Re-take - Useful Information for 2394 :

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Useful-junk .
P/29 , Leakage-current : Electric-current in anunwanted-conductive-path , under normal-operating-conditions .
Touchcurrent :- also known, as earth-leakage-current must be withinspecified limits for its Class. :aureola:
Class I equipment, the earth-leakage-current is thecurrent that flows in the earth supply conductor during normal operation of theequipment.
Class II equipment, leakage is measured to earth fromaccessible conductive-parts of the enclosure

 

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2008: GN-3 ,States : if test an installation as a whole
Insulation-résistance to earth.
" Although aninsulation-résistance-value of not lessthan 1.0 MΩ complies with the Regulations, where an insulation resistance ofless than 2MΩ is recorded the possibility of a latent defect exists. ( In these circumstances, each circuit should be tested separately ) "

2392-10
" Although an insulation-résistance-value of not less than (1MΩ complies with the Regulations ), New-installations should not yield test results this low "

( 299MΩ ) . reason(s) , New-installation .

 

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Circuits must be designed that are fit for purpose andsuitable for the load they are intended to supply. They should be correctlydesigned in accordance with BS-7671.

Useful-junk .

New numberingsystem introduced for UK-only national regulations . :icon_bs:

In Amendment - 1 , UK national regulations willend in 100, 101,102, etc.

Regulation , 522.6.7 now 522.6.102

Regulation , 433.1.5 now 433.1.103

This will show-regulations that are specificto the ( UK only and not used in theEU )

 

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Useful-junk

1988 an agreement was reached that , voltage-levels across Europe should be unified at 230V , Single-phase & 400V , Three-phase with effectfrom , January 1[SUP]st[/SUP] 1995 .

Tables in the 17[SUP]th[/SUP] Editionhave been , recalculated to take account of the unified-voltage-levels . 230V & 400V

BS-7671: Made a Stand . :icon_bs:

Introduction of the ( Free-European-Marker in 1993 ) caused serious-problems for , UK electrical-contractors . IEE / IET wiring-regulations were held in high-esteem .they had , no-legal-status thatwould require Europeans who werecarrying out , installation-work in the UK to abide by them .

1992 , when the , IEE / IET wiring-regulation(s) became a (British-Standard ) BS-7671: giving them therequired-international-standing , from 2010 , BS-7671:

 

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Useful-junk: 2011:
Definition :- JPEL/64 . Regulation – GP / 10 . as at June 2011.
The , UK National-Committee-responsible for , BS-7671: is ( JPEL/64 ) :icon_bs:
J ... joint IET / BSI – committee .
P ... Power .
EL ... Electrical .
64 ... IEC– designation for Committees dealingwith , low-voltage-electrical-installations .

 

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BS-7671:2011: have stated the facts for us . :icon_bs:

2394 : RCCBs are still out-there ,
BS-EN-61009-1 ( RCBO ) BS-EN-61008-1 – ( RCCBs )

p/286 . BS-EN-61008-1:2004 + 12:2009
Residual-current-operated-circuit-breaker(s) without, integral-overcurrent-protection for household & similar uses ( RCCBs ) – Part 1 : General-rules
Introduction , Chapter -41 , 411.4.9.
411.4.9. . P/57
Where an , RCD is usedto satisfy the requirements ofRegulation , 411.3.2.2. the maximum-values of , earth-fault-loop-impedance in ,table- 41.5 may be applied for non-delayed RCDs to BS-EN-61008-1. & BS-EN-61009-1 . for anominal-voltage , ( Uo of 230V ) in such-cases , anovercurrent-protective-device shallprovide protection against , overload-current & fault-current in accordancewith Chapter – 43 .

411.3.2.2. Automatic-disconnection in case of a fault .
The maximum-disconnection-time stated in , Table -41.1 shall be applied to final-circuitsnot exceeding 32A .
Table 41.5.
Maximum , earth-fault-loop-impedance( Zs ) for non-delayed RCDs . to BS-EN-61008-1. & BS-EN-61009-1 for ( Uo of 230V ) Regulation – 411.5.3.

Table 53.4. Guidance on the selection of protective , isolation & switching-devices .

710.411.3.2.1. Medical-Locations .
Care shall be taken to ensure that ,simultaneous-use of many-items ofequipment-connected to the same-circuit , cannot-cause unwanted-tripping of the residual-current-protective-device ( RCD )

710.410.3.4. Exhibitions , Shows & Stands .
A cable-intended tosupply-temporary-structures shall beprotected at its origin by an RCD whose-rated-residual-operating-current , dosenot exceed 300mA , This device shallprovide a delay by using a device in accordancewith BS-EN-60947-2 , or be the ( S – type in accordance with BS-EN-61008-1 ) or BS-EN-61009-1for discrimination with RCDs protecting-final-circuits .

Note : The requirement for ,additional-protection relates to theincreased-risk of damage to cables in temporary-locations.

721.411.1 Electrical-Installations in Caravans & Motor-caravans .
Where-protection byautomatic-disconnection of supply is used ( Section – 411 ) an RCD – complying with , BS-EN-61008-1 . & BS-EN-61009-1, interrupting all-live-conductors’ shall be provided having the characteristics specified in Regulation –415.1.1. & the wiring-system shall include a circuit-protective-conductor which shall be connected to . Etc . refer . 721.411.1 (i) (ii) (iii)

740.410.3. Section – 740 .
Automatic-disconnectionof supply to the temporary-electrical-installation shall be provided at theorigin of the installation by one or more RCDs with a rated-residual-operating-current not exceeding 300mA , the RCD shall incorporate, time-delay in accordance with BS-EN-60947-2 , or be the ( S – type inaccordance with BS-EN-61008-1 ) or BS-EN-61009-1 , where necessary to provide discrimination with RCDs protecting-final-circuits .

740.411 , Note .
p/295 . Appx 3, Table – 3A . Time / current , characteristics of overcurrent-protective-devices & RCDs

am justbring it to your Attention . BS-EN-61008-1

 

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What’s in a Book.

Re-cap : GN-3 ,P/11 , offers Us Guidance. 2394 . What will help me in my ,Exams . ( Better-understanding )

Safety:
Electrical-testing inherently-involves some degree of Hazard .

It is the Inspector’s-duty to ensure his ( or her ) ownsafety , & that of others , in the performance of the test-procedures .

The safety-procedures detailed in , Health &Safety-Executive-Guidance , Note GS-38 .( revised )

Electrical-test-equipment for use by , electrician’s should be observed . When testing does not require the equipment orpart of an installation to be ( Live )

It should be made ( Dead) & ( Safety-isolated)

Guidance on ( Live & Dead-working ) Safety-Executive-publication , Memorandum of guidanceon the , Electricity-at-work-Regulations – 1989 ( HSR.25 )

Guidance on, Safe-isolation-procedures can be found in a ,best-practice-guide-published by the , ESC .

 

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What are the Objectives of the IET– Wiring-regulation(s) BS-7671:2008: 2011.

To ensure the ( Protection) of people & livestock from , fire , shock or burns from any installation thatcomplies with their-requirement’s.

 

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What in the Eyes of , The IET-Wiring-Regulations ( Cover) Main-cover , The Words , Wiring-Regulations.

Re-cap , TheRegulations cover both : ( What ?? ) :icon_bs:

Electrical-installation(s).
Electrical-equipment .

 

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It assumes that behind every Electrician thereis a Designer. :icon_bs:

Ohm’s-law , the current-flowing will depend on thevoltage-applied & the résistance of the current-path.

In the Eyes of ,BS-7671:2008:2011:
Limit the severity of , Electric-shock is the limitation of ,Earth-fault-loop-impedance .

As Electrician’s, we know this all too well . Electric-shock results from contact with a conductor that form-part of a circuit . ( Live )

Circuit-breaker(s) :- Overcurrent-protective-system will offer , no-protection
RCDs . RCBOs /MCB . RCD with an opening-current of 30mA . ( BS-7671: do not claim great expectations , Additional-protection ) May-do-so . 2392-10 . Can a RCD become faulty or is faulty . that’s why Testing is very-important .

GN-5 : The effects of an , Electric-shock ... ( Dependent on the current )
Depends on two-factor(s)

• Value of shock-current-flowing .
• Time for whichit flows . ... ( Additional-protection )

Human-body is composed largely of water, & has very-low-résistance ( Theskin has very-high-résistance )

 

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Just making you aware : ( Fixed-electrical-equipment )

Protection from Burns . 423 . P/77 :icon_bs:

Regulations provide a Table showing the , Maximum-allowable-temperatures-surfaces, that could be touched & thus-cause-burns .
From you point of view , Very-Young , Old , Infirm . Etc

Accessible-part of equipment within-arms-reach , refer

 

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Working my way around the Regulations .

Overcurrent-Protection. against Overcurrent . 43 . P/79 :icon_bs:

The term can bedivided into two-types of excess-current .

Overload-current(s) ... ( higherthan those intended to be present in the system )
Short-Circuit-Current(s)... ( These currents will only occurunder , fault-conditions )

-&-s. The type of fault which occurs when a Line-conductor comes in contact with aneutral-conductor is called : ( short-circuit-fault)

430.1. This chapter provides-requirements for theprotection of ( Live-conductors fromthe effects of Overcurrent )

Etc . describes how ( Live-conductors are protected by one-or-more-devices for the automatic-disconnection of the supplyin the event of Overload-current )

Note - 1, Live-conductors-protected against-overload in accordance with Section – 433 are also considered to be protection-against-faults, likely to cause overcurrents of a magnitude similar to overload-currents . Etc .refer

 

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2011- Note : P/55. 411.4.7. Table – 41.3. for the types & ratings of overcurrent-devices , listedmay be Used-instead of calculation . :icon_bs:


► Taken from , Old-notes . 16[SUP]th[/SUP] Edition .

Overload-provisions are met , if the setting of the protective-device: ( In )

Exceeds the circuit-design-current . ( Ib )
Does Not-exceed the rating of the smallest-cable-protected .

The current for operation must not be greater than ( 1.45 times the rating ) of the smallest-cable-protected .

BS-EN-60898 . ( B –type ) requires a 32A Circuit-breakerto operate within one-hour when carryinga current of 40A .
Fig – 3.4. P/301 ... ( 5 x 32A = 160A) High-current-operation

Maximum-loop-impedance. ( Ia, Ief )

Amp ÷ current = sec .
32A ÷ 230v = 0.1
Zs ≤ Uo / Ia .
Zs ≤ 230 / 160 .
Zs ≤ 1.4375Ω ... 41.3 , Zs - 1.44Ω

“ Instantaneous“ which is actually within ( 0.01 s ) 10mS . ( Current for time. 0.1s to 5s. ) Fig – 3.4. P/301

Fig . 3A4 . 3A6 .

B . 3 x 6A = 18A or 5 x 6A = 30A
C . 5 x 6A = 30A or 10 x 6A = 60A
D . 10 x 6A = 60A or 20 x 6A = 120A

When does a Circuit-breaker trip . B , 3 - 5 .

The Circuit-breaker-side of the RCBO. BS-EN-61009-1 , Fig . 3A4 . 3A6 . Overcurrent-characteristics

433: P/81 . Protection against ,Overload-current .

Reason : Overload-protection is to safeguard-Conductors & Cables .
Overload-protection is related to the ,Current-carrying-capacity of the cables. Etc

 

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Re-cap : - Regulations 522.6.101 / 522.6.102 , 413.3 , 314.1 & 701 cover all applications for RCDs

 

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Extracts . taken

Health and Safety at Work Act 1974

The Health and Safetyat Work Act 1974 and the Electricity at Work Regulations 1989 are statutorydocuments and non-compliance constitutes a criminal offence.

Electricity at Work Regulations 1989

Because of the widerange of work covered by the regulations, the requirements are framed ingeneral terms , the Memorandum of Guidance on the above regulations, a clearcase is made for using RCDs as an additional safeguard forearthing ( Reg - 8 ). Also under clause 12 ( Isolation ), it advises that the use of , RCDs will meet the provision of ( Isolation) check – Table 53.4.