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( MEIWC)

Description of ( MWs)

The minor work mustbe so described that the work that is the subject of the Certificate . can bereadily identified .

120.3. & 133.5.
No departures areto be expected except in most . unusual circumstances . 633.1.

Installationdetails .
Method of faultprotection must be clearly identified .Automatic disconnection of supply . ADS

If the existinginstallation lacks either an effective means of earthing or adequate . mainequipotential bonding conductors . this must be clearly stated in the spaceprovided – 633.2.

Recorded departures. form BS-7671 . may constitute . non-compliance with the . Electricity Safety. Quality & Continuity Regulations – 2002 . as amended . or the Electricity at Work Regulations 1989 . it is important that the Client isadvised immediately in Writing .

Essential Tests .
Relevant provisionsof part 6 . Inspection & Testing –BS-7671 . must be applied in full to all ( MWs )

Where asocket-outlet is added to an existing circuit . it is necessary to :
i) establish that the earthing contact of thesocket-outlet is connected to the ( MET)
ii) measure the ( IR ) of the circuit that has been added to . &establish that it complies with Table 61 .
iii) measure the EarthFault Loop Impedance . to establish that themaximum permitted disconnection time is [Not Exceeded ]
iv) Check that the polarity of the socket-outletis correct .
v) if the work is protected by an . RCD . verifythe effectiveness of the ., RCD .
 
Inyour own words state what we mean by “ Basic protection “ & how is itachieved :

GN-3. 2012
Basic protection .
Sect– 416 . 416.2.
Ismost usually provided by [Insulation ] & or [ Enclosures ] the inspection of this measure is to check that insulation has not beendamaged during installation & that [Enclosures ] have been selected for atleast . IPXXB or IP2X .& for top surfaces . at leastIPXXD or IPX4 . & are not damaged .

(IR ) is of course a fundamental test to be carried Out .

 
Inyour own words state what we mean by “ fault protection “ & how is it achieved .

Faultprotection by ( ADS )
Summaryof RCD requirements :
AnRCD should be cable of disconnecting allLine conductors at substantially the same time .
AnRCD cannot be used for fault protection on it’s own .

AnRCD on it’s own does not provide protection against overcurrents .
Overcurrentprotection is provided by a [ fuse or miniature circuit breaker – MCB] Exams’ . Combined :- RCD & MCB . RCBOs

RCCBs. BS-EN-61008-1 . p/34 .
Residual current operated circuit/breaker . [ Without integral overcurrent protection] for it’s time – household &similar uses

RCBOs. BS-EN-61009-1 . p/34 .
Residual current operated circuit/breaker . [ With integral overcurrent protection ] – household & similar uses .

Basicprotection : can be achieved by either preventing the current from passingthrough a body or by limiting the valueof the current to a non-hazardous level .
Faultprotection : can be achieved by similarmethods . but also by reducing the time the body is exposed to the fault .therefore aiming to reduce the time to a non-hazardous level .

Theprotective measure available :

Automaticdisconnection of supply – ( ADS )

Basicprotection 411.2.: can be achieved by either preventing the current from passing through a body or by limiting the value of thecurrent to a non-hazardous level .
To achieve basic protection the electrical equipmentmust rather employ the requirements of basic insulation of Live parts . – 416.1. :

Live parts . such as energizedconductors . must not be accessible . &
Conductiveparts . which are accessible suchas “ Metal pipes “ must not be hazardous Live .


 
610.1. it should be noted the regulation 610.1.requires inspection & testing to be carried out during the erection stageof the installation . as well as on completion .

132.14.1.
Verification ofPolarity : Single-pole device in a TN- or TT system .
530.3.2:
Must be verifiedthat . single-pole devices for protection or switching are installed in lineconductors only .

Inyour own words state what we mean by “ fault protection “ & how is it achieved .

GN-3 :
Fault Protection .
The various methodsof fault protection are classified in a number of [ subsections ] BS-7671 -

Sect 411 . –418.1.
Automaticdisconnection of supply – ( ADS )
Method 1 : ( ADS )
For each circuit .automatic disconnection is required & . although the main part of .Verification is measurements of earth fault loop Impedance in order to confirm sdisconnectiontimes . there are inspection aspects to consider for verifying ( ADS ) follows :

2392-10 .
542.3. Earthing conductor .
Sect – 543 .Circuit protective conductors .
Sect – 544 .protective bonding conductors .
- Mainbonding conductors .
- Supplementary bonding conductors . where required.

312.2. The earthing system must be determined .
TN-C-S . - Protective multiple earthing – ( PME )
TN-S system .
TT system – Earth Electrode(s).
 
Fused connectionunit :
Correct rating& fuse – 533.1.
Complies withBS-1363-4 – 559.6.1.1. – vii .

Cooker control unit.
- Sited to one side& low enough for accessibility & to prevent flexes trailing across radiant plates – 522.2.1.
- Cable to cookerfixed to prevent strain on connections – 522.8.5.

Test Method 2 : (R[SUP]2 [/SUP] )
Test Method 1: ( R[SUP]1[/SUP] + R[SUP] 2 [/SUP])

Radial circuit oflength about 55m with 2.5mm[SUP]2 [/SUP] Line & protective conductors should havean ( R[SUP]1[/SUP] + R[SUP] 2 [/SUP]) résistance .
Length of circuit –55m
Résistance of cableis . 7.41 mΩ/m ( at 20°C)
Theoretical minimum d.c. résistance = ( 55 x 2 x7.41 ) / 1000 = 0.82Ω
 
Additions &Alterations .

132.16. Every addition & alteration to an existinginstallation must comply with the current edition of BS-7671 . & must notimpair the safety of the existing installation . in this respect . in order to verify that the addition & alterationto an electrical installation complies with BS-7671 . the existing installation must beinspected & tested to confirm the safety of the addition & alteration . 633.1. 633.2.

- Protective conductorcontinuity .
- Earth fault loopimpedance .

633.2. Whilst there is no obligation to inspect & test any part of the existinginstallation that does not affect & is not affected by the addition & alteration. observed departures are required to be noted in the comments box . of ( EIC ) single-signature . or multiple-signature . &minor work certificates .


 
Recording the .Prospective Fault Current . ( PFC )

Both the ( EIC ) & the ( EICR ) contain a box headed . Nature of Supply Parameters . . whichrequires the . ( PFC ) at the [ Origin ] to be recorded .
The value to berecorded is the . Greater of either the short-circuit current . – between liveconductors . or the earth fault current . between line conductor(s) . & the. ( MET )

if it is considered necessary to record values atother relevant points . they can be . recorded on the . Schedule of Test Results . where the protective devices used . at theOrigin have the necessary rated breaking capacity . & devices with similar breakingcapacity are used throughout the installation . it can be assumed that theregulations are satisfied in this respect for all . distribution boards .

 
PhaseSequence Testing . 612.12.

Thiscame up on Exams . 2391-10 ..

The 17[SUP]th[/SUP] Edition . introduced inregulation – 612.12. a requirement to [ Verify ] that the . phase-sequence ismaintained for multiphase circuits within an installation . in practice . thiswill be . achieved by checking polarity & connections throughout theinstallation .


Optionally& occasionally . the inspector may wish to . check phase sequence by usinga phase rotation tester . either .
- Rotating disk type . Or
- Indicator lamp type .



 
Verification in Medical Locations . 710 :

710.61. The installation & testing of theseinstallations is very much a . specialist area & only the general requirements of .BS-7671 . are provided in this GN- .initial verification is carried out by an inspection & functional tests ofthe isolation IT system . equipment including the . insulationmonitoring devices . testing is required to measure the . leakage current ofthe output circuit of . Medical IT isolating transformers . & measurementof the résistance of the . supplementary equipotential bonding .

 
Purposeof . Periodic Inspection & Testing . 621.2. is to provide an Engineering view . on whether or not theinstallation is in a satisfactory condition where it can continue to be usedSafety .

 
Purposeof . Periodic Inspection & Testing . 621.2. is to provide an Engineering view . on whether or not theinstallation is in a satisfactory condition where it can continue to be usedSafety .

Itshould be noted that the initial . sample size is only based on a . walk-round .& consultation of . records . further . that what may at first appear to begood . E.g. the quality of maintenance . may turn out to be poor during the detailed inspection & testing .

Suggestedprocedure for setting . Initial & adjusted sample size .

Conductinitial “ Walk round “ survey &establish initial sample size .

Carryout Inspection & Testing . based on initial sample size .

Good results .
Goto final report .

Intermediate/ poor results .
Increasesample size . or discuss with Client . whether further investigation is required .
 
Stillthe same . 2391-10 :

Low-résistanceohmmeters . BS-EN-61557-4 .
(IR ) testers . BS-EN-61557-2 .

Earthfault loop impedance testers . BS-EN-61557-3 .
Thismeans that the instrument should cut OFF the test current after [ 40mS ] Etc .

(RCD ) testers . BS-EN-61557-6 .
Reminder . 2392-10 . -&-s
Tocheck RCD . operation & to minimise danger during the “ Test “ the test current should be appliedfor no longer than [ 2s ]

Phaserotation instruments . BS-EN-61557-7 .
Exams: Mechanical . visual & / or audiblemeans .
 
I'm just bumping some of the older threads in the general electrical forum that had a lot of replies. They might not be current topics, if they're not, just ignore them and they'll soon drop off the list. If you DO wish to add a reply and get the conversation going again, feel free to do so. Your input might help somebody else in the future.
 
I'm just bumping some threads in the Electrical Forum, don't mind me while I do this, you don't have to respond to them. Although if they are still current topics, and you do wish to reply, you're welcome to. Keep the thread on-topic and make sure you stick to the forum rules though.
 

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