***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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Certification & “ Reporting “ :aureola:

Fundamentally . Two typesof form are recognised by BS-7671 . Certificates & Reports .

□ Certificates are issuedfor New Installation Work .
□ Reports are Issued forInspections of Existing Installations .

Certification

Two types of Certificatefor New Work recognised by BS-7671 :
□ ElectricalInstallation Certificate .
□ Minor ElectricalInstallation Work Certificate .

● ElectricalInstallation Certificate . is intended to be is used where moresignificant Installation Work is undertaken .
● Minor Electrical Installation Work Certificate . is intended to be issuedfor an Addition or Alteration to an existing circuit .

 

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□ Lighting Protection System ( LPS )

LightingProtection System . Protects thestructure NOT the Equipment .

□ Surge Protective Device ( SPD ) Basic

Divert Surge Currents & limit Over-Voltages . & Equipment

 

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ApprovedDocument Part – P . :carols:

ElectricalSafety in Dwellings . P1 .

Kitchen–

isdefined in the Building Regulations as a Room or Part of a Room which contains aSink & Food preparation facilities .

“ As a guide only “ inOpen plan areas the zone of a Kitchen may be considered to extended from theedge of the Sink to a distance of ( 3m ) or to anearer dividing wall .


□ In large bathrooms . The locating a Bath or Shower isdefined by the ( Walls of theBathroom )

Just a Reminder p/15 . 2392-10

B/R . 2008

The BuildingRegulations ( Regulation 4 (2)) require that on (Completion of Work ) in an existing building. The building should be NO WORSE in terms of the level of compliance with the otherApplicable Parts of Schedule 1 . to the Building Regulations . including Parts . A. B . C . E . F . L. & M .

P/15.
PartA . ( Structure ) depth of chases in walls .& size of holes & notches in floor & roof joists .

PartB . ( FireSafety ) fire safety of certain electricalinstallations . PROVISION of fire alarm & fire detection systems . fire résistance ofpenetrations through floors & walls .

PartM . ( Access to& use of buildings ) heights of switches . socket outlets &other equipment .


Just a Reminder 2392-10. :christmaswreath:

Theprimary RESPONSIBILITY for ACHIEVING COMPLIANCE with the Building Regulations rests with the PERSON carrying out the Building Work .

 

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Appendix 6 . ( Informative ) :gettree:

Certification & Reporting. p/389

(i) The ElectricalInstallation Certificate required by Part 6 should be made out & signed or otherwise authenticated by a ( Competent Persons or Person(s) in respect ofthe design . construction . inspection & testing of the work .

(ii) The Minor Works requiredby Part 6 should be made out &signed or otherwise authenticated by a (Competent Persons or Person(s) in respect of the design . construction . inspection& testing of the minor work .

(iii) The ElectricalInstallation Condition Report requiredby Part 6 should be made out &signed or otherwise authenticated by a (Competent Persons ) in respect of the inspection & testing of anInstallation . .

(iv)( Competent Persons ) will . as appropriate to theirfunction under (i) (ii) & (iii) above . have a sound knowledge & experience relevantto the nature of the work undertaken & to the technical standards set downin these Regulations . be fully versed in the ( Inspection & Testing ) procedurescontai9ned in these Regulations & ( Employ Adequate Testing Equipment )

(v)The Electrical Installation Certificate will ( Indicate ) the responsibility for design . construction .inspection & testing . whether in relation to ( NEW WORK ) or further work on an ( EXISITING INSTALLATION ) .

2392-10 (- -&-s 2011 :17:

Where design . construction. inspection & testing are the responsibility of ( ONE PERSON ) a Certificate with a ( SINGLE-SIGNATURE DECLARATION ) in the form shown below ( MAY REPLACE ) the ( MULTIPLE SIGNATURES )

 

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Protection Against Overcurrent . Chapter 43 . p/79

430.3. General Requirement. (T )

A protective device shall be provided to break any ( Overcurrent in theCircuit Conductors ) before such a current could cause a ( DANGER ) due to ( THERMAL ) or MACHANICAL effects detrimental to ( INSULATION ) connections . joints . terminations orthe surrounding of the Conductors .

The protection against overload current & the protectionagainst fault current shall be co-ordinated in accordance with section 435.

NOTE :- An overcurrent maybe an ( Overload current ) or a ( Fault current ) :icon_bs:

 

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:17: 2392-10. ( T)

Inspection & Testing section of an Electrical InstallationCertificates must be signed only by a competent person or person(s)

Regulation : 631.4 - p/196 .

□ ElectricalInstallation Certificates . Electrical Installation Condition Reports &Minor Electrical Installation Works Certificates shall be compiled & signedor otherwise authenticated by a competent person or persons .

In this context . “ Competent “ means having adequate knowledge &experience of the type of work being Inspected & Tested in order to be able to “ Verify “ so far as is reasonably practicable . whetheror not the work meets . the requirements of BS-7671:2008 - First Amendment . 2011 .

□ For Alterations & Additions . it needs to be “ Verified“ that the work complies withBS-7671:2008 - First Amendment . 2011 . &does not impair the safety of the existing installation . Regulation - 633.1. - p/196. it also needs to be confirmed that theEarthing & Bonding arrangements upon which the new work relies for safetyare adequate Regulation – 132.16 . Any defects found in the existing installation. found in the existing installation unrelated to the work being certified .must be recorded on the certificate . Regulation – 633.2. – p/196 .

□ The person(s) responsible for Inspection & Testing thework are responsible for comparing the results with the relevant criteria .Regulations - 612.1. – p/190 . to confirm that the work Inspected &Tested meets the requirements of BS-7671:2008 - First Amendment . 2011 . before signing for Inspection &Testing element of the work on the certificate. for example ! . it needs to beconfirmed that the limiting values of ((Zs )) have not been exceeded .

□ if any Test indicates a failure to comply . that test . theresults of which may have been influenced by the circumstances that caused the failure. need to be repeated after the fault has beenrectified . Regulation - 612.1. – p/190 . Defects or Omissions revealed during the Inspection& Testing must be made good before the work is put into service &before the certificate is signed & issued . Regulation - 632.4. p/196.

□ The person(s) responsible for Inspection & Testing mustcompile the Schedule of Inspections & the Schedule of test results . forissue as part of the certificate to the person ordering the work . Regulation - 631.1. p/195 .

Earthing & Bonding arrangements :carols:

Earthing (- Connection of the exposed-conductive-parts ofan installation to the Main Earthing Terminal of that installation . p/27
Bonding (- Bonding conductor . Aprotective conductor providing Equipotential bonding . p/23

2392-10.

Part P of the Building Regulations for England& Wales. :carolers:

Domestic Electrical Installation Work . That is notifiable underPart P of the Building Regulationsfor England& Wales. Only the person(s) responsible for the ( CONSTRUCTION ) of the ( WORK ) are (LEGALLY ) entitle to Self-certify that the Electrical Work Complieswith the relevant requirements of the BuildingRegulations

 

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Mounting Heights of Electrical Equipment in Dwellings . :santa5:

Regulation 553.1.6. p/174.

Requires that a wall mounted socket-outlet is sufficient heightabove the floor or any working surface to minimize the risk of mechanicaldamage to the socket-outlet or to an associated plug & flexible cord duringinsertion . use or withdrawal of the plug .

553.1.6.
A socket-outleton a wall or similar structure shall bemounted at a height above the floor or any working surface to minimize the riskof mechanical damage to the socket-outlet or to an associated plug & itsflexible cable which might be caused during insertion . Use or withdrawal ofthe plug .

 

[oldAL]

are you really allowed to reproduce copyrighted material in such a manner?

 

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Automatic Disconnection of Supply. ( ADS)
A requirementof the regulations is that in the event of a fault occurring of negligibleimpedance between Live conductors ( Being / Neutral) or Line conductors & Earth .
Supplyis interrupted within the times stated in Table 41.1. BS-7671:2011.

TT. – Uo / 230V . 0.2 for any circuits rated ( Under ) ≤ 32A) & ( 1s ) for any circuit ( Over ) ≥ 32A )
DisconnectionTime could be Met – by the Use of an RCD .

TTsystem – maximum EFLI - ( Zs ) Ω

AnEarth Electrode value of greater than ( 200Ω ) is considered by some to beUnstable . Other use a figure of ( 100Ω)
Singlevertical rod Electrodes . “ Depth “ is an Important Factor & a ( 2.4m deep ) Electrode with Initial Résistance of . say ( 300Ω) will be more stable than a shallow (1.2Ω ) rod with an initial résistance of. say ( 100Ω ) Thus the effects of freezing & drying out can be all buteliminated in the UKby installing ( 2.4mDeep Electrodes’ )

Asthe BS-7671:2011. Rightly reminds us . For Non-delay RCDs to BS-EN 61008-1& BS-EN 61009-1

Table 41.5. are Obtained by the use of “ Ohm’sLaw “

Calculation is given in Regulation 411.5.3. ( R[SUB][FONT="Times New (W1)"]A [/SUB]x IΔn ≤ 50V ) [/FONT]

R[SUB][FONT="Times New (W1)"]A [/SUB] ) is the résistance of the Earth Electrode &the Protective conductor ( Zs ) can beused in place of ( R[SUB][FONT="Times New (W1)"]A [/FONT][/SUB] ) ◄◄ “ WORDING “ [/FONT]
R[SUB][FONT="Times New (W1)"]A [/SUB] ) is the résistance of the Earth Electrode &the Protective conductor connecting itto the exposed-conductive-parts ( in Ohm’s ) [/FONT]
IΔn ) is the Trip current rating of the RCD .
50V ) is the Maximum permitted Touch Voltage .

Calculation )- it is Importantto remember that in most cases the trip rating of an RCD is given in ( milliamps )
Calculation )- to find the Maximum Résistance permissible fora ( 30mA RCD ) - 50/0.03 = 1666.66. Rounded up 1667Ω

 

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TT System . 411.5.

411.5..2 )- One or More of the followingtypes of protective devices shall be Use . theformer being preferred ( i ) AnRCD . ◄◄
(ii) Overcurrent Device . MCB.

NOTE 1 . An appropriate overcurrent protective device may be usedfor fault protection provided a (Suitably Low Value of Zs ) ispermanently & reliably assured .

□ Generalpurpose RCDs to BS-4293 . are Used . this is not a problem as they mustdisconnect within ( 200mS ( 0.2s ) this would satisfy Regulation 411.3.2.2.
p/53 :- 411.3.2.2. . The maximum disconnection timestated in Table 41.1 shall be applied toFinal Circuit NOT Exceeding ( Under ) ≤ 32A )

□ The requirement for BS-EN type RCDs is that they disconnect within ( 300mS ) ( 0.3s ) This disconnection time is not ( Fast Enough )to satisfy the Regulations . & their use could cause some “ Concern “

Regulation do take into Account that a ( Fault Current ) is going to be at least TWICE the TRIP rating ( 2 Δn) of a-the RCD
As a FAULT CURRENT is almost certainly going to be ( 2 x IΔn ) a BS-EN Type RCD will comply with theRequirements .

Asthe BS-7671:2011. Rightly reminds us p/295 . BS-EN type RCDs . Appendix 3 . BS-EN 61008-1& BS-EN 61009-1
Operates within the correct time ( 300mS ) at times one ( IΔn ) then it will operate at (150mS or Less at twice IΔn )

Therefore . if the RCD is satisfactory when tested at times ( Half) ( Times One ) & ( Times Five 5 xtimes for 30mA & below Only )
No further tests are required . & it can be Accepted that theRCD is Satisfactory .

p/57- Table 41.5. of BS-7671:2011 . provides maximum values of ( Zs ) which will ensure the correct operation of theRCD .

 

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Prospective Fault Current . ( PFC )

The maximum fault current which can flow between Live conductorsis called ( PSCC )
The maximum fault current which can flow between Live conductors& Earth . ( PEFC )

2392-10 (- As a Tester . You are required to determinethe value of each of these TWOCURRENT.S.

( By Measurement ) -&-s . The Highest Value must be recorded . Test Certificate “ Known as ( PFC ) -&-s

2392-10 :- InstalledEquipment in an Domestic Installation must be capable of withstanding the Maximum Fault Current ( PFC) which could flow at the point at which it is installed . for -&-s point of View . Ensuring Equipment is to the British Standardwill ensure Compliance .

Regulation s 612.11. ProspectiveFault Current .

2392-10. The prospective short-circuit current & prospectiveearth fault current shall be MEASURED . calculated ordetermined by another method , ( At The Origin , & other relevant points in the Installation .

 

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Regulation132.16 . 131.8.

Theadequacy of the Existing Installation istherefore required to be Assessed in THREE-AREA.S .

□ Existing Equipment – including that of theSupply . may have to carry Increased Load .
( it is necessary to establish that the rating& condition of all appropriate equipment within an Installation Overcurrents / MCBs )

□ Earthing & Bonding arrangements .
( Verification of the means of Earthing bydetermination of the External Earth Fault Loop Impedance ( Ze ) 313.1. ( iv )
• As a Measured value to verify that theintended means of Earthing is both present & of the expected value .
• Ascertaining that the Earthing Conductor isof Adequate Cross-sectional area .

□ Certain additional considerations .
( The ratings of cables in the Installation )

2392-10:- Upgrading of an Existing Installation. where necessary .

□When an Existing Installation is NOT adequateto support a proposed Addition or Alteration safely the work must NOT proceed .

□The client must be Advised immediately & preferably in writing .

□ The necessary upgrading work should be recommendedto the client .

□ When the client’s consent has been given . theupgrading work should be completedbefore the Addition or Alteration is put into service .

Installation.
Additionto .or upgrading of . main protective equipotentialbonding in an Installation relying on the protective measure ( ADS ) for Protection .

Whereprotection is provided by ( ADS ) Regulation 411.3.3.

610.4. p/189 .

For an Addition or Alteration to an existing installation . itshall be VERIFIED that the Addition or Alteration complies with the Regulations& does NOT impair the safety of the EXISTING INSTALLATION .

110.1.2. p/14 . ( vi ) “ SCOPE “
Addition or Alterations to installations & also parts of the existing installationaffected by an Addition or Alteration ◄◄
[ Safety of the Existing Installation ]

610.5.
The Verification shall bemade by a Competent Person .

 

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2392-10: -&-s . Q ) Circumstances which require an Initial Verification .
A) New installation(s) or Additionsor Alterations .

612.9. : Earth Fault Loop Impedance .
612.10 : Additional protection – RCDs . [ Toconduct the Test on – “ Earth Fault Loop Impedance “ before “ Additional protection “ Why ? . A faulty RCD can pose a problem . “ Shock Risk “ if the Loop Impedance is Inadequate.

UnderFault Conditions . the Earth is a Live Conductor. CPC .

CPC.Form part of an Earth Fault Loop path within an Installation .
It’s purpose is to carry any current which is caused due to anEarth Fault & forms part of the (ADS ) Important . -&-s


Any “ Article(s) “ provided by this forum in this section . assume that the Designer & Installerintend to comply fully with the requirements of the 17[SUP]th[/SUP] Edition . BS-7671:2008. No 1 . 2011

 

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SteelWire Armour used as a CPC . “ Useful Junk “ .

Table 54.7. p/162 .
Minimum cross-sectionalarea of protective conductor in relation to the cross-sectional area ofassociated Line Conductor .

Calculationto use which will give us the minimum CSA of the Steel Wire Armouring which is suitable foruse as a ( Protective Conductor )
Withoutany further calculation other than ( Zs )

2392-10: Using a ( 10mm[SUP]2[/SUP] two core ) - ( 70°C) thermoplastic .
SteelWire Armour Cable . Using the Armour forthe CPC.

Calculation– minimum CSA . of Armouring. ?
[ k[SUP]1[/SUP] / k[SUP]2[/SUP] x S ]

Table. 43.1. or 54.3.
Value ( k ) for aCopper Conductor is ( 115 )
54.3. is for theprotective conductor & that we are looking for Value ( k ) for the Line Conductor.
( Copper Conductor ) it will have the same Value ( k ) as it would have if itwere to be Used as a CPC .

p/85. Table ( 43.1. ) Values of ( k ) for CommonMaterials , for calculation of the effects of Fault Current for disconnectiontimes up to ( 5 sec )

p/161. Table ( 54.3. ) Values of ( k ) for protectiveconductor ( INCORATED ) in a ( CABLE ) or bunched withcables . where the assumed Initial Temperature is ( 70°C ) or ( Greater )

p/161. Table 54.4. Value ► ( k ) for ► ( Steel Sheath Armour ) is ► ( 51 ) Note - ►► ( 70°C ) thermoplastic.
Calculation– 115 ÷ 51 x 10mm[SUP]2[/SUP] = 22.54mm[SUP]2 [/SUP]


□ Any “ Article(s)“ provided by this forum in this section. assume that the Designer &Installer intend to comply fully with the requirements of the 17[SUP]th[/SUP] Edition . BS-7671:2008. No 1 . 2011

 

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“ Useful Junk “ Stay Focused here Chaps - 2392-10

542.2. Earth Electrode(s)

542.2.6. - An Earth Electrode shall NOT consist of aMetal Object ( Immersed in Water ) ► Q/As -&-s after 2011 . Inspector / Testing :mad2:

 

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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 )

 

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2392-10. Your Assessor . is looking for this principle .

p/25. CompetentPerson .

Aperson who possesses sufficient technical knowledge & experience for thenature of the electrical work undertaken & is able at all times to preventdanger . & where appropriate . injury . to him/herself & others .

This Definition is aligned with . the Memorandum of Guidance on the Electricity atWork Regulations 1989 – ( HS(R) 25 ) Guidance onRegulations
​

 

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BS-7671:2008. No 1 . 2011 .

411 . Protective Measure – Automatic disconnection of Supply .

Disconnection Times .
p/53. Disconnection circuit(s) & circuit(s) not covered by Table 41.1.

p/54- 411.3.2.3. TN- : 5 s maximum .
p/54- 411.3.2.4. TT- : 1 s maximum .
p/60- 411.8.3. Reduced Low-voltage system(s) . 5s maximum .
p/179- 599.10.3.3. Outdoor Lighting Installations . 5s maximum .

 

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411 – Protective Measures / Automatic disconnection of the Supply .

Fault Protection .

2392-10 . Three Components “ That is Important“
​

p/53- 411.3.1.1. ProtectiveEarthing .
411.3.1.2. Protective Equipotential Bonding .
411.3.2. Automaticdisconnection in case of a Fault .

 

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Justa Reminder .

Part 5 – Selection & Erection of Equipment .
p/169- Chapter 55 – Other Equipment .

p/172- 551. Low VoltageGenerating Sets .

551.7.2.
i) The conductors of the final circuit shall meet the following .

( Iz ≥ In + Ig )

Where :
Iz ) is the current-carrying capacity of the final circuitconductors .
In ) is the rated current of the protective device of the final circuit.
Ig ) is the rated outputcurrent of the generating set . &

ii) not be connected to afinal circuit by plug & socket . &
iii) A 30mA RCD on thefinal circuit shall disconnect all Live Conductors .
iv) The Line & Neutralconductors of the final circuit & of the generating set shall not be connected to Earth.
v) Disconnection times muststill be Met .

This regulation does not apply to an Uninterruptible Power Supply provided to supply specific items ofcurrent –using equipment within the final circuit to which it is connected .

 

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p/163- 543.2.7. Earthing Tail Requirement .

Where the protective conductor is formed bymetal conduit . trunking or ducting or the metal sheath and/or armourof a cable . the earthingterminal of each accessory shall be connected by a separate protective conductor to an earthing terminal incorporated in the associated box or other enclosure .

 

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2392-10.

Colour Coding of the Insulation ensures correct Polarity atTerminals . ( Insulating Tape ) Tail’s

 

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Sorry . Grand kids all day . can’t get my head stuck into books . :banghead:

CableSizing .

Sizingof an Electrical Load . “ Cable “

Importantthat the cable can :-

□ Operate continuouslyunder ( Full Load ) without being damaged .
□ Withstand the worst ( Short Circuit(s)Current(s) flowing through the cable .
□ Provide the load with a suitable voltage . ( Avoid excessive voltage drops )

• Ensure operation of the ( Protective Device during an Earth Fault )

Definitions . p/26.
EarthFault Current . A current resulting from a Fault of negligible impedancebetween a Line conductor & anExposed-conductive-part ( or a Protective Conductor )

Résistanceof the Protective Earthing. ( PE ) conductors mustbe low enough to permit the passage of current necessary to operate the Protective Device .

Q/. When . Earth Fault Loop Impedance should be measured .
(Using a suitable instrument ) 612.1. BS-EN 61557.

□ Installation work is completed .
□ Checking Inspection / Visual . & Testing has been carried out .
□ Supply has been applied .

 

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Thenominal voltage is 230V . The ( Maximum voltage drop ) from the “ Point of Supply“ where the Consumer Mains joints to the Installation(s) cable(s) .
“ Power “ Toany part of the Installation must NOT be more than ( 5% )

Thisis to ensure that “ Appliances will operate as intended . ( 5% ) Voltage Drop = 11.5V .
p/314- Table 4Ab –Voltage drop . ( Lighting – 3% ) - ( Power – 5% ) DNO .

(i) Low voltage installation(s) directly from a Public Low voltage …………. Etc .

Appendix. 4 of BS 7671:2008: No1 . (wiringregulations) states that 'The voltage drop between the origin of aninstallation and any load point should not be greater than the values in Table 4Ab , expressed with respect to the value of the nominal voltage of the installation'.

To help select cables that comply with the percentagevoltage drops specified above, the cable data given in Appendix4 of BS- 7671:2008: No 1 . supplies values from which the appropriate calculations can be made. Thesevalues are expressed in terms of a current of oneampere for arun of one metre .

p/130 - 525.101.
The above requirements are deemed to be satisfied if the voltagedrop between the Origin of the installation ( Usually the supply terminals )& a socket-outlet or the terminals of fixed current-using equipment doesnot exceed that stated in Appendix 4 .

P/256 . Table of Voltage Drop. 6 .
In the tables . values of voltage drop are given for a current of one ampere for a metre run . i.e. for a distance of 1m along the route taken bythe cables .

 

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RCDswork on . Current Alone .

Ifthe Outgoing current doesn’t Equal thereturning current then it should Trip .

( RCDs operateon Current . in order for current to flow youmust have a ( Potential Difference)

p/34- Residual Operating Current :- Residual Current which causes the RCDto operate under specified conditions .


□ Regulationsrequiring CPCs in lighting circuits were introduced in 1966 .

□ ElectricalExtension Leads . The longer the run ofcable . The more Résistance . mort Heat. CoP.

 

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UsefulJunk

Lighting / Lamps. every night.

16. hour / day . x 7 . day / week . x52 weeks = 5840 / hours . ( 16 x7 x 52 = 5840 h/s )

3. hour / day . x 5 . day / week . x 20 weeks = 300 / hours . ( 3 x 5x 20 = 300 h/s )