *
230v final circuits in a TT system not rated greater than 32A must disconnect within 0.2 seconds under fault conditions. If disconnection is made by a fuse or mcb and all extraneous conductive parts are connected to the main equipotential bonding then a disconnection time of 0.4 seconds is permitted. 411.3.2.2
Under fault conditions in a TT system, circuits over 32A including distribution circuits must disconnect within 1 second. 411.3.2.4 *
For more information about TT systems see 411.5.2, 612.8.1 * It is assumed that where an installation is supplied in accordance with the Electricity Safety, Quality and Continuity Regulations 2002 the connection between the supply neutral and earth is permanent. 114.1 *
The incoming supply to a domestic property is 230v with a permitted tolerance of +10% / - 6% ie 216.2v - 253.0v. p 242 *
Meter tails are part of the consumers installation and are to be provided by the installer. Meter tails must be sheathed and insulated or if insulated only must be enclosed in trunking or conduit. Meter tails must be 25mm. Where the meter tails are protected against fault current by the main fuse the installation method, maximum length and minimum cross sectional area must meet the distributors requirements. OSG p17
A distribution circuit is the circuit that connects the incoming supply to the ccu i.e. meter tails. When a distribution circuit supplies an installation remote from the incoming supply it is sometimes referred to as a sub main. p23

Extractor Fans Extractor fans must be provided with an easily accessible means of switching off the supply 132.15.2 Electrical Equipment that may cause injury during mechanical maintenance i.e. fans, must be provided with a means to switch off the supply. 537.3.1.1 All items of current using Equipment must be provided with a functional switching device. 537.5.1.3 All Electrical Equipment must be accessible for operation, inspection & testing , maintenance and repair. 132.12
“ Immersion Heaters “
An immersion heater must not be supplied by a ring final circuit. p362, 433.1.5
An immersion heater must be connected to the supply by a double pole linked switch only. The use of a plug top and socket outlet is not permitted. 554.3.3
An immersion heater must be provided with a thermal cut-out to prevent the water from boiling if the thermostat fails. 554.2.1
All final circuits must be wired separately from all other final circuits. 314.4
All Electrical Equipment must be accessible for operation, inspection & testing, maintenance and repair. 132.12

 

[amberleaf]

“ Lighting Circuits “
All electrical equipment must be accessible for operation, inspection & testing, maintenance and repair. 132.12 Where an installation has only one lighting circuit, the circuit may need to be divided into two circuits to minimize the danger that may arise in the event of a fault. 314.1 (iii) Light fittings must be installed so that any radiated heat does not cause any damage. 559.5.1 The fixing supporting a light fitting must be able to support a weight of at least 5kg. 559.6.1.5 Domestic lighting circuits should not be rated at more than 16A. 559.6.1.6 Edison screw lampholders (excluding types E14, E27 ) should have the outer contact connected to the neutral conductors’ . 559.6.1.8 Lighting circuits must be controlled by the appropriate number of switches. 559.6.1.9 p146 Through wiring is only permitted in a light fitting where the light fitting is designed for such wiring. 559.6.2.1 p146 Through wiring in a light fitting must be suitable for the temperature generated inside the fitting. 559.6.2.2 The lamp inside an outdoor light fitting mounted less than 2.8m above the ground must only be accessible after removing an enclosure or barrier with the use of a tool. 559.10.3.1 Electrical equipment outdoors must be rated at least IP33. 559.10.5.2 Switch lines must be marked brown at their terminations. 514.3.1, p91

Lighting Circuits In A Bath Or Shower Room
In a TN Systems the part of a lighting circuit in a bath or shower room is required to be 30ma RCD protected. P47 , 411.3.3 , p166 , 701.411.3.3 Electrical equipment installed within zone 0 must be at least IPX7. 701.512.2 Only switches that are built into fixed Electrical equipment and the insulated pull cords of pull cord switches are permitted in zone 0. No other switches or accessories are allowed. 701.512.3 Only SELV equipment not exceeding 12v ac or 30v dc is permitted in zone 0. The SELV equipment must be fixed and permanently connected with the transformer and isolator outside zones 0, 1 & 2. 701.55 Electrical equipment installed within zone 1 must be at least IPX4 . 701.512.2 Only switches that are built into fixed Electrical equipment , the insulated pull cords of pull cord switches and switches of SELV circuits not exceeding 12v ac or 30v dc are permitted in zone 1. The SELV transformer and isolator must be outside zones 0, 1 & 2. No other switches or accessories are allowed. 701.512.3 p167 Light fittings are permitted in zone 1 and must be fixed and permanently connected. 701.55 Lighting fittings and switches installed within zone 2 must be at least IPX4. 701.512.2 Only switches that are built into fixed Electrical equipment , the insulated pull cords of pull cord switches, BS EN 61558-2-5 shaver units and socket outlets’ and switches of SELV circuits not exceeding 12v ac or 30v dc are permitted in zone 2. The SELV transformer and isolator must be outside zones 0, 1 & 2. No other switches or accessories are allowed. 701.512.3 For information on extra low voltage lighting see 559.11 For information on suspended lighting systems see 559.11.6 All final circuits must be wired separately from all other final circuits. 314.4

 

[amberleaf]

“ Fire Detection “ part P : for testers
All electrical equipment must be accessible for operation, inspection & testing , maintenance and repair. 132.12 *
NICEIC Domestic electrical Installation Certificates’ require that an additional 'Certificate of Design, Installation & Commissioning Of A Fire Detection & Alarm System Of Grade B, C, D, E or F In A Dwelling' must be provided for any fire detection systems including smoke alarms that are part of the installation. * Fire detection circuits must be supplied independently of other circuits and not protected by an RCD protecting multiple circuits. 560.7.1 * All literature supplied with fire detection equipment must be made available to the occupant of the dwelling. 560.7.12 * Fire detection cables, not including metal screened fire resistant cables, must be adequately segregated from cables supplying other circuits. 560.7.7 * BS-7671 does not provide detailed information for fire detection systems and is supplemented by BS 5839. p12 * The Building Regulations 1991 require all new and refurbished dwellings to be fitted with mains operated smoke alarms. The requirements for single family homes of not more than two storeys are that self-contained smoke alarms should be installed as follows : ** (i) at least one smoke alarm on each floor * (ii) within 7m of kitchens and living rooms and other areas where fires may start * (iii) within 3m of all bedroom doors * The smoke alarm must be installed in accordance with the manufacturers’ instructions, generally on ceilings and at least 300mm from any wall or ceiling light fitting ** The smoke alarms have to be interconnected, have a battery backup, and be permanently supplied from a separate way in the ccu , or supplied from a local lighting circuit that is regularly used. Please note this requirement conflicts with 560.7.1 Except for TT systems, the circuit supplying a smoke alarm should not be protected by an RCD. For TT systems the smoke alarm must be supplied from the fixed equipment section of the ccu, not through a 30mA RCD. ** The cables supplying each self-contained smoke alarm and supplying the interconnections between smoke alarms do not have to be fire retardant and need not be segregated. ** The Grade System - is the system of engineering, not the level of protection. * Grade F - one or more battery powered smoke and heat alarms. * Grade E - a system of interlinked mains powered smoke and heat alarms with NO battery back up. * Grade D - a system of interlinked mains powered smoke and heat alarms with battery back up. * Grade C - a system consisting of smoke detectors and sounders (which may be smoke alarms) connected to a common power supply, comprising of mains power and a stand by supply with central control equipment * Grade B - fire detection and alarm system comprising of fire detectors (other than smoke alarms), fire alarm sounders and control and indicating equipment to either BS EN 54-2 and power supply to BS EN 54-4, or to Annex C of BS 5839 pt6. * Grade A - fire detection incorporating control and indicating equipment to either BS EN 54-2 and power supply to BS EN 54-4 installed to BS 5839 : Pt 1 with some minor exceptions’. * Grade D is required for new, owner occupied buildings of up to three storeys, two storey rented properties, and existing owner occupied buildings of up to two storeys. Very large storeys may require a Grade B alarm system. * Levels Of Protection * LD1 - a system installed throughout the dwelling, incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling and in all rooms and areas in which fires may start, other than toilets, bath and shower room ** LD2 - a system incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling, and in all rooms or areas that present a high risk of fire. ** LD3 - a system incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling.

 

[amberleaf]

“ FELV, PELV & SELV “

All items of current using equipment must be provided with a functional switching device. 537.5.1.3 *

FELV (functional extra low voltage) is an extra low voltage system (up to 50v ac, 120v dc) without all of the protective measures applied to PELV or SELV. p24 *

For more detailed information on FELV see 411.7, 612.4.4

PELV ( protective extra low voltage ) is an extra low voltage system ( up to 50v ac, 120v dc ) with a connection to earth. p27 *

For more detailed information on PELV see 414.1, 612.4.2 *

SELV ( separated extra low voltage ) is an extra low voltage system ( up to 50v ac, 120v dc ) with no connection to earth. p29 *

For more detailed information on SELV see 414.1, 612.4.1 *

Extra Low Voltage circuits should not be run in the same wiring system as 230v circuits unless all ELV cables and conductors are insulated for 230v or separated by an earthed metal screen. 528.1 *

All electrical equipment must be accessible for operation, inspection & testing , maintenance and repair. 132.12 *

“ Underfloor Heating “ All items of current using equipment must be provided with a functional switching device. 537.5.1.3 * Electric floor heating must not be protected by electrical separation. 701.753 * All circuits in a bath or shower room must be protected by a 30ma RCD. 701.411.3.3 * Electric floor heating in a bath or shower room must have a metal enclosure or sheath or a fine mesh metallic grid connected to the cpc of the supply circuit SELV supplies excluded ). 701.753 p/168 * All electrical equipment must be accessible for operation, inspection & testing, maintenance and repair. 132.12 * For more information on electric floor heating see 554.4, 753.1 *

“ Reference Methods “
PVC cables surface clipped - C
Armoured cables surface clipped - C
MICC cables surface clipped - C
PVC cables installed directly in an insulated wall - A
PVC cables installed in a building void - B
PVC cables in metal / plastic conduit or trunking surface mounted on a wall - B
PVC cables in metal / plastic conduit installed inside an insulated wall - A
PVC cables in metal / plastic conduit installed inside a building void - B
For more detailed information see Table 4A2 p261

 

[Mac]

Re: useful information

Another useful post there Mr Leaf.

Ill stick this one too, and i would respectfully ask members to refrain from posting here so that we can keep the thread clear.

Thanks.[/quote
Hi Jason,all these threads that amberleaf is posting,is there anyway that they can be compressed by the admin into a sort of folder or something.Just a ?.He is doing a great job

 

[amberleaf]

“ Basic & Fault Protection “
Basic Protection is protection against electric shock under normal operating conditions. , p20
Fault Protection is protection against electric shock with regard to a failure of basic insulation, p24
Exposed conductive parts of less than 50mm2 are exempt from fault protection. 410.3.9 *

Cables
Fire detection cables, not including metal screened fire resistant cables, must be adequately segregated from cables supplying other circuits. 560.7.7 * Cables must be suitably supported i.e. clipped or installed in conduit or trunking. 522.8.4 * Cables should be installed so as to avoid any possible damage caused by mechanical stress. 522.6.1 * Non sheathed cables (excluding protective conductors) must be installed in conduit, trunking or ducting. 521.10.1 * Cables must be not installed where they can be affected by heat from an external source. 522.2.1, 528.3.1 * Cables passing through a joist must be 50mm from the top or bottom of the joist or be sufficiently protected against damage. 522.6.5 * Where a cable is buried in a wall or partition at a depth of less than 50mm on either side it must be sufficiently mechanically protected against penetration OR Rcd protected AND installed either horizontally within150mm of the top of the wall or vertically within 150mm of the angle formed where two walls meet or run horizontally or vertically to an accessory, luminaire or ccu. 522.6.6 , 522.6.7. This applies to a cable in a partition constructed using metallic parts other than fixings irrespective of the cable depth. 522.6.8 * Surface run cables do not require RCD protection. OSG p22 * Cables buried underground must be armoured or have a metal sheath or be installed in a metal conduit or duct. Buried cables must be identified by cable covers or marking tape and buried at sufficient depth to avoid damage. 522.8.10 * Cables should not be run through a load bearing part of a building if the integrity of the load bearing part is compromised by the passage of the cable. 522.8.14 * Wherever possible cables should not be covered by thermal insulation. A cable covered by thermal insulation for more than 0.5m must have its current carrying capacity derated by a factor of 0.5. For more information see 523.7 *Where the sheath has been removed from a cable its cores must be enclosed within an accessory or enclosure of the appropriate standard. 526.9 * When a cable, conduit or trunking passes through a wall or floor it is necessary to seal the hole around the cable, conduit or trunking to the standard of the original wall or floor including any fire resistant/retardant properties. 527.2.1 * Switch lines must be marked brown at their terminations 514.3.1 , p343 * Telecommunication cables and power cables must not be run together. 528.2 * Main bonding conductors should not be supported by the service pipes they are connected to. 543.3.1 * Single core armoured cables must not be used in an a.c. circuit. 521.5.2 * Meter tails are part of the consumers installation and are to be provided by the installer. Meter tails must be sheathed and insulated or if insulated only must be enclosed in trunking or conduit. Meter tails must be 25mm. Where the meter tails are protected against fault current by the main fuse the installation method, maximum length and minimum cross sectional area must meet the distributors requirements. OSG p17 * Electricity cables must be spaced at least 25mm away from gas pipes up to 35mm and 50mm away from gas pipes over 35mm unless the pipes are PVC wrapped or a pane of insulating material is separating them. OSG p18 * PVC cables must be kept separated from expanded polystyrene materials. OSG p107 *

 

[amberleaf]

“ Extractor Fans “ Extractor fans must be provided with an easily accessible means of switching off the supply 132.15.2 * Electrical Equipment that may cause injury during mechanical maintenance i.e. fans, must be provided with a means to switch off the supply. 537.3.1.1 * All items of current using Equipment must be provided with a functional switching device. 537.5.1.3 * All Electrical Equipment must be accessible for operation, inspection & testing, maintenance and repair. 132.12 *
“ Immersion Heaters “ Extractor Fans An immersion heater must not be supplied by a ring final circuit. p362, 433.1.5 * An immersion heater must be connected to the supply by a double pole linked switch only. The use of a plug top and socket outlet is not permitted. 554.3.3 * An immersion heater must be provided with a thermal cut-out to prevent the water from boiling if the thermostat fails. 554.2.1 * All final circuits must be wired separately from all other final circuits. 314.4 * All Electrical Equipment must be accessible for operation, inspection & testing maintenance and repair. 132.12 *
The R1+R2 test sequence for radial final circuits Securely isolate the supply : Disconnect any bonding connections that could affect the test readings. : Make a temporary connection at the CCU between the phase and cpc of the circuit to be tested :. Using a low ohms continuity test meter measure the resistance between phase and cpc at each point on the circuit also confirming polarity. : The R1+R2 is the reading taken at the furthest point on the circuit. : Re-connect any bonding conductors disconnected for the test. : Remove the temporary connection at the CCU : .

“ Neutral Conductors “
In a TN-S or TN-C-S system the neutral conductor is not required to be switched or isolated when it is known that the supply neutral and earth conductors are connected. 537.1.2 ,537.2.1.1 * In a ccu the neutral conductors and cpc's should be connected to their respective terminals in the same order as the Phase conductors are connected to the mcb's. 514.1.2 * Only a linked circuit breaker that breaks all related line conductors can be used with an earthed Neutral conductor. 132.14.2 * It is assumed that where an installation is supplied in accordance with the Electricity Safety, Quality and Continuity Regulations 2002 the connection between the supply neutral and earth is permanent. 114.1 * The neutral conductor is considered to be a live conductor. * A neutral conductor must not be disconnected before a line conductor and must be reconnected before or at the same time as a line conductor. 431.3 * An Neutral conductor must not be independently fused or switched. 530.3.2 The conductors of a 230v circuit installed within a ferromagnetic enclosure must be arranged so that the phase conductor, neutral conductor and the appropriate cpc of each circuit are contained in the same enclosure. 521.5.2

“ Disconnection Times” under fault 230v final circuits in a TN systems not rated greater than 32A must disconnect within 0.4 seconds conditions. 411.3.2.2 * 230v final circuits in a TT systems not rated greater than 32A must disconnect within 0.2 seconds under fault conditions.If disconnection is made by a fuse or mcb and all extraneous conductive parts are connected to the main equipotential bonding then a disconnection time of 0.4 seconds is permitted. 411.3.2.2 * Under fault conditions in a TN systems circuits over 32A including distribution circuits must disconnect within 5 seconds. 411.3.2.3 * Under fault conditions in a TT systems circuits over 32A including distribution circuits must disconnect within 1 second. 411.3.2.4 *
all 17th stuff

“ Shower Circuits “ All items of current using equipment must be provided with a functional switching device. 537.5.1.3 * Electric showers are not to be installed in zone 0. 701.55 * All circuits in a bath or shower room must be protected by a 30ma RCD. p166 , 701.411.3.3 * All final circuits must be wired separately from all other final circuits. 314.4 * All electrical equipment must be accessible for operation, inspection & testing , maintenance and repair. 132.12 *

“ Lighting Circuits “ Where an installation has only one lighting circuit, the circuit may need to be divided into two circuits to minimize the danger that may arise in the event of a fault. 314.1 (iii) This is a !! Requirment !! for Domestic ← part , P, 17th *

“ Connections & Terminations “ Connections must not be subject to any mechanical stress or strain. 526.6 , 530.4.1 * All screw connections must be accessible 526.3 Through crimp connections do not have to be accessible. 526.3 * Stranded cables ends must be fitted with appropriate terminals or suitably treated. 526.8.1 * Every termination, connection or joint between live conductors including the Neutral Conductor must be made in a suitable Accessory or enclosure. 421.7, 526.5 * Live parts must be contained inside enclosures or behind barriers providing a degree of protection of at least IP2X or IPXXB . 416.2.1 * Switch Lines must be marked brown at their terminations. 514.3.1, p343 * A Neutral Conductor must not be disconnected before a line conductor and must be reconnected before or at the same time as a line conductor. 431.3 *

 

[amberleaf]

“ Cooker Circuits “ Unless specifically labelled or suitably identified, all 13A socket outlets must be 30ma RCD protected. 411.3.3 * All final circuits must be wired separately from all other final circuits. 314.4 * All items of current using equipment must be provided with a functional switching device. 537.5.1.3 * The Building Regulations require that accessories should not be mounted so that it is necessary to lean or reach over a cooker to operate them. * All electrical equipment must be accessible for operation, inspection & testing, maintenance and repair. 132.12 * Socket outlets must be spaced at least 150mm away from gas pipes unless there is a pane of non combustible insulating material separating them. OSG p18 * Cooker circuits rated between 16A and 50A may supply two or more cooking appliances installed in the same room. The cooker switch should be installed within 2m adjacent to the appliance(s). One cooker switch can be used to control more than one appliance. OSG p160 *
the R1 + R2 test Sequence for radial final circuits * Securely isolate the supply . Disconnect any bonding connections that could affect the test readings . Make a temporary connection at the CCU between the phase and cpc of the circuit to be tested. Using a low ohms continuity test meter measure the resistance between phase and cpc at each point on the circuit also confirming polarity. The R1+R2 is the reading taken at the furthest point on the circuit . Re-connect any bonding conductors disconnected for the test . Remove the temporary connection at the ccu .

“ Accessibility “ All electrical equipment must be accessible for operation, inspection & testing , maintenance and repair. 132.12 * All screw connections must be accessible. 526.3 Through crimp connections do not have to be accessible. 526.3 * “ Accessories “ All electrical equipment must be accessible for operation, inspection & testing , maintenance and repair. 132.12 * An accessory is an item of electrical equipment that does not use any current eg a switch or a socket-outlet. p20 * Every termination, connection or joint between live conductors including the neutral conductor must be made in a suitable accessory or enclosure. 421.7 , 526.5 * All accessories must be fitted to an appropriate mounting box. 530.4.2 * A wall mounted socket outlet must be mounted high enough above a floor or work surface to prevent damage to the flexible cord of a plug top. 553.1.6 * Unless specifically labelled or suitably identified, all 13A socket outlets must be 30ma RCD protected. 411.3.3 *
BS-7671 does not give specific heights for accessories. * “ part P “ The Building Regulations require the following : * accessories must be mounted between 450mm and 1200mm from the finished floor level in habitable rooms in new dwellings * the centre of a socket outlet should be a minimum of 150mm above the kitchen work surface * accessories must be installed a minimum of 300mm from the edge of cooker spaces, kitchen sinks and draining boards * accessories should not be mounted so that it is necessary to lean or reach over a cooker to operate them * accessories should be mounted on the building fabric and not on kitchen furniture * socket-outlets supplying washing machines and dishwashers should be installed so that water that may drip from plumbing equipment is unlikely to affect the socket-outlet or plug top *

“ Basic & Fault Protection “ Basic Protection is protection against electric shock under normal operating conditions. , p20 * Fault Protection is protection against electric shock with regard to a failure of basic insulation, p24 * Exposed conductive parts of less than 50mm2 are exempt from fault protection. 410.3.9 *

 

[amberleaf]

“ Prospective Fault Current “ At every relevant point of the installation the pfc must be determined by calculation, measurement or enquiry. 434.1 , 612.11 * Fuses and mcb's must have a breaking capacity greater than or equal to the maximum pfc at the point where the device is installed. 432.1 A lower breaking capacity is allowed if another fuse or mcb with the necessary breaking capacity is installed on the supply side and the energy let-through of both devices will not damage the fuse or mcb on the load side. 434.5.1 , 536.1 * “ Single Phase test Procedure “ Prospective Short Circuit Current ← ← Using a 3 lead PFC test instrument connect BOTH the neutral and earth leads to the neutral and the phase lead to the phase and take the measurement with the power on. * Prospective Fault Current. ← ← Using a 3 lead PFC test instrument connect the phase lead to the phase, the neutral lead to the neutral and the earth lead to earth and take the measurement with the power on. * The greater of the PFC and PSC values ↔ ( Ipf ) ↔ should be recorded on the Schedule of test Results

“ Underfloor Heating “ ● All items of current using equipment must be provided with a functional switching device. 537. 5.1. 3 : ● Electric floor heating must not be protected by electrical separation. 701.753 : part 7 , p – 168 ● All circuits in a bath or shower room must be protected by a 30ma RCD. 701.411. 3. 3 : ● Electric floor heating in a bath or shower room must have a metal enclosure or sheath or a fine mesh metallic grid connected to the CPC of the supply circuit SELV supplies excluded ). 701.735 , p-168 ● All electrical equipment must be accessible for operation, inspection & testing, maintenance and repair. 132.12. : ● For more information on electric floor heating see 554. 4. : 753.1. p-224 : more of this part 2 ps , fri , night more to follow this one “ amber going for a 6 pack

Ps , thanks Guys out of 300 !! ↔ It is nice to be nice ? Electricians did they teach you at Collage to say thank you ? My computer is on Vitamins , many thanks to the big BOSS , for putting up with me , thank you JASON , They Work as Well & and the Non paid staff that helps to run the SHOW . for the all Electricians I would to THANK YOU ALL AMBELEAF ,

“ Radial Final Circuits’ Supplying 13A Socket Outlets “ ● Unless specifically labelled or suitably identified, all 13A socket outlets must be 30mA RCD protected. 411. 3. 3. : ● A radial final circuit supplied by a 20A fuse or mcb must have live conductors with a minimum CSA of 2. 5mm a CPC with a minimum CSA of 1. 5mm and cover a floor area not greater than 50m2 . p-363 , 433.1 : ● A radial final circuit supplied by a 30a /32a fuse or mcb must have live conductors with a minimum CSA of 4.0mm2 a CPC with a minimum CSA of 1. 5mm and cover a floor area not greater than 75mS . An unfused spur supplying one single or double socket outlet can be run in 2. 5mm cable and may be connected to the fuse / mcb in the Consumer Unit . p-363 , 433.1 : ● The number of spurs supplied from a fused connection unit (a switched fused spur) and the size of the cable used to supply the spurs depends on the size of the fuse in the fused connection unit. p-363 , 433.1 :● All final circuits must be wired separately from all other final circuits. 314. 4 : ● All electrical equipment must be accessible for operation, Inspection & testing , maintenance and repair. 132.12 : ● Socket outlets must be spaced at least 150mm away from gas pipes unless there is a pane of non combustible insulating material separating them. OSG p-18 :

 

[amberleaf]

“ Incoming Supply “ 132.1.5.1 : ● A main switch must be provided to cut off the voltage to an installation. 132.15.1 : ● A double pole main switch or linked circuit breaker must be installed as close as possible to the incoming supply at the origin of the installation. 537.1.4 : p-241 : ● If an installation in the United Kingdom does not comply with Chapter 13 of BS-7671 the electricity supplier does not have to provide a supply to the property. p-241 : ● A TN-S supply has separate neutral and protective conductors. All the exposed conductive parts of the installation must be connected to the protective conductor at the main earthing terminal. p-30 , p-33 : ● A TN-C-S supply has a combined neutral and protective conductor. All the exposed conductive parts of the installation must be connected to the combined neutral and protective conductor at the main earthing terminal. This type of system is also known as PME ( protective multiple earthing ). p-30 , p-33 : ● PME submains are not permitted. 543. 4. 9 : ● 230v final circuits in a TN system not rated greater than 32A must disconnect within 0. 4 seconds under fault conditions. 411. 3. 2. 2 : ● Under fault conditions in a TN system, circuits over 32A including distribution circuits must disconnect within 5 seconds. 411. 3. 2. 3 : ● If the maximum Zs value for a circuit in a TN system cannot be met , the circuit may be protected by a 30mA RCD. 531. 3.1 : ● If the maximum Ze value for a TN system cannot be met, the installation may be protected by a 100mA RCD and treated as a TT system. 531. 3.1 : 411. 5.1 : 411. 5. 2 : 411. 5. 3 : ● A TT supply has the exposed conductive parts of the installation connected to an earth electrode which is separate from the earth of the supply. p-30 , p-34 : ● A single RCD protecting a TT system must be installed at the origin of the installation unless the part of the system between the origin and the RCD fulfils the requirements for protection by Class II equipment or equivalent insulation . 531. 4.1 : ● 230v final circuits in a TT system not rated greater than 32A must disconnect within 0. 2 seconds under fault conditions. If disconnection is made by a fuse or mcb and all extraneous conductive parts are connected to the main equipotential bonding then a disconnection time of 0. 4 seconds is permitted. 411. 3. 2. 2 : ● Under fault conditions in a TT system, circuits over 32A including distribution circuits must disconnect within 1 second. 411. 3. 2. 4 : ● For more information about TT systems see 411. 5. 2 : 612.8.1 : It is assumed that where an installation is supplied in accordance with the Electricity Safety, Quality and Continuity Regulations 2002 the connection between the supply neutral and earth is permanent. 114.1 : ● The incoming supply to a ↔ Domestic property ↔ is 230v with a permitted tolerance of + 10% / - 6% i.e. 216. 2v - 253. 0v . p-242 : OSG , P-17 : ● Meter tails are part of the consumers installation and are to be provided by the installer. Meter tails must be sheathed and insulated or if insulated only must be enclosed in trunking or conduit. Meter tails must be 25mm2. Where the meter tails are protected against fault current by the main fuse the installation method, maximum length and minimum cross sectional area must meet the distributors requirements. OSG , P-17 : 521.10.1 : ● Meter tails 521.10.1 : 530. 3. 4 : 434.3 : 521.14. 3 : for Domestic part p , ←
“ Distribution Circuits “ ● A distribution circuit is the circuit that connects the incoming supply to the CCU i.e. meter tails. When a distribution circuit supplies an installation remote from the incoming supply it is sometimes referred to as a sub main. P-23 : ● Under fault conditions in a TN system, circuits over 32A including distribution circuits must Disconnect within 5 seconds. 411. 3. 2. 3 : ● Under fault conditions in a TT system, circuits over 32A including distribution circuits must Disconnect within 1 second. 411. 3. 2. 4 :

“Insulation “ Resistance ● SELV & PELV circuits must have a minimum insulation resistance of 0. 5MΩ when tested at 250v dc. with all current using equipment disconnected. 612. 3. 2 : ● Circuits up to 500v must have a minimum insulation resistance of 1.0MΩ when tested at 500v dc with all current using equipment disconnected. 612. 3. 2 : ● These values are considered satisfactory. 612. 3. 2 : ● These values do not apply to fire detection systems. 612. 3. 2 : ← ← ← read this one , ● The insulation resistance must be measured between live conductors (including the neutral ) and between live conductors and the cpc connected to earth. 612. 3. 1 : ● If the circuit contains devices that may be damaged by the test, only a test between the live conductors connected together and the cpc connected to earth is necessary. 612. 3. 3 : ← ← ← read this one

 

[Sparky Bones]

I am a new 'sparky' and my training has gone well, but I need a bit of help passing 2330-203
I am trying to find our some old papers etc so that I can get my mark up. I got 98% on the health and safety but only 53% on the electrical principles.

Can anyone send me some old papers so I can get this mark up?
Thanks

 

[Mac]

I am a new 'sparky' and my training has gone well, but I need a bit of help passing 2330-203
I am trying to find our some old papers etc so that I can get my mark up. I got 98% on the health and safety but only 53% on the electrical principles.

Can anyone send me some old papers so I can get this mark up?
Thanks

Hi and welcome to the forumThere maybe someone along later on to help you

 

[amberleaf]

● Earthing & Equipotential Bonding ● ● Before an addition or alteration can be made to an existing installation it must be ascertained that the earthing and bonding arrangements comply with the current version of BS 7671 and any existing equipment including the incoming supply is adequate for the proposed addition or alteration. 131.8 : ● Every installation must be provided with a main earthing terminal. 542.4.1 : ● The main earthing terminal, all bonding conductor connections and connections to an earth electrode must be permanently labelled 'Safety Electrical Connection - Do Not Remove'. 514.13. 1 , : ● Every joint and connection must be accessible. 543.3.3 , 526. 3 : ● All circuits’ must have a cpc that is terminated at each wiring point and at each accessory . 411.3.1.1 : ● Rigid metal conduit and the metal sheath or armour of a cable can be used as a protective conductor. 543.2.2 , 543.2. 5 : ● Where rigid metal conduit or the metal sheath or armour of a cable is used as a protective conductor, a separate protective conductor must connect the earthing terminal of any accessories to the appropriate metal back box. 543.2.7 , 543.7.2.1 : All joints in metal conduit must be continuous. 543.3.6 : ● The cpc of flat cables must be sleeved when the cable sheath has been removed. 543.3.2 : ● Protective conductors must be identified by the colours green & yellow. 514.4.2 The single colour green is not permitted. 514.4.5 : ● In most domestic installations switches are not to be used with a protective conductor. 543.3.4 : ● All exposed conductive parts of a TN installation must be connected to the main earthing terminal. 411.4.2 ● All extraneous conductive parts in an installation must be connected to the main earthing terminal by main protective bonding conductors. This applies to the metallic sheath of a telecommunication cable where permission from the owner of the cable must be obtained. 411.3.1.2 : ● Main Earthing Conductor ● The minimum csa of the main earthing conductor must be determined by the adiabatic equation or selected from Table 54.7 543.1.1. If the adiabatic equation is used, the minimum csa of the main earthing conductor must be 6mm 544.1.1. Table 54.7 suggests a 16mm main earthing conductor for phase conductors with a csa of up to 35mm. : ● The csa of the main earthing conductor where PME conditions apply should be not less than that for a main protective bonding conductor (10mm ) for the same installation 544.1.1. Invariably the electricity supplier will provide a 16mm main earthing conductor for a PME supply in a domestic property. : ● Main Protective Bonding Conductors’ ● ● For TN-S or TT systems the csa of main protective bonding conductors must be a minimum of 6mm and not be less than half the csa of the main earthing conductor. 544.1.1 : ● For a PME system the csa of the main bonding conductors must not be less than that given in Table 54.8 i.e. a 10mm protective bonding conductor for a neutral conductor of 35mm or less. 544.1.1 : ● For a service pipe, the main bonding conductor should be connected as near as possible to the point where the service enters the building. The connection must be before any branched pipe work and on the consumers side of any meter. If possible the connection should be made within 600mm of the meter outlet. Where the meter is outside, the bonding connection should be made at the point of entry of the service into the building. 544.1.2 : ● Main bonding conductors should not be supported by the service pipes they are connected to. 543.3.1 : ● Where a main bonding conductor loops in and out to connect to an extraneous conductive parts the conductor should be unbroken at the connection. 528.3.3 : ● It is not necessary to run a main protective bonding conductor to an incoming service where the incoming service pipe and the consumers pipe work are both made of plastic. If the incoming service pipe is made of plastic and the consumers pipe work is made of metal it is recommended to main bond any metal paperwork. OSG p29 : ● Supplementary Bonding Conductors ● ● Supplementary bonding is not required in a bath or shower room if all the extraneous conductive parts of the installation are connected to the main equipotential bonding. P166 , 701.415.2 : ● It is not generally required to supplementary bond the following : kitchen pipes, sinks, draining boards, metallic kitchen furniture, boiler pipes, metallic parts supplied by plastic pipes or metal pipes to hand basins or wc's ( excluding metal waste pipes in contact with earth ). OSG p31 : ● Earth Electrodes ● → All of the following can be used as earth electrodes : ← Earth rods or pipes ↔ Earth tapes or wires ↔ Earth plates ↔ Underground structural metalwork embedded in foundations ↔ Welded metal reinforcement of concrete embedded in the Earth (excluding pre stressed concrete ↔ Lead sheaths & metal cables coverings provided the following conditions are met ↔ A - the cable covering must be in effective contact with Earth ↔ B - the permission of the cable owner must be obtained ↔ C - the owner of the cable must be able to inform the owner of the installation of any changes to the cable which may affect it suitability as an earth electrode 542.2.1, 542.2.5, ↔ A metal gas or water pipe must not be used as an earth electrode. 542.2.4 :

 

[amberleaf]

● Cannot be used as a source for a Selv or Pelv System , AUTO-Transformers ← ♫♫♫
What is the MAIN danger with AUTO-Transformers
They can Introduce the Primary voltage onto the Secondary Output terminals during short-circuit

→ CARE MUST BE TAKEN AS DEATH, INJURY AND/OR DAMAGE to equipment may result ←
● 230v ↔ 24v ↔ 230v ●

● New ↔ European Legislation Requires ↔ ALL fire extinguishers to be the same colour.
the main body of all fire Extinguishers is ↔ Red ← ( ? they did something right ,

● Some Revision A Residual Current Device is used to provide Supplementary protection against direct contact and has
A residual operating current of 30mA , if a test current of 15mA is applied between phase & earth
At the output terminals of the device it should :
Not operate within ( 2 sec ) HOW TO REMMBER 30mA ÷ 15mA = 2s

City & Guilds 2392-10

The Purpose of an Electrical Installation Certificate is to provide a formal Assurance from those Responsible
For the Design , Construction , and Inspection and Testing of new Installation work ) including Alterations’ and additions to Existing Installations ) that the Work Complies with National Standard for the Safety of
Electrical Installations , and is therefore Safe to put into Service ,
“ Initial Verification “ The wiring regulations are clear about the requirements of inspection and Testing. The Requirement to carry out an 'Initial Verification' for all New Installations, whatever the size of the work carried out, is included in the fundamental principles of the wiring regulations in regulation 134.2.1.

 

[amberleaf]

Bell Circuits : ● All electrical equipment must be accessible for operation, inspection & testing , maintenance and repair. 132.12 : ● Extra Low Voltage circuits should not be run in the same wiring system as 230v circuits unless all ELV cables and conductors are insulated for 230v or separated by an earthed metal screen. 528.1 : ● All items of current using equipment must be provided with a functional switching device. 537.5.1.3. : ● Eddy Currents : ● To avoid eddy currents, conductors of an ac circuit should not be installed in separate steel conduits. 521.5.2 : The conductors of a 230v circuit installed within a ferromagnetic enclosure must be arranged so that the phase conductor, neutral conductor and the appropriate cpc of each circuit are contained in the same enclosure. 521.5.2 : ● Single core armoured cables must not be used in an a.c. circuit. 521.5.2 : ● Telecommunication Circuits : BS 7671 does not provide detailed information on telecommunication circuits and is supplemented by BS 6701. p12 : ● All extraneous conductive parts in an installation must be connected to the main earthing terminals by main protective bonding conductors. This applies to the metallic sheath of a telecommunication cable where permission from the owner of the cable must be obtained. 411.3.1.2 : ● Telecommunication cables and power cables must not be run together. 528.2 : Extra Low Voltage circuits should not be run in the same wiring system as 230v circuits unless all ELV cables and conductors are insulated for 230v or separated by an earthed metal screen. 528.1 :

 

[amberleaf]

“ Operation less than “

Type No , 100millisecnds ( Instantaneous ) 433.1 States that “ Provided an Overload Protective Device .
(B) Between 3 and 5 times rated current Protection against Short-Circuit
(C) Between 5 and 10 times rated current
(D) Between 10 and 20 times rated current

Every Circuit shall be designed so that a small overload of long duration is unlikely to occur

selv & felv

SELV and FELV are two totally different beasts .

110 V single phase, fed from a transformer, often with an earthed centre-tapped secondary winding, to feed transportable tools and equipment, such as floodlighting, with a load of up to 2 kW. This supply ensures that the voltage to earth should never exceed 55 V (see The primary winding of the transformer must be RCD-protected unless the equipment fed is to be used indoors.

Supplies will normally be obtained from the Electricity Supply Company. Where a site is remote, so that a generator must be used (IT supply system) special protective requirements apply which are beyond the scope of this Guide, and the advice of a qualified electrical engineer must be sought. Attention is drawn to BS 7375: 1966 Code of Practice for the distribution of electricity on construction and building sites.

The equipment used must be suitable for the particular supply to which it is connected, and for the duty it will meet on site. Where more than one voltage is in use, plugs and sockets must be non interchangeable to prevent misconnection. Six levels of voltage are recognised for a construction site installation. They are:

25V single-phase SELV for portable hand-lamps in damp and confined situations,
50V single-phase, centre-point earthed for hand lamps in damp and confined situations,
400V three phase, for use with fixed or transportable equipment with a load of more than 3750 Watts,

230V single phase, for site buildings and fixed lighting ----
110V three phase, for transportable equipment with a load up to 3750 Watts, and

110V single phase, fed from a transformer, often with an earthed centre-tapped secondary winding, to feed transportable tools and equipment, such as floodlighting, with a load of up to 2 kW. This supply ensures that the voltage to earth should never exceed 55 V (see {Fig 7.5}). The primary winding of the transformer must be RCD-protected unless the equipment fed is to be used indoors.

“ Safety Service “ Chapter 56 p /151

560.6.7
1 ,Where a generating set is used as an additional source of supply in parallel with others sources ,
Protection shall remain effective in all situations against overcurrent and ←

● Answer , the time it takes for safety source to supply the power to the safety service ,
After the loss of the main power supply ,

2 , Regarding Auxiliary supplies to Safety Services , the maximum changeover time refers to : ←
● Answer , the time it takes for the Safety Source to Supply the power to Safety Service , after the loss of
The main power Supply ,
“ This is what the 17th is asking you “

537.5

537.5.2
Functional switching devices : ● generally required to be capable of switching the Load “ on and off “
537.5.1.4
Definition Functional Switching ●

“ Equipment may be used controlled either manually or automatically “

( 1 ) A Time switch is an example of an automatically-operated functional switch ●
( 2 ) A switch in a socket-outlet ●
( 3 ) A contactor switching the supply to start and stop an electric motor ●
( 4 ) A push buttons used to control a contactor or relay ●
( 5 ) A thermostat used to switch an immersion heater “ on “ and “ off ●
( 6 ) A pressure switch or level switch used a pump on and off ●
( 7 ) A Lighting switches and dimmers ●

( Functional switching devices do not necessarily have contacts that open & close
Opening contacts are not essential ,

537.5.2.1.
Functional switching devices shall be suitable for the most onerous duty they are intended to perform ,
● Should be selected to have a utilization category Appropriate to the Type of load being Switched , ←

537.5.2.3.
Off-Load isolators ( disconnectors ) fuses and links shall not be used for Functional Switching ,
● NOT to be used for this Purpose , C/G ← ←

 

[amberleaf]

C/G are bring out a New Certificate , for Confined Spaces , → → on September 2009 ←←

“ Earthing & Cable Things “
● When two Bonding Conductors of Equal Length are Connected in Parallel the Resistance would , ( Halve ) ←
● The Resistance of a Bonding Conductor will Increase if , ( the Length Increases ) ←
● An Earth Loop Impedance Tester should only allow current to flow for , ( 40mS ) ←
● A Reference Method Indicates , ( The Instillation Method ) ←
● the Value will Decrease as we move Farther away from the Intake Position ( Resistance Increases with Length )
● A final circuit is the wiring between the ( Distribution Board and Current using Equipment ) ←
● The Effects of Creating a Ring Final Circuit would be that the Overall Resistance of the Conductors would ( Decrease ) ←
● When Applying the rule of thumb method , the value of Prospective Short-Circuit Current for a 3 Phase Supply should be ,
( Twice the Single Phase Value ) ←

With many thanks I would Like to say thank you for a First Class Forum . Amberleaf
You professionalism is second to nun ,

 

[amberleaf]

● if you Double the Length of Wire ( you will Double the Resistance of the Wire ) ←
● if you Double the Cross-Sectional Area of a Wire you will Cut its Resistance in ( Half ) ←
● The Resistance in Ohms , of a Conductor , ( Increases with Increase of Cable Length ) ←


Regulations 434.1 / 612.11

● Require that the Prospective Short Circuit Current and the Prospective Earth Fault Current are Determined ,
Once Determined , The Highest Value Must be Record , ( PSCC ) ( PFC ) Ia / Ief

● A Prospective Short-Circuit Current is the Maximum Current that Could flow Between ● Phase and Neutral Single–Phase Supply ,

● A Prospective Earth Fault Current is the Maximum Current that Could Between Live Conductors and Earth ,

● The Higher of these Value is know as Prospective Fault Current ,

● the High Prospective Fault Current will be at the Origin of the Installation and must be Measured as Close to the Meter Position
As Possible , Usually at the Main Switch for the Installation , it is Measured between Phase and Neutral ,

● Enquiry to the Suppler ,
● Calculation ,
● Measurement ,

● Enquiry ,
Phone Call to the Electricity Supplier of the Installation ,
That will tell you the Maximum ( PFC ) Usually this is a Lot Higher than the Value will Actually be ,

● Calculation ,
The ( PFC ) can Only be Calculated on a ( TN-C-S Systems ,
The Neutral of the Supply is Used as a Protective Earth & Neutral ( PEN ) Conductor , ≈≈≈≈≈≈

When the Earth Fault Loop Impedance is Measured ,
The Value Measured is in Ohms ,
To Convert this Value to Prospective Short-Circuit-Current ( PSCC ) we must Use the following Equation ,

V Ze > Measured – 0.28Ω 230 ÷ 0.28 = 821A
( PSCC ) = ------ = I
Ze

● Measurement ( kA )
This is Carried out Using a Prospective Fault Current Tester ,
Measurement of ( PFC ) is taken as Close to Supply intake as Possible ,

● Measurement ( Ohms )
Measurement Value , 0.08Ω

Uoc - 230v
230v
( PSCC ) = -- ÷ -- = 2875A
0.08 Ω

Measurement of ( PFC ) if taken Close to the Supply intake as Possible ,
All Protective Devices fitted in the Installation have a Short Circuit Capacity
That is Higher than the Measured Value , ( 432.3 will be Satisfied ,

( Jason what is my P/Qs please , Amberlaef , can you send me a Email , 11/6/09 )