***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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542.2. Earth Electrode(s)

542.2.4. The type & embedded “ ► DEPTH ◄ “ of an Earth Electrode shall be such that soil drying & freezing will NOT increase its résistanceabove the required value .

 

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UsefulJunk .

Earthing Clamps . & Labelsto ( BS-951 ) must always be used .

Possibilityof corrosion the clamps should be of the ( Blue Type) Larger sizes of conductors are used then the ( GreenType ) more suitable .
( Red Clamps ) are for used in ( Dry Conditions )

( Blue Type ) & ( GreenType ) can be used as these are suitable for Non- corrosive as well as Corrosive Conditions.

 

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2392-10: Initial Verification .

Onthe completion of an Installation . it is aRequirement of BS-7671:2008: No 1 . That a Certificate is Issued to SHOW that the Installation is COMPLIANT .

2392-10: The Verification .
Mustbe carried “ OUT DURING “ & on COMPLETION of the WORK .

YourGain is . Initial Verification .
611.1. Inspection shall precede testing & shallnormally be done with that part of the Installation under Inspection ( DISCONNECTED ) from the ( SUPPLY )

Whatthe First Amendment . is saying . Wording .
610.5. On COMPLETION of Verification . according to Regulation 610.1. to ( 5 ) a Certificate shall be prepared .

Asan Inspector . 610.5. The Verification shall be MADE by a COMPETENT PERSON .

 

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Chapter 31 . Purposes . Supplies & Structure .

p/47. 314 ivision of Installation .

314.1. : Diving the Installation into circuit(s) so as to :-
(i) Avoid danger& minimise inconvenience in the event of a fault .
(ii) Facilitate safeTesting . Inspection & maintenance .

p/46. □ 314.2.
Separate circuits shall beprovided for parts of the Installation which needs to be separately controlled. in such a way that those circuits are not affected by a failure of othercircuits . & due account shall be taken of the consequences of theoperation of any single protective device .

p/46. □ 314.3.
The number of final circuits required . & the number of pointssupplied by any final circuit . shall be such as to facilitate compliance withthe regulations of chapter 43 for overcurrents protection . Section 537 for Isolating& Switching & Chapter 52 as regards current-carrying capacities ofconductors .

p/19. 132.3. Natureof Demand


□ changes are incorporated in Part 7 .

Section 701 : Locations containing a Bath or Shower basin .

□ Zone ( 3 ) is no longer defined .
□ Each circuit in a the Speciallocation must have ( 30mA RCD protection )
□ Supplementary bonding is NO longer requiredproviding the installation has main bonding in accordance with Chapter 41 .

This section now allows socket-outlets ( other than SELV &shaver supply units to BS-EN 61558-2-5 ) to be installed in locationscontaining a Bathor Shower ( 3m ) horizontally beyond the boundary of Zone 1 .

 

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“ Résistance “ -&-s 2392-10 . will come Up . Q/As

ofan Object is affected by :- :banghead:

□ Length / Résistance is directly proportionalto ( Length) Two materials of ( Equal Length ) & Cross-sectional area joined together ( Doubling Résistance )

□ Area /Two materials of ( Equal Length ) & the same ( Cross-sectional area ) joined side by side will ( Double the Cross-sectional area& Halve Résistance ) Résistance & area are Inversely Proportional .

 

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“ Resistivity “

□ Is the Amount of Résistance in a conductor & will change according to (Material ) ( Size ) & ( Distance ) the current has tomove in the Object . ( Cable )

“ Temperature “

□ when temperaturefluctuates . This affects Resistivity . ( Most Conductors)
( Most Conductors ) have increased résistance with increased temperature.

Carbon is the Exception . résistancedecreases with Temperature .

 

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“ Star Connections“

□ are usedfor an ( UnbalancedLoad ) & are a Neutral connection with an ( Untapped Earth )

“ Delta Connections “ □ are for a ( BalancedLoad )

 

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( Vd ) - Voltage drops . because the ( Reissuance) of the conductor becomes ( Greater withthe Length of the Cable )

p/304. Appendix 4 of . BS7671:2008. No 1 . gives a table of values for Cable voltagedrop in ( millivolts . per ampere . per . metre . ( mV /A / m )

Calculation’s )- This is multiplied by the circuit’s designcurrent ( Ib) & the Length of the cable inMetres ( L ) & divided by ( 1000) to give the Total Voltage Drop for aCircuit .

Voltage drop . is calculated using the following Formula . ( Voltage drop - Vd. = mV / A / m x ( Ib ) x ( L ) 1000 .

 

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2392-10 : ( NameTwo Items ) Confirmed at the same timeare ( Polarity) & the ( R[SUP]1[/SUP]+ R[SUP]2 [/SUP] ) valueof the circuit . ( T ) Q/As .-&-s .

 

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“ Client ” is the person who ordered the work & will. at the end pay the bill . 2392-10 .


Certification& Reporting . ( T ) -&-s . Q/As

□ TheSingle signatory form is used when the Design. Installation & Inspection & Testing is the responsibilityof the same person .

□ TheMultiple signatory form is used when the Design . Installation & Inspection& Testing is the responsibility of different persons .

(ix) – p/389 . When making out& signing a form on behalf of a company or other business entity . ( Individuals ) should ( State ) for whom they are acting .

 

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UsefulJunk .

Reason. Lighting .

“ Choke “ producesa ( High Voltage) when it is ( Open Circuited UnderLoad ) This high voltage causesthe ( Tubeto Strike ) or ( Switch On ) The choke also limits the Current to a ( Predetermined Value)

 

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I would Like to “ SAY “

For allthe Unsung Hero’s ( Members / Mods ) . That give up there time Freely to supportthis Forum . &keep it running without Questioning its Principles’

HAPPYNEW YEAR . Old Amber :17:

 

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UsefulJunk .

The( Light ) emitted by Mercury Gas Discharge . :13:

Whichis mainly ( Ultraviolet ) is converted to (White Light ) when it strikes the Phosphor Coating .

 

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As. Earthing & Bonding is Two different Words .

p/23. Bonding Conductor . A protective conductor providing equipotentialbonding .

Bonding :- Thelinking together of the Exposed or Extraneous metal parts of an ElectricalInstallation .

 

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UsefulJunk

CFLs ) Compact Fluoresent lamps . are miniature fluorescent lamps designed to replaceordinary ( GLS lamps )