***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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“ This is a Live Test “ .
415.1.1. –. Additional protection : RCDs

It only works if the RCD is “ Energised “
Regulation RCD effectiveness of any testfacility incorporated in the device
To Ensure . The test buttonshould operated at intervals of not greater than 3 months . BS- 514.12.2. p/118..

H&S . Legislation .
The Electricity at Work Regulations 1989 . specificallydeal with Electrical “ Systems “ Regulation 4 .

i) All “ Systems“ shall at all times be of suchconstruction as to prevent . so far is reasonablypracticable . Danger .
ii) As may benecessary to prevent “ Danger “ all systems shallbe maintained . sofar prevent . so far as is reasonablypracticable . Danger .
iii) Every work activity . including ( Operation ) use & maintenance of a sytem &work near a system . shall be carried out in such a manner as not to give rise. so far is reasonablypracticable . Danger .
iv) Any equipment providedunder these Regulations for the purpose of ( ProtectingPerson(s) at work on or near Electrical Equipment shall be suitable for the use for which
it is provided . etc .

415.1.2. An RCD is not used as the solemeans of protection & does not obviate the need to apply one of theprotective measures specified in section 411 to 414 .
- AnRCD is not used as the sole means of protection against Exposed live conductors.

Wiring regulation 17[SUP]th[/SUP] Edition – 2011
Which . amongst other requirements .specifies therequired methods for safe Fusing & Earthing . 415.1.2. The single most important precautionagainst Electric Shock is a properly constituted Earthing System supported by ( Fuses or MCBs ). To correctlydisconnect the supply in case of Overcurrent or Fault to Earth .

□ For “Portable Units “ the Test Button shouldbe operated before every use at a new site to ensure that it isFunctioning .
You know the outcome . Any device failing to Trip must be removed from service .

 

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612.13.: Functional testing . 2392-10 . last test .
i) Where ( ► Faultprotection ) & / or ( ►Additional protection) is to be provided by an RCD .
ii) The effectiveness of any test facility incorporatedin the device shall be verified .

 

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Determining the Protective DeviceCharacteristics’ . “ MCB “ p/38

Main formula .

( Iz > In > = Ib )
433.1.1.:
Ib ) –Design current of circuit ( A ) Load to be connected tothe circuit . :
Table 41.3.
In ) – Ratedcurrent or current setting of protective device ( A ) .
433.1.1.
Iz ) –Current-carrying capacity of a cable for continuous service under theparticular installation conditions concerned ( A )

This means that in every circuit at all times thecurrent carrying capacity of the cables must be ( Higher ) than the ( Highest ) possible load current .
The ( Protective Device ) rating must be ( Higher ) thanthe ( Load Current ) but ( Lower ) than the maximum current carrying capacity ofthe ( Cable ) installed

-&-s 2392-10: RCDs “ MUST “be used in conjunction with an “ Overload ProtectionDevice “ such as MCB .
-&-s 2392-10: RCD . Double-poleswitching types are preferred to ensure full isolation should a fault occur .

 

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RCD: Hazards .

RCDs– don’t offer protection against current Overloads .
RCDs– will NOT protect against a socket outlet being wired with its Line &Neutral terminals the wrong way round .
RCDs– will NOT protect against the overheating that results when conductors are NOTproperly screwed into their terminals
RCDs– will NOT protect against Line & Neutral shocks . because the current inthe Line & Neutral is balanced . so if you touch Line & Neutralconductors at the same time . ( bothterminals of a light fitting ) you maystill get a shock .

 

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2392-10 : Visual Inspection . 611.1. to 611.3.
“ Inspection “ shall precede testing & shall normally be donewith that part of the Installation under Inspection ( Disconnectedfrom the Supply )

 

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Useful Junk .
Earth Fault LoopImpedance Test . cannot be conducted ( Before )an Installation is connected to the ( Supply ). -&-s

 

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Continuity of Conductors in Ring Final Circuit . 612.2.2.
Purpose of this test is to verify that the Ring FinalCircuit . are
Correctly wired & connected .
Continuous .
-&-s. Not interconnected / Bridged

 

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Earth Electrode Résistance .612.7.

Where the Earthing System incorporates an EarthElectrode as part of the Installation , The Electrode résistance to Earth shallbe ( Measured )

The Earth Electrode . where used . is the means ofmaking contact with ( General Mass of Earth ) Thus it must be ( Tested) to ensure that good contact is made .
Your main consideration here 2392-10 : To ensure thatthe Electrode résistance . is ( NOT HIGH ) thatthe voltage from Earthed Metalwork to Earth ( Exceed50V ) ◄

Where an RCD . is used This means that the result ofmultiplying the RCD operating current ( in Amperes ) by the Electrode résistance( in Ohms ) does NOT Exceed 50V ◄
If a ( 30mA /RCD ) is used . This allows a maximum Electrode résistance of ( 16667*Ω ) althoughit is recommended ( Table 41.5. – Max Earth Fault LoopImpedance ( Zs )

Earth Electrode résistance should NEVER be GREATER than (200Ω )

 

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2392-10: An Inspection and Test which is carried out on a NEWInstallation to PROVE Compliance is called , Initial Verification ,

 

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2392-10:

Whena New Installation has been Completed , it must be Inspected and Tested toEnsure that it is” SAFE “ to use ,
ThisProcess is known as the Initial Verification ,Regs 610.1 for Safety reasons , the Inspection process must precede Testing ,

 

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Please take the TIME to READ this MATTER . 2391-10 / 2392-10 ◄◄ :13:

This Forum can ONLY give YOU GUIDANCE . ◄◄

What is ( Time ) Money .


Firstly. We are ( All) guilty of NOT reading theQuestions / Rightly. 2391-10 . C&G ?? . :blush5:


C&G ?? Identifythe most suitable test instrument for a set of circumstances C&G ?? . GN-3 . ( Incorrect Instrument Names being Used in Exams ) 17[SUP]th[/SUP] Edition& 2011 .


☼ p/83 . GN-3 . Insulation RésistanceOhmmeters’ .
the instrument used should be capable of developing the( Test ) voltage requires across the ( Load )

[ Instrument conformingto BS-EN-61557-2 ] ◄◄◄

☼ p/83 . GN-3 . Earth Fault Loop Impedance Testers
These instruments operate by ( Circulating ) a currentfrom the Line conductor into the Protective Earth . This will raise thepotential of the Protective Earth System .

For circuits rated to ( 50A ) a Line-Earth loop testerwith a resolution of ( 0.01Ω ) should be adequate . in general . suchinstruments can be relied upon to be accurate down to values of around ( 0.2Ω )

Instruments conforming to BS-EN-61557-3 . will fulfilthe above requirements . ◄◄◄

☼ p/84 . GN-3 . Earth Electrode RésistanceTesters .
this may be a ( Four terminalinstrument ) OR ( Three terminal One ) where a combined lead to the ( Earth Electrode ) would not have a significant résistancecompared with the ( Electrode Résistance ) sothat the résistance of the test leads & temporary spike résistance ( Can be eliminated from the Test Result )

-&-s ?? .Please NOTE (- “ Wording Used “ . ◄◄
It may be HELPFUL to NOTE thatInstrument complying with ( BS-EN-61557-5 ) . incorporatethis facility . ◄◄

 

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☼ p/84 . GN-3 . -&-s ?? . PleaseNOTE (- “ Wording Used “ . ◄◄
Phase Rotation Instrument . BS-EN-61557-7. ◄◄ . gives the requirements for measuring equipmentfor testing the ( Phase Sequence in Three-phase distribution systems .
[ Whetherindication is given by . Mechanical . Visual . & /or AudibleMeans . ]

☼ p/84 . GN-3 . -&-s ?? . PleaseNOTE (- “ Wording Used “ . ◄◄
RCD Testers .
The test instrument should be capable of applying thefull range of test current to an ( In-service ) accuracy as given in (BS-EN-61557-6 ) ◄◄
Now -&-s (- Wording Only . 2392-10 Exams . To CHECK - RCD operation & to minimise ( Danger ) during the test . The test current should beApplied ( For No Longer Than2 Seconds ) 2392-10 . This only Appliesto RCD Only . ◄◄◄◄◄◄

☼ 2392-10 . The instrument used for ( Low – Résistance Tests) 612.2.1. No-load voltage between 4V &24V . & a short– circuit current NOT less than 200mA .
Instrument to ( BS-EN-61557- 4 ) will meet the above requirements . ◄◄◄◄◄◄

☼ p/81 –GN-3 : Instrument Standard .
The ( Basic ) instrumentstandard is ( BS-EN-61557 ) Electrical Safety in Low-Voltage Distribution Systems. Up to 1000V . a.c. & 1500V . d.c. Equipment for Testing .Measuring or Monitoringof Protective Measures . ◄◄◄◄◄◄

NOTE (-. This Standard includes performance requirements & requires ( Compliance with BS-EN-61010 )

ISBN-978-086341-857-0 . GN-3

 

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Amendment 2011 .

□ Electrical Installation Condition Report .

Electrical Installation Condition Report . ( EICR ) from Appendix 6 of BS-7671 . is for use when carrying out ( Routine ►► PeriodicInspection & Testing ) of an Existing domestic& similar installation . with up to ( 100A ) ( Single – phase ) or ( Three-phase) supply .
►► It isNOT use when ( Alterations or Additions are Made)

A Generic Scheduleof Test Results ( 4 ) & aCondition Report Inspection Schedule ( 7 ) shouldaccompany the Electrical Installation Condition Report ( 6 )

( 6 ) The ElectricalInstallation Condition Report . ( EICR ) to be used for Domestic & SimilarInstallations with ( 100A ) Single – phase ) or ( Three-phase ) supply
( 4 ) Generic Schedule of Test Results .
( 7 ) Condition Report Inspection Schedule . ( forDomestic & Similar Premises with up to ( 100A ) supply .

 

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The ( Forms ) are Numbered .

1 ) . Electrical Installation Certificate . Please Note : (Single – Signature )
2 ) . Electrical Installation Certificate .
3 ) . Scheduleof Inspections . Please Note : ( for NEW Installation Work Only )
4 ) . GenericSchedule of Test Results .
5 ) . Minor ElectricalInstallation Work Certificate .
6 ) . ElectricalInstallation Condition Report .
7 ) . ConditionReport Inspection Schedule . Please Note : ( forDomestic & Similar Premises with up to ( 100A) supply .

( 1 & 4 ) are designed for use when ( Inspecting & Testing ) a New Installation . or an Alteration orAddition to an ( Exceeding Installation ) forms comprise the following .

1 ) . Short –form of . Electrical Installation Certificate . PleaseNote : ( to be used when oneperson is responsible for the Design . Construction . Inspection & Testing. of an Installation ) OR .
2 ) . Electrical Installation Certificate . ( Standard from Appendix 6 of BS-7671 )
3 ) . Scheduleof Inspections . Please Note : ( foe NewInstallation Work ONLY )
4 ) . Generic Schedule of Test Results . .

 

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-&-s . State the ( TWO ) different types of Inspection & Testing . may require

“ InitialVerification “ … ( Initial Verification & Inspection )
“ Periodic Inspection & Testing “ … ( ElectricalInstallation Condition Report )