***Cont../ Useful Information for Electricians & Apprentices***

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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 )

 

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Apprentices :

RCDs / are NOT designed to break the ( High ShortCircuit Currents ) Which may Occur in Domestic Wiring Installations &must be Used with an Over-Current Protection Device “ Such as MCB “

RCD reacts to currentleaking from Line to Earth & an MCB reacts to Excessive Current . :icon14:

RCCBs . Residual Current Circuit Breakers /Which provide Earth Fault Protection only .
RCBOs . Residual Current Circuit Breakers / WithOverloadProtection : Which provides Earth Fault . Overload & Short-Circuit Protection

Apprentices : What is an RCBO - RCD / MCB .
RCD – Side Earth Fault . reactsto current leaking from Line to Earth / Faults

RCBOs . if welook at an ( RCBO ) B / Curve 30mA
RCBOs . if welook at an ( RCBO ) C / Curve 30mA

RCBOs .Respond to both ( A.C. ) & Pulsating ( D.C..) Residual Currents &are Manufactured to Comply with BS-EN 61009-1

Manufactured(- The Single Module ( RCBO ) is an Electronic Unit designed specificallyfor fitting into ( Plastic & Metal ) & Distribution Boards to give ( Earth Leakage Protection ) to an IndividualCircuit .
:earmuffs:

 

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2392-10:

UsefulJunk . RCBO. :speechless:

Thethin white wire ( Earth Cable ) is purely there as a ( Back Up ) incase of a Loss of Neutral .

The Good News . Unfortunatelyits Not Possible to ( Disable ) or ( By-pass ) the RCD functionon a RCBO .

 

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2392-10 Practical Assignment ( -&-s Exam : To be Used only for MinorElectrical Work which ( Does Not ) include the (Provision of a New Circuit ) :53:

2392-10
Completionof Minor Electrical Installation Works Certificate .

The Minor Works Certificate is intended to be Used for Additions & Alterations toan installation that Do Not extend to the provision of a New Circuit .
ThisCertificate may also be Used for the Replacement of Equipment suchas Accessories or Luminaries.

2392-10 p/336 .
Appropriate Inspection & Testing . should always be carried out ( Irrespective ) of the extent of the Work Undertaken .

• Part / 1 : Description of Minor Works .
( 1 / 2 ) The Minor Works be so described that the workthat is the subject of the Certification can be ReadilyIndentified .
1) Description of the Minor Works .
2)Location / Address .

4)Regulation ( 120.3& 120.4 ) Nodepartures are to be ( Expected Except in most UnusualCircumstances ) Regulation 633.1.
Part4 (- I/We Certify that the said works donot impair the safety of the existing installation . Etc .

• Part / 2 : InstallationDetails .

2) The method of FaultProtection must be clearly indentified .
“ System “ Earthing Arrangement. TN-C-S . TN-S . TT .
Automatic Disconnection of thesupply using ( Fuse . Circuit/Breaker . RCD .

4)if the Existing Installation ( LACKS ) either aneffective means of Earthing or Adequate Main Protective Bonding Conductor . this must beclearly stated . Regulation . 633.2.
EarthingConductor : Distribution / MET – 16.0mm[SUP]2 [/SUP] ???
RecordedDepartures from ( BS-7671:2008 ) May constitute( Non-compliance) with the Electricity Safety . Quality & Continuity Regulations 2002 ( asamended ) or the Electricity at Work Regulation 1989 .

2392-10 as a Tester .
It is Important that the client is Advised Immediately in Writing .

Commentson ( Existing Installation ) including adequacyof Earthing & Bondingarrangements . Regulation 131.8 .

• Part / 3 : Essential Tests )

Therelevant provisions of ( Part 6 ) Inspection & Testing of BS-7671:2008 / Red cover .

Mustbe Applied in Fullto all Minor Works .
• Here’s you Example . Where aSocket outlet is added to an Existing circuit it is Necessary to . ??

i)Establish that the Earthing Contact of the Socket outlet is connected to the ( Main Earthing Terminal )
ii)Measure the ( Insulation Résistance ) ofthe circuit that has been added to . & establish that it complies with ( Table 61 of BS-7671:2008)
iii)Measure the ( Earth Fault Loop Impedance ) toestablish that the Maximum permitted Disconnection Time is NOTExceeded .
iv) • Here’s you Example . )- Check that the Polarity of the Socket outlet is Correct .
v)if the Work is Protected by an ( RCD ) verifythe Effectiveness of the ( RCD )

• Part / 4 : Declaration .

1/ 3 ) : The Certificate shall be madeout & signed by a ( Competent Person ) I respectof the Design . Construction . Inspection & Testing of the Work .
1/ 3 ) : The ( CompetentPerson ) will have a sound knowledge & experience relevant to thenature of the Work undertaken & to the Technical standards set down in ( BS-7671:2008) be fully ( Versed in the Inspection & TestingProcedure ) contained in the Regulations &Employ adequate ( Testing Equipment )

2)When making out & signing a form on behalf of a Company or other Businessentity . State for whom they are Acting. :34:

 

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2392-10:
DirectMeasurement of ( Zs ) can only be made on a LiveInstallation . ( Live Test ≈ ) :speechless:

Neitherthe ( Connection ) with Earthnor Main Bondingconductors are ( Disconnected ) The reading given by the ( Loop Impedance Tester ) will be Less than ( Ze) + ( R1 + R2 ) because of ) Parallel Earth Return Pathsprovided by any Bonded Extraneous-conductive-parts.

 

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TheExternal Impedance ( Ze ) be measured using (Earth Loop Impedance Tester ) :svengo:

TheMain Switch is opened & made secured to disconnect the Installation fromthe source of supply .
The( Main Earthing Conductor ) is disconnectedfrom the ( Main EarthingTerminal ) & the measurement made between( Line ) & ( Earth) of the supply .

Pointto Note : ( Ze ) is Measured using an Earth FaultLoop Impedance Tester at the ( Origin of the Installation )

Pointto Note : GN-3 : ( 3) p/50
542.4.2.(- The impedance measurement is madebetween the Line of the Supply& the means of Earthing with the ( Main Switch Opened ) OR
Withall ( Circuits Isolated )

From-&-s point of View .
Careshould be Taken to Avoid any Shock Hazards’ to the Testing Personnel & otherspersons on both whilst establishing contact .

Note : -&-s (- Parallel Paths . Yeah . 610.1. :nono:
Note : -&-s (- Themeans of Earthing must be DISCONNECTED from theINSTALLATION Earthed Equipotential Bondingfor :nono:
Note : -&-s (- Ensurethat the EARTHING CONNECTIONS has been REPLACED before RECLOSINGthe MAIN SWITCH . ◄◄ :nono:

 

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2392-10 Practical Assignment ( The Regulation are Reinforcing this Matter ) Not – Energised Yet ) Dead / Testing . :hurray:

2392-10: Notes on Schedule of Test Results . p/341 . Learning Curve . :46:

1)Type of Supply isascertained from the distributor or by ( Inspection)
2)( Ze ) at origin .
Whenthe maximum value declared by the Distributor is( Used ) the effectiveness of the Earth must be Confirmed ( Bya Test )
Ifmeasured the MainBonding will need to be ( Disconnected )for the Duration of the Test. ◄► ( ONLY )

3)Prospective FaultCurrent ( PFC )The value ( Recorded ) is the Greater of Either the ( Short-Circuit Current ) OR
TheEarth Fault Current ( The Highest on the Schedule of Test Results ) -&-s . 2392-10 . Exam :driving:

4)Short-circuit capacity of the device is noted .

( T ) The following Tests . Where relevant . shallbe carried out in the following sequence .

612.2.1. Continuityof Protective Conductors . including Main& Supplementary Bonding . ( When Required ) Etc
-&-s. Every Protective Conductor – should be Tested to verify that it is ( Continuous& Correctly Connected )

6)Continuity :
Where( Test Method 1 ) ◄► is Used enter the MeasurementRésistance of the Line Conductor plus the ( Circuit Protective Conductor ) - ( R1 + R2 ) look. GN-3
Duringthe Continuity Testing ( Test Method 1 ) ◄ The following ► ( Polarity Checksare to be Carried OUT )
( Polarity / i) Every fuse & single-pole control &protective device is connected in the Line conductorONLY . ► ( 612.6. )
( Polarity / ii) Centre-contact bayonet & Edison screw lampholders have outer contact connected tothe ( Neutral Conductor ) ► ( 612.6. )
( Polarity / iii) Wiring is correctly connected toSocket Outlet & similar accessories . [ Compliance is to be Indicated by a ( Tick )column / 11

( R2 ) is recorded in Column 7 . ( I put this in for Apprentices / ( PIR ) Wander Leads . Methods . 612.2.1.

Where( Test Method 2) is used . The maximum values of ( R2 ) isrecorded in column 7 . ( Get yourself acopy of GN-3 ) it Helps a Lot .

8)Continuity of the Ring Final Circuit Conductors . 612.2.2.
A testshall be made to ( ►Verify ◄ ) the Continuity of ( EACH) conductor including the ( Protective Conductor) of every Ring Final Circuit .

► 9) 10 ) Insulation Résistance .( IR )
Allvoltage ( Sensitive Devices ) to be Disconnected ◄◄612.3.3. plus – Note
Ortest between ( Line & Neutral ) connected together & Earth . TheInsulation Résistance between ( Live Conductors ◄►) Column 9 / Line / Earth – 10

 

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WordingRectified ( Sorry) ◄◄◄ :rolleyes2:

2392-10 Practical Assignment ( The Regulation are Reinforcing this Matter ) Not – Energised Yet ) Dead / Testing . :juggle:

( T ) The following Tests . Where relevant . shallbe carried out in the following sequence .

612.2.1. Continuityof Protective Conductors . including Main& Supplementary Bonding . ( When Required ) Etc
-&-s. Every Protective Conductor – should be Tested to verify that it is ( Continuous& Correctly Connected )

6)Continuity :
Where( Test Method 1 ) ◄► is Used enter the MeasurementRésistance of the Line Conductor plus the ( Circuit Protective Conductor ) - ( R1 + R2 ) look. GN-3
Duringthe Continuity Testing ( Test Method 1 ) ◄ The following ► ( Polarity Checksare to be Carried OUT )
( Polarity / i) Every fuse & single-pole control &protective device is connected in the Line conductorONLY . ► ( 612.6. )
( Polarity / ii) Centre-contact bayonet & Edison screw lampholders have outer contact connected tothe ( Neutral Conductor ) ► ( 612.6. )
( Polarity / iii) Wiring is correctly connected toSocket Outlet & similar accessories . [ Compliance is to be Indicated by a ( Tick )column / 11

( R2 ) is recorded in Column 7 . ( I put this in for Apprentices / ( PIR ) Wander Leads . Methods . 612.2.1.

Where( Test Method 2) is used . The maximum values of ( R2 ) isrecorded in column 7 . ( Get yourself acopy of GN-3 ) it Helps a Lot .

8)Continuity of the Ring Final Circuit Conductors . 612.2.2.
A testshall be made to ( ►Verify ◄ ) the Continuity of ( EACH) conductor including the ( Protective Conductor) of every Ring Final Circuit .

► 9) 10 ) Insulation Résistance .( IR )
Allvoltage ( Sensitive Devices ) to be Disconnected ◄◄612.3.3. plus – Note
Ortest between ( Line & Neutral ) connected together & Earth . TheInsulation Résistance between ( Live Conductors ◄►) Column 9 / Line / Earth – 10

 

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Polarity: Red Cover .2008 .

A SatisfactoryPolarity Test . may be indicated by a Tick incolumn 11 . – p341.

( PIR ) / 2391-10(- Only in a Schedule of Test Results associatedwith a ( Periodic InspectionReport ) is it acceptable to record IncorrectPolarity .

2392-10. When your doing a New Installation / Initial Verification . you have Checked Anything. New Design . Yeah . :13:



Polarity: Red

 

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FunctionalTesting . ?? :13:

TheOperation of RCDs . & RCBOs shall be tested by Simulatinga Fault Condition .

i)Independent of any Test Facility in the device .Record operating time . column 13. RCDtime . x1 / mS
ii)Effectiveness of the Test Button must beConfirmed . GN-3

FunctionalTesting ?? . 14 . Other . x5

 

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:leaving:2391-10:

14. All switchgear & Controlgerar Assemblies . Drivers . Control & Interlocks .
Mustbe operated to ensure that they are Properly Mounted . Adjusted . &Installed .

Satisfactoryoperation is Indicated by a TICK . column 14

 

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I got this one on my Exams . ( PIR ) :crazy:

Extent & Limitations of the inspection . Note 5 . ( Limitations / Regulation – 634.2 . :13:

 

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Ihave NOT got . ( First Amendedment ) Green / am working off . Red Edition

2392-10. -&-s are looking for .??? Example . BS-7671: 2008 .333 / 337

ElectricalInstallation Certificate : ( EIC )

ThisReport is only Valid if a Schedule of Inspection(s) & a Scheduleof Test Result(s) . 2 x :leaving:


PeriodicInspection Report : ( PIR ) - To be appended to the Report .

(PIR ) Firstly )- Reporting on the Condition of an Existing Electrical Installation . -&-s :13:

ThisReport is only Valid if a Schedule of Inspection(s) & a Scheduleof Test Result(s) . are appended .

PS.Am not working to NICEIC. Test Sheets

 

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WanderLead ( R2 )

Megger- 1552 . Megger / Wander Lead 50m ( 1.17Ω ) Not Nulledyet . :leaving:

Megger- 1552 . “ Auto – Null “ . 0.00Ω

Apprentices. it is Important to Null out any Lead before you startany work .

TestMethod 1 . Will yield : ( R1 + R2 ) GN-3. p/34
TestMethod 2 . Will yield : ( R2 ) GN-3 .p/35

TestMethod ( 1 & 2) are alternative ways of Testing the Continuity of ProtectiveConductor

Scheduleof Test Results ( R2 )
Scheduleof Test Results ( R1 + R2 )

Two methods may be adopted forthis Test but t is Important to Note : that when Testing the Continuity of ( CPCs ) with respect to ( SupplementaryProtective Bondingconductors . WhereRequired ◄◄ ) & MainProtective Bonding Conductors that in order to avoidParallel Paths .

Parallel Paths / it isnecessary to disconnect one end of the conductor in each Case to Obtain anAccurate value .

Parallel Paths ( Parallel - Circuit(s) has more than One Resistor ( Used as a Figure ofSpeech ) . ( Anything that UsesElectricity to do Work ) Learning Curve.
getsits name from having MultipleParallel Paths . to move along .

TheWhy’s / MultipleParallel Paths - This is done so that Lights don’t stopWorking . Yeah

• Fromthis Equation is that the more Circuits you add to a ( ParallelCircuit ) – The more thing you Use : Division of Installation / 314 . Dividedinto Circuits . Etc
TheLower the Total Résistance becomes . Rememberthat as the Total Résistance decreases . The Total Current increases . So ; themore things you Use . the more Current has to flow through the Cables in the PlasteredWalls .

TheInverse of the Total Résistance of the Circuit . ( Effective Résistance ) isequal to the sum of the Inverses of the Individual Résistance .

1/Rt = 1/R[SUP]1[/SUP] + 1/R[SUP]2 [/SUP]+ R[SUP]3[/SUP]+ …. ( This one come around on 2392-10 Exam )

UsefulJunk .
OhmsLaw . may be used in a ( Parallel Circuit ) aslong as you remember that you can use the formula with EitherPartial values or with Total Values . don’t mixparts

V – Total = I total : R total .
V –Part = I part : R part .

- Thepotential drops of each circuit equals the potential rise of the source .

V[SUP]T[/SUP]= V[SUP]1[/SUP]= V[SUP]2 [/SUP]= V[SUP]3[/SUP]= …..

- The total current is Equal to the sum of thecurrent in the circuits .

I[SUP]T[/SUP]= I[SUP]1[/SUP]+ I[SUP]2[/SUP]+ I[SUP]3[/SUP]+ …..

 

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Informationfor Inspector . 2391-10 .

RequirementInformation . Regulation . 610.2 . :38:

BS-7671:2008. requires that the followinginformation shall be made available to the person or persons carrying out theInspection & Testing .

 

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2392-10: Handy in yourExams . :19:

RingFinal Circuit(s)

Statethe effect on Conductor Résistance when cablesare Connected .

Whencables are connected in Parallel the overall Résistancewill be Less than the Résistance of the conductor of the lowest value .

Theformula for Calculating Résistance of Conductor(s) in Parallelis ??

1/R[SUP]T [/SUP] =1/R[SUP]1[/SUP] + 1/R[SUP]2 [/SUP] + 1/R[SUP]3[/SUP][SUP] [/SUP]+ ….. Ω

Where( RT ) is the overall Résistance .

R[SUP]1 [/SUP], R[SUP]2[/SUP][SUP] [/SUP], R[SUP]3[/SUP][SUP] [/SUP], Etc. are the Individual Résistancevalue of each conductor for as many conductors that are Connected in Parallel

Example:

Threeconductors of Résistance ( 1Ω , 2Ω ,& 4Ω ) are connected in Parallel . Calculating the total overall Résistance .

1/R[SUP]T [/SUP] = 1/R[SUP]1[/SUP] + 1/R[SUP]2 [/SUP] + 1/R[SUP]3 [/SUP][SUP] [/SUP]

1/R[SUP]T[/SUP][SUP] [/SUP] = 1/1 + 1/2 + 1/4 .

1/R[SUP]T [/SUP] = 1 + 0.5 + 0.25

1/R[SUP]T [/SUP] = 1.75Ω ( 1 ÷ 1.75Ω = 0.57Ω )

1/R[SUP]T[/SUP][SUP] [/SUP] = 0.57Ω