***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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PowerCables : 2392-10 : Insulation Résistance

Whentesting Cables . ( Fault Finding ) it is Usuallybest to disconnect at Both Ends in Order to Test the Cable by itself .

 

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UsefulJunk . ( IR )

Formany years One – Megohm has been Widelyused as a fair allowable lower limit for Insulation Résistance of OrdinaryIndustrial Electrical Equipment
Ratedup to ( 1000 Volts ) PS – Wording Above 500V - 1000V

Regulation. Table 61 – p/158 . Will Reinforce this Matter .

 

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Apprentices> When a Measurement of ( PFC ) is taken as Close to the Supply Intake asPossible . ( Meaning !! At the Origin )

Apprentices> The 5 xtimes test must Only be carried out on RCDs with trip ratings ( I∆n ) up to 30mA -&-sQ/As ( Or less 30mA )

Apprentices> Maximum ( Zs ) What is the Measured value of ( Zs ) for anAltered Circuit ? A ) That it is Lowerthan the Maximum Permitted Value .

Designing: Supply Characteristics .
Natureof Supply Parameters [ This can be gained by Enquiry or Measurement ]

U )-Is Line to Line orLine .
Uo)- is Lineto Earth

Symbolsused in the Regulation . p/36 )- U . Voltage betweenLines . ( V )
Uo)- is Lineto Earth ( V )

 

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Electricityonly has Current when it is on the move . Yeah .

Formulafor Inductive Reactance : XL = 2πƒL

Thereare 4-factors thatdetermine the Résistance of a material :

1)Type of material :
Therésistance of various types of materials are different . for instance . gold isa better conductor of electricity than copper . & therefore has lessrésistance .

2)Length :
Therésistance of a material is directly proportional to it’s length . The longerthe material is . the more résistance it has . This is because the electronsmust flow through more material . & therefore meets more friction over theentire distance .

3)Cross-Sectional Area :
Therésistance of a material is inversely proportional to the cross sectional areaof the material . This means that the thicker the substance is across . thelower the résistance .
Thisis because the larger the cross sectional area is . the less friction there isover a given length [ picture in your mind . if you will . that a fire hosewill pass more water than a garden hose . because the wider the pipe . the lessrésistance it has ]

4)Temperature :
Invarious types of materials . résistance can vary inversely or directly with thetemperature . This is because of the chemical properties of the material . incarbon . for instance . the résistance decreases as the temperature rises . Sowe say it varies inversely . in copper . however . the opposite is true . withthe rise in temperature . we have a rise in the résistance .

* So not only can résistancechange with heat . but causes heat as well .

 

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Regulation705.512.2. External Influences :

( Agricultural & HorticulturalPremises)

Callsfor all equipment to have a degree of Ingress Protection of at least ( IP44 ) for protection against water splashing from any direction .
Wheremore Onerous Environmental Conditions Apply ?? Higher degree of IngressProtection will be required .

Compliance: Regulation 705.512.2. )- Where equipment of ( IP44) rating is NOT available . it shall be placedin an EnclosureComplyingwith ( IP44 ) ◄◄

IPX5)- Protection against Water Jets from anydirection ( Note : Under stated conditions )
IPX6)- Protection against Powerful Water Jets fromany direction
IPX7)- Protection against the effects of TemporaryImmersion in Water .
IPX8)- Protection against the effects of Continuous Immersionin Water .

arty:

 

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Apprentices& 2392-10 )- Please take the Time to Read
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This Test is Conducted on Domestic Installations .

I do this Test First . Why ??To make sure that I have a Earth returning back to Transformer Windings . External
BeforeI connect up My Earthing to the Consumer Unit.

TestSequence & Descriptions .

Thefollowing Test(s) are carried out with the SupplySwitchedOFF
ExternalEarth Fault Loop Impedance . ( Ze )

TheReason behind this Method )- To establish that a good Earth Exists at the Installation in Order for theremaining Test(s) to go ahead.
ProspectiveFault Current . ( PFC )

612.11.)- Protective EarthFault Current shall be Measured .
Bydoing this Test you have to Remove (Disconnect the Main Protective Bonding Conductor ) Earth – from the ( MET ) in the Consumer Unit . ( MET – MainEarthing Terminal)

TheReason behind this Method )- You are Removing Parallel Earth Paths . ◄◄◄◄
ByTesting the Line & Earth. You have a straight path to back to the Transformer Windings .

(Ze ) Measured at the Supply Position .

Onelead on ( The Disconnect the Main Protective BondingConductor ) Earth
&the Other Lead on ( At the Top of Main Switch ) Line

Younow have a Closed Circuit . ( Protective Earth Fault Current shall be Measured )

Itis one off the Easiest of all Test(s)


Line & Earth cable Only which has been Removed from ( MET ) Simple -&-s will pick your Brains on this ◄ 2392-10

-&-s)- The following Test(s) are carried out with the SupplySwitchedOFF ◄

Apprentices( What is Ze I hear you Say ??? )
Symbolsused in the Regulation . p/36 .
Thatpart of the Earth Fault Loop Impedance whichis External to the Installation ( Ωs )

 

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Apprentices: Basics
Rememberthat the : 17[SUP]th[/SUP] Edition – is British Standard :iagree:

Meaning)- ( R1 +R2 ) …. Line / R1

Meaning)- ( R1 + R2) …. CPC / R2

Putthe two together . You have ( Line / CPC ) ↔ ( Line - R1 + CPC - R2 )

Inany Exam . The Regulations will get you out of Trouble .

Toconfirm This .

Symbolsused in the Regulations p/36
( R1 ) – Résistance of the Line Conductorof a Distribution or Final Circuit (Unit Ω )
TheRegulations are pointing you to . Appx 4 – Schedule of Test Results .

Symbolsused in the Regulations p/36
( R2 ) – Résistance of the CircuitProtective Conductor→( CPC )of a Distribution or Final Circuit ( Unit Ω )
TheRegulations are pointing you to . Appx 4 – Schedule of Test Results .

(Ze ) External to the Installation p/36
Meaning )- Outside of theBuilding → Ze ] ↔ [ Zs Inside of Building.

(Ze ) You are checking that you have agood Earth from the Transformers Winding
(Zs ) You are checking That your Installationis Earthed →(Zs ) 612.9 – The Earth Fault Loop Impedance . is required to be determined forthe furthest point of each circuit

-&-s You will be asked the Qs ) Formula Calculating Earth Loop Impedance . itwill be the Option of 4 Qs ) mixed up .
( Zs = Ze + R1 + R2) ◄◄ This Qs is the start of Testing Calculation(s) for 2392-10

The colour has been added for Clarity

 

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ApprenticesBasics
LearningCurve

Regulation(s)p/333

( EIC ) Electrical Installation Certificate

Weare looking under ( Main Protective Conductors )

EarthingConductor : - Material( Copper ) C.S.A ( 10mm[SUP]2[/SUP] ) … Connection Verified Tick inbox
MainProtective Bonding Conductors : - Material (Copper ) C.S.A ( 16mm[SUP]2[/SUP] ) … Connection Verified Tick inbox

Youare Confirming )- To incoming Water & / or Gas service … ConnectionVerified Tick inbox

TheEarthing is very Important in any Installation/ or Jobs

Pointto Note : Please mark your Earthing in ConsumerUnit ?? Gas / Water ( White InsulatingTape . Why ?? if you have to come backfor any Reason you can Indentify for Testing reason . Testing comes under Common Sense . Yeah

Remember that the Certificationis you Proof in a court of Law i) Your complied with British Standards . ii)As a Competent Person . Tester .
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Testing. Yes this will come up on 2392-10 -&-s Q/As

Initial Verification – New Installation ( Certificate )
Regulation632.4.
All)- defects or omissions revealed during Inspection & Testing of theInstallation work covered by the ( Certificate ) shallbe made good before the Certificate is issued

PlainEnglish : The regulation(s) are telling you to Cover you But .
Electricians’are not Perfect 99.9% . mistakes can bemade accidently . The Reason for Testingin Order from the Regulation(s) is that every test has a reason(s) ??

TheRegulation(s) prescribed Tests . Etc

612.2.1.Continuity of ProtectiveConductors ( Dead Test) Do we have Earthing ?? ETC .
612.2.2.Continuity of Ring Final Circuit Conductor( Dead Test ) is the Ring a Complete Loop?? ETC . Do we have reverse Polarity
612.3.2.Insulation Résistance ( Dead Test ) has the cable been damaged ?? L/N – E . Megger 1552 two leads .

500V≥ 1.0MΩ ( Mains ) 2 x 230V = 460 / 500V ( your fire up doublethe Voltage ) Testing the Cable only
SELV: = 50V .A.C. = 250V D.C. ≥ 0.5MΩ
(They are only three Qs on this matter ( Table 61 – p/158 – ( 250V ≥ 0.5MΩ ) ( 500V ≥ 1.0MΩ ) ( above 500V – 1000 ≥ 1.0MΩ )
Look at the Wording . SELV / (250V ≥ 0.5MΩ )

2392-10)- Testing Q/As -&-s Yes ◄
612.3.3.Where the circuit includes ELECTRONICE DEVICESwhich are LIKELY to INFLUENCEthe results or be DAMAGED.
Onlya MEASUREMENT between the LINE conductors connected together & the EARTHING ARRANGEMENT shall be MADE . ( L& E ) Only

Nowthe Regulations are TELLING us ????? ( CoverourButs )
NOTE 1 )- AdditionalPrecautions . such as ( DISCONNECTION ) may be NECESSARY to avoid damage to ELECTRONICEDEVICES

Nowwe can say Informative

 

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Apprentice’sBasics .

Continuityof Protective Conductors . 612.2.1.

Method 1 )- ( R1 + R2 ) Line / CPC → This also proves Polarity
Method 2)- ( Measurement of R2 → or Bonding ) R2 / Wander Lead

Point to Note )- Test Voltages & Minimum Insulation Résistance .
Table 61 – p/158 - 500V to 1000V ( Above )

613.3.1. Insulation Résistance ( Domestic Installation - 500V between Live conductor(s)where appropriate during this measurement . Line & Neutral may be connected together . L/N –E separate

 

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RingFinal Circuit ( DeadTest ) Loop Testing

Thereason behind this Test !!
RingLoop Testing ensures that any Ring Circuits wired in the Installation you havecreated are actually a ( RING CIRCUIT ) & not forming a ( Radial )
“ Figure of Eight loop “

Testing must include the relevantTests from the following Checklist ( 612. )

O.S.G.(- When a Test shows a failure to comply . The installation must be corrected .The test must then be Repeated . As must any earlier test could have beeninfluenced by the failure .

Itthen chases onto the Regulation(s) 612.1.
TheTests of regulation(s) 612.2. to 612.13. where relevant . Shall be carried out &the results compared with relevant Criteria .
TheRegulation are telling us in Order . each test has its Reason

Apprentices. O.S.G. p/80 – 2392-10 will use this system

Continuityof Ring Final Circuit Conductors . p/80 – A Three-step Test is required to Verify the Continuity of the Line . Neutral & Protective conductors & the correct wiring ofthe Ring Final Circuit . Etc

Step1 )- p/81 / End to End ( MeasuredSeparately ) L/N/CPC
Step2 )- p/81
Step3 )- p/82

Youwill see ?? ( Little r[SUP]1[/SUP]+ r[SUP]2[/SUP] ) don’t get confused with ( R1 + R2 )

 

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2392-10: NEW
Purposeof Initial Verification .

InitialVerification . in the context of Regulation 610.1.is intended to confirm that the Installation complies with the Design & hasbeen Designed & constructed in Accordance .
610.1. ) 611.2. ) 612.1. )

 

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2392-10: ( T )
Certificates

Appendix6 of BS-7671 contains Three model forms for the Initial Certification of a ( NEW ) Installation or for an Alteration or Addition toan existing installation as follows.

Ambringing you to the Point )- Single Signature ( ElectricalInstallation Certificate)- That is you 2392-10
WhereDesign . Construction . Inspection & Testing are the RESPONSIBLY of ONE PERSON )- That is you 2392-10

ACertificate with a Single Signature MAY REPLACEthe MULTIPLE SIGNATURE form ◄◄◄
:iagree:

 

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2392-10: This will come up -&-s
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Regulationp/339 . ( PIR)

Periodic Inspection Report .
Regulations )- row 5 . The “ Extent& Limitations “ box should fullyIndentify the elements of the Installation that are covered by the report &those that are not . This aspect having been agreed with the CLIENT & other interested parties before the Inspection & Testingis CARRIED OUT .

Tester. GN-3 p/19 .
Scope)- it is essential that the Inspector & the Person ordering the Inspectionknown the “ Extent “ of the Installation to beInspected & any Criteria regarding the “ Limit“ of the Inspection . ( BOTH should be AGREED & RECORDEDon the CERTIFICATE )

Regulation)- Schedule of Inspections P/340
Bottomof Page ??

NOTES : ( LIM ) ◄◄ -&-s/ Big time . PS trip up Q .
ToIndicate that . exceptionally . a “ LIMITATION“ agreed with the person ordering the work preventedthe Inspection being carried out ( Applicable for a PeriodicInspection Only )

 

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2392-10: ( ADS )
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TestingRCDs
Wherean RCD has a rated value of ( I∆n ) not exceeding ( 30mA ) & is used toprovide Additional Protection to BASIC PROTECTION the operating time of the device mustnot exceed ( 40mS ) when subject to a Test Current of ( 5 x I∆n )