Discuss ***Cont../ Useful Information for Electricians & Apprentices*** in the Australia area at ElectriciansForums.net
O.S.G.. The use of other methods’ of determining Maximum Demand is Not Precludedwhere Specified by the Installation Designer
FirstlyI make no Apologies for the Way am Writing on any Matters . it can be a first day Apprentice or some one Needing aJog of Memory .
Sowe are all in the Same Boat . “ To Learn “
For the Apprentices . The Day we stop learning is the Day we hang Upour Tool-Bag
CookerDesign Current Calculations
Thefirst thing you have to do is get Your Head around the Calculations !!
(From a Design point of View ) 2392-10
DomesticInstallation Oven(s) & Hob(s) are to be Calculated upon their MAXIMUM LOADING
Startwith a simple Calculation ( An Oven has a rating of 2kW ) 2000
(I = P/V ) Formula … I = 2000 ÷ 230V = 8.70A …. Weare Using the Unit Amps
2392-10/ Domestic Installation Oven(s)
Ovenhas 4 Rings ( 2 x 1kW ) & ( 2 x 1.5kW ) & Grill ( 2kW ) & Oven (3kW )
-Controlled via a CookerSwitch with a Socket outlet .
Asa Designer . we’ll have to Apply Diversity ??
Important )- Diversity allowance to be Applied to the FULL LOAD CURRENT for CookingAppliances .
TheO.S.G. is telling us . Purpose of the Final Circuit fed from theConductors )
O.S.G.Table 1B p/97 – column (3) Cooking Appliances → At the Top of the Page Note : Type ofPremises ( 2392-10 → Household Installations ) Domestic Installation(s)
DomesticInstallation(s) Only O.S.G. - 10A + 30% f.l – Full Load ) of connected Cooking Appliances in the Excess of 10A+ 5A if a socket-outlet is incorporated in the Control Unit . ( C.C.U. ) – 45A + 13A Socket Switched with Neon .
Fromyour point of View ( The First 10A ofthe rated current plus 30% of the reminder ( Plus) 5A if the Control Unit incorporates s Socket.
Calculations)- You bank “ Hold OFF“ the first 10 Amps of the Maximum Load Current )
The10A will be used at the End of the Calculations’
-So your Work out the Total Power Rating & then calculate the Full Load Current
Calculations)- Power = ( 2 x 1 ) + ( 2 x 1.5 ) + ( 2+ 3 ) = 10kW
I= 10000 ÷ 230V = 43.48A … round it up to the first four numbers43.47826087 ( 48 ) 43.48A
UsingDiversity allowance stated ↑↑ ( 43.48A sub 10A = 33.48A )
I= 33.48 x 30 ÷ 100 = 10.04A
Youradding the ( 5A ) for Socket outlet . I = 10A + 10.04 + 5A = 25.04A )- Asa Designer this is your Expected Current Demand .
Remember )- Supply Cables Rated to suit DesignCurrent ( Iz ) 
2392-10: :aureola:
Statethree different types of Protective Conductorthat are commonly connected to the Main Earth Terminal ( MET ) of an Electrical Installation .
i)Earthing Conductor .
ii)Circuit Protective Conductor .
iii)Main Protective Bonding Conductor .
Self-employed Electricians going to working in Industry . :crazy:
The Pop Up machines now come under the ( PAV ) Category ( Push Around Verticals )
Which also includes the ( 1a ) Category .This course can be done solely for these .
But be more advantageous for you to dothe ( 3a ) Category ( Scissor Lifts ) whichwould also cover you for using the ( PAVs ) and any in the ( 1a ) Category . proving that you have had “Familiarisation “ on them .
What your needing . ( PAL ) Powered Access Licence .
Type ( 3a / 3b ) ◄◄
IPAF : ( 1 person ) One Day Course .Training £ 228.00 – Vat paid
Lasts : 5 Years .
This will show you the Machines to Use . WWW.ipaf.org
FourDocument that the ( Inspector ) may need to consult during the Inspection& Testing procedures . :vanish:
BS-7671:2008.
IET– Guidance Note – 3
IET– On – Site – Guide .
TheElectricity Safety Quality & Continuity Regulations 2002 .
Inspection& Testing of Electrical Installations . :vanish:
Usingdiagrams to support your answer explain the three steps required to perform aContinuity of Ring Final Circuit Conductors Test.
Explainany precautions & checks you would make before starting the Test .
Using (- A Low résistance ohm-meter continuity tester will beused for this Test .
WithTest Leads & Probes conforming to HSE . GN-38
Beforeany measurements are taken the résistance value of the Test Leads .
&Probes are noted & this value is subtracted from any Test Results . Alternatively if the Test Instrument has anAuto null facility this should be applied before any measurements are recorded.
Withthe electrical installation safety Isolated& Proved Dead.
Indentify& disconnect the Line . Neutral . & CPCconductors of Ring Final Circuit at the Distribution Board .
Measure& Record the End to End résistance of the following.
Therésistance of the Phase to Line Loop = (r1 )
Therésistance of the Neutral to Neutral loop = ( r/n )
Therésistance of the CPC to CPC loop = ( r2 )
Thevalues of ( r1 + r/n ) & r2 willindicate whether the conductors are continuousor not .
A FiniteSmall reading will indicate the conductors are continuous .
A high Résistance value will indicatethe conductors are Open Circuit . or Faulty . orConductor terminations are loose .
TheLine & Neutral conductors both being typically 2.5mm[SUP]2 [/SUP] should have equal values of résistance:- Measured within 0.05Ω of each other .within 0.05Ω
Wouldalso apply if the Ring Final Conductors were larger ( 4.0mm[SUP]2 [/SUP] ) CPC being 1.5mm[SUP]2 [/SUP] . for
2.5mm[SUP]2 [/SUP] / 1.5mm[SUP]2 [/SUP] T&E - has a smaller Cross-sectional area than theLine 2.5mm[SUP]2 [/SUP] conductors . As suchthe CPC résistance will slightly higherthan the Line conductors’ .
2.5mm[SUP]2 [/SUP] / 1.5mm[SUP]2 [/SUP] T&E - The résistance of the CPC should beapproximately ( 1.67 times ) greater than the résistance of the Line conductors.
Performa quick calculation to check the Expected value of the CPC is approximately ( 1.67times ) larger than the Line Conductors .
Whattype of Inspection & Tests . Will be required for the ElectricalInstallation within this building . ??
Forthe ( NEW ) Electrical Installation . an InitialInspection Test & Verification
Forthe ( Existing ) Electrical Installation . anPeriodic Inspection report & Test .
Listall the relevant documentation that need to be competed for this ElectricalInstallation . ??
( 2392-10 ) ► New ◄ Electrical Installation
i)Electrical InstallationCertificate .
ii)Schedule of Inspections .
iii)Schedule of Test results .
thistake you into 2391-10 ) ( Existing ) Electrical Installation
i)Periodic Inspection Report for an Electrical Installation
ii)Schedule of Inspections .
iii)Schedule of Test results .
Twopossible conditions that may have an Effect on the Measured value of ( EarthFault Loop Impedance ) :vanish:
i)Ambient Temperature in the locality of thecables Under Test .
ii)The Actual Temperature of the Cables Under Test .
Whatfunction does a Switch perform in the Circuit . :willy_nilly:
ASwitch ( Opens ) or ( Closes) an electrical circuit .
Ifthe Circuit is ( Open ) – NO electricityflows . “ Circuit is broken “
Ifthe Circuit is ( Closed ) - Electricity Flowsthrough the Circuit . 2392-10 ( Can we confirmPolarity ) “ Circuit is complete “
Sowhat is a Polarity Test .
Basicallyit is a Test that creates a Circuit using the Line conductor & the singlepole device in question . Breaking the circuit when Operating the device . means that the reading on theInstrument will Change .
&thus confirming that device must be connected in the Line Conductor .
Test to Ensure that all singlepole devices ( Fuses . Switches . & Circuit Breaker ) are connected inthe Line Conductor Only .
Switch: Permanent Live. Switch Live .
Switching T&E . You should sleeve the Blue Conductor / with brown sleeve .to say it is being used as a Switch Wire .
UsefulJunk .
Metal is Used in Switches because most Metals are Good Conductors of “ Electricity “
DomesticInstallation
Whatis - Circuit Control from a Testers point of View ? :willy_nilly:
Itis Vital that any Circuit . NO matter its levelof complexity . ( Can be Controlled )
Asimple Switch :- allowing us to turn the CircuitOn or Off .
Regulation/ Definitions – p/26 . Wording
Isolation :- “ Function “ .
Afunction intended to Cut Off for reasons of safety the supply from all . or a discretesection . of the Installation by separating the Installation or Section fromevery source of Electrical Energy .
Isolator :- “ Disconnector “
AMechanical Switching Device which . in the ( OpenPosition ) complies with the requirements specified for the Isolationfunction in part 2 of BS-7671 .
Note : it also States a“ a “ Isolator “ is otherwise known as an “ Disconnector “
Sourceof Supply .
Oftena circuit is Thought of as being the ( Load )& the conductors supplying the ( Load )
InReality they are only ( Part of the Circuit ) inorder for Current to flow two conditions have to be met .
i)There has to be a ( Potential Difference ) applied across the circuit ( Voltage )
ii)There has to be a ( Complete Circuit ) “Circle “ for current to flow around .
A Source of Supply can be ( A.C. or D.C. )
Apprentices.
Determiningthe Protective Device characteristics forCircuits . ??
ElectricalInstallation Design .
Allyou need to know is to use the given details to select the Appropriate Protective Device for a given circuit .
Themain formula we can start with .
Iz > = In > = Ib .
Ib (- design current of circuit ( A ) The loadto be connected to the circuit .
In (- Nominal current of the Protective Device ( A )
Iz (- Effective current carrying capacity ( A )
Thismeans that in every circuit at all times the current carrying capacity of thecables must be ( Higher ) than the highestpossible load current .
Also. the Protective Device rating must be ( Higher) than the load current but lower than the maximum current carrying capacity ofthe cable installed .
As-&-s are touchy about RCDs .
AResidual Current Device ( RCD ) will . ??
i)Operate if a Short Occurs between Line & Neutral
ii)Operate if a Small Overload occurs .
iii)Operate if Line& Neutral are out of Balance . ◄◄ “ Resi/ dual “ . Two Words - Line & Neutral
2392-10(- Q )- . An Overload Current is . ?? Regulation p/27 – A )- . An overcurrentoccurring in a circuit which is Electrically Sound . :6:
Thetype of Fault which occurs when a Line conductorcomes in contact with a Neutral conductor is called? ( ShortCircuit Fault ) :willy_nilly:
Regulation Red book 2008 : Chapter 53 :speechless:
Protection. Isolation . Switching . Control & Monitoring .
Regulation:- The “ Term “ Isolation & Switching – as used in BS-7671 ( Refers to four distinct functions )
i) Isolation
ii)Switching OFF for mechanical Maintenance .
iii)Emergency Switching &
iv) Functional Switching
Referto Table 53.2 – p/117
2392-10:- “ Consumer Controlgear “ 530.3.4. :speechless:
ForInstallation with a 230V single-phase supplyrated up to 100A that are under the control of ( Ordinary Persons) should either .
• Comply with BS-EN 60439-3 & Regulation 432.1. of BS-7671.
• Be a Consumer Unit – incorporating components complyingwith BS-EN 60439-3
Regulation Chapter 532 . :- Devices for Protectionagainst the Risk of Fire . :whatchutalkingabout
532.1.Where in accordance with the requirement of Regulation 422.3.9. it is necessaryto limit the Consequence of ( Fault Currents )in wiring system from the point of view of ( Fire Risk ) THE Circuitshall be either .
i)Protected by an RCD complying with Regulation 531.2. for ( Fault Protection ) &
- The RCD shall be installed at the ( Origin of the Circuit ) to be Protected . &
- TheRCD shall Switch all Live Conductors . &
-The rated Residual Operating Current of the RCDshall Not Exceed ( 300mA) ETC .
Chapter537 . Isolation & Switching .
Isolation– ( 537.2.
Switchingoff for Mechanical Maintenance - ( 537.3.
EmergencySwitching - ( 537.4 .
FunctionalSwitching - ( 537.5.
Fire-fighter’s Switches – ( 537.6 . :speechless:
A Fire-fighter’sswitch shall be provided in the Low Voltage circuit supplying :
i)( Exterior ◄ ) electrical installationsoperating at a Voltage Exceeding Low Voltage . &
ii)( Interior ◄ ) Discharge lighting installations operating ata Voltage ( ExceedingLow Voltage )
(Temporary Installation ) Fire-fighter’s Switches – ( 537.6.1.
Forthe purpose of this regulation . An installation in a CoveredMarket . Arcadeor Shopping Mall is considered to be an (Exterior Installation )
• A Temporary Installation in a Permanent Building used for Exhibitions isconsidered ( NOT to be an Exterior Installation )
“ Isolation“ :icon14:
Itemsto be Considered in Relation to “ Isolation “ devices.
• Number of poles to be “ Isolated“
• “ Isolation “ of groups &inconvenience .
• Devices designed and / orinstalled to prevent Unintentional or Inadvertent closure .
• “ Isolation “ devices to beClearly Indentified and Indicate the Installation or Circuit it Isolates .
Isolationrequirements for ( TN-S ) Systems .
Single-phase. L ≈ N - Circuit Protective Conductor .
Three-phase. L1 . L2 . L3. ≈ N . - Circuit ProtectiveConductor .
Reply to ***Cont../ Useful Information for Electricians & Apprentices*** in the Australia area at ElectriciansForums.net
