Re-take - Useful Information for 2394 :

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O.S.G. Electrical supplies to Furniture :book:

My point .

543.2.1. 543.2.6.
There is no general requirement to ensure electrical continuity across the metallic frame of an item of furniture unless the frame has been designed to be used as a protective-conductor .

 

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3.1. O.S.G. Protective device - 2008 & 2011. ◄ Passed tense
The consumer unit ( or distribution board ) contains devices for the protection of distribution circuits and final circuit against:

i) overload
ii) short-circuit
iii) earth fault ........... Etc

Functions i and ii are carried out usually by one device, i.e. a fuse or circuit-breaker.
Function iii may be carried out by the fuse or circuit-breaker provided for functions i and ii or by an RCD

An RCBO, being a unit with a combined circuit-breaker and RCD, will carry out functions i, ii, and iii .

Things has changed . (A3) 2015 . ▼ :book:

3.1. O.S.G. Protective device
The consumer unit ( or distribution board ) contains devices providing:

(a) Overload protection ✓
(b) Short-circuit protection ✓
(c) Fault current protection ✓
(d) Additional protection: RCD(s) ✓

Functions a, b, and c, are usually carried out by one device, i.e. a fuse or circuit-breaker.
An RCBO, being a unit with a combined circuit-breaker and RCD, will carry out functions a, b, c, and d .

 

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Learning curve only .

GN-3 . 2008: ◄ :book:

4) rule of thumb figures .
As a rule of thumb, the measured value of earth fault loop impedance for each circuit at the most remote outlet should not exceed 0.8 of the relevant value in the BS-7671 tables. This takes into account the increase of résistance of the conductors with the increase of temperature due to load current and errs on the side of safety .

Another method is to use the rule of thumb as described in Appendix 4 of BS-7671:2011: ◄

Circuit has a measured Zs of 0.51Ω
BS-EN-60898-1 circuit-breaker . Type C 32A
Table 41.3 . maximum permissible Zs for the circuit is 0.72Ω

multiply the maximum permitted value by ( 0.8 ) 0.72 x 0.8 = 0.57Ω ( This now becomes the maximum permissible value ))

Question is . Higher or lower .

As the measured value is less than . ?? will the circuit be acceptable .

BS-7671:2015 ◄
Using a factor of 0.8
Table 41.3 . maximum permissible Zs for the circuit is 0.68Ω
BS-EN-60898-1 circuit-breaker . Type C 32A

 

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Learning curve only . (( Look at the dates ))

Q ) When taking impedance measurement at ambient temperature a rule-of-thumb correction factor may be applied to the values in BS-7671: to take into account the increased résistance of the conductors due to load current is ?

0.75
0.8
0.5
1.2

GN-3 BS-7671 Amd 1 2002. ◄ Past tense :book:


4) Rule of Thumb figures ( 0.75 )
As a rule of thumb, the measured value of earth fault loop impedance for each circuit at the most remote outlet should not exceed three-quarters of the relevant value in the BS-7671 tables. The three-quarters figure allows for a reduced cross-section protective conductor and errs on the side of safety.

GN-3 . ◄ :book:
2008:
2011:
2015:

4) rule of thumb figures (0.8)
As a rule of thumb, the measured value of earth fault loop impedance for each circuit at the most remote outlet should not exceed 0.8 of the relevant value in the BS-7671 tables. This takes into account the increase of résistance of the conductors with the increase of temperature due to load current and errs on the side of safety .

 

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411.8.1.3. Requirement for fault protection . :icon_bs:
Extracts : 2015
Where a circuit-breaker is used, the maximum value of earth fault loop impedance (Zs) shall be determined by the formula in Regulation 411.4.5.

Alternatively, the value specified in Table 41.6. may be used instead of calculation for the nominal voltages (Uo) and the types and ratings of overcurrent devices listed therein .

Reduced low voltage system(s) :icon_bs:

Table 41.6.
Maximum earth fault loop impedance (Zs) for 5s disconnection time and Uo of 55V (single-phase) and 63.5V (three-phase)
see Regulations 411.8.2. and 411.8.3.

BS-EN-61558-1:2005+A1:2009
411.8.4.1. (i)
717.411.6.2. (ii)
717.413.

BS-EN-61558-2-23. Particular requirements for transformers for construction sites.
411.8.4.1 (i)

Voltage of 65V to earth, three-phase.
55V to earth , single-phase will give protection against severe electric shock .

They therefore recommended that portable tools used on construction sites . etc 110V centre-tapped transformer .

What’s new . (A3) - 2015 .

Note 1: The circuit loop impedance's have been determined using a value for factor Cmin of 0.95.
Note 2: The circuit loop impedance's given in the table should not be exceeded when:
(i) the line conductors are at the appropriate maximum permitted operating temperature, as given in Table 52.1. and
(ii) the circuit protective conductors are at the appropriate assumed initial temperature, as given in Table 54.2. to 54.5.

if the conductors are at a different temperature when tested, the reading should be adjusted accordingly, see Appendix 14.

Note 3 : Where the line conductor insulation is of a type for which Table 52.1. gives a maximum permitted operating temperature exceeding 70°C, such as thermosetting, but the conductor has been sixed in accordance with Regulation 512.1.5:
(i) the maximum permitted operating temperature for the purpose of Note 2 (i) is 70°C and
(ii) the assumed initial temperature for the purpose of Note 2 (i) is that given in Tables 54.2. to 54.4. corresponding to an insulation material of 70°C thermoplastic.

Note 4 : Data for fuses of rating exceeding 200A should be obtained from the manufacture.

 

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RVS .

in the Eyes , H&S Executive accepts that a voltage of 63.5V to earth three-phase
55V to earth , single-phase . will give protection against severe electric shock .

PS. don’t be complacent here in Exams . by calculation !! . rule out nothing from City & Guilds :30:

Alternatively, the value specified in Table 41.6. may be used instead of calculation for the nominal voltages (Uo) and the types and ratings of overcurrent devices listed therein .

 

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(A3) P/35 . Short-circuit current . :icon_bs:
An overcurrent resulting from a fault of negligible impedance between live-conductor(s) having a difference in potential under normal operating conditions .

Not in Definitions .

Short circuit(s)
A short-circuit is the current that will flow when a “ dead short ” occurs between live-conductors ( Line to neutral ) for single-phase
Line to line for three-phase .

(PSCC) Prospective short circuit current is the same , but the term is usually used to signify the value of short-circuit at , Fuse , Circuit-breaker positions .

You’re reason is ; Fuses and circuit-breakers . (( protecting the circuit conductors from damage ))

The meaning of the word “ Protection ” as used in Regulations & GN-3 in the electrical industry , is no different to that in everyday use . People protect themselves .

Protection against mechanical damage .

The word “ Mechanical ” is somewhat misleading in that most of us associate it with machinery of some sort .
in fact a electrical overcurrent left uninterrupted for too long can cause distortion of conductors and degradation of insulation . both of these effects are considered to be “ Mechanical damage ”

re-cap . The Regulations tell us . Let us start by considering the (( ways )) of preventing “ Mechanical damage ” caused by physical impact and the like . Etc

 

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A bathroom is “ an at risk ' location ”

Protective Measure: Electrical separation .
413.3.6. & 418.3.

This method relies on a supply from a safety source such as an isolating transformer to BS-EN-61558.

BS-EN-61558-2-5:2010. Particular requirements for shaver transformers and shaver supply units .

The two main principles underlying protection by electrical-separation is that neither the source of the supply nor any live parts of the separated circuit is connected to any other circuit or to Earth.

Thus, in the event of a single fault to an exposed-conductive-part of equipment in the separated circuit, fault protection is afforded because there is no path for fault current to return to the source. For an installation in a dwelling, the only likely application of the use of electrical separation is a shaver supply unit complying with BS EN 61558-2-5.

This protective measure is limited to the supply of one item of current-using equipment supplied from one unearthed source with simple separation. The source of supply is an isolating transformer conforming to BS-EN-61558.

An example of electrical separation is a shaver supply unit.
because the secondary side of the transformer (which supplies the shaver) is isolated from the mains; in Theory only ; “ think of the shaver being supplied by a big battery ” !

Electrical separation . :icon_bs:
This method relies on a supply from a safety source such as an isolating transformer to BS-EN-61558-2-5 which has no earth connection on the secondary side. In the event of a circuit that is supplied from such a source developing a live fault to an exposed-conductive-part , there would be no path for shock current to flow .

BS-EN-61558-2-5:2010.
Sec 701
533.1.5.(ii)
701.512.2
701.515.3.(ii)
701.512.3 Appx 6
Cond. Report item 6.3.....

6.3. Shaver sockets comply with BS-EN-61558-2-5 formerly BS-3535 ( 701.512.3 .

413.3.6 . refer
No exposed-conductive-parts of the separated circuit shall be connected either to the protective conductor or exposed-conductive-parts of other circuit, or to Earth .

Note: if the exposed-conducive-parts of the separated circuit are liable to come into contact, either intentionally or fortuitously, with the exposed-conductive-parts of other circuits, protection against electric shock no longer ((depends solely on protection with )) electrical separation but also on the protective provisions to which the latter exposed-conducive-parts are subject.

418.3.
Electrical separation for the supply to more than one item of current-using equipment .

Where the measure is used to supply two or more items of equipment from a single source, a warning notice complying with Regulation 514.13.2. shall be fixed in a prominent position adjacent to every point of access to the location concerned .

Note: Electrical separation of an individual circuit is intended to prevent shock currents through contact with exposed-conducive-parts that may be energized by a fault in the basic insulation of the circuit .

 

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Introduction to the first amendment ; Deleted by BS-7671:2008: Amendment 3 .
Introduction to the second amendment ; Deleted by BS-7671:2008: Amendment 3 .

P/4 . Introduction to BS-7671:2008(2015) :icon_bs:

The Regulations apply to the :
- Design
- Erection
- Verification of electrical installations
- Additions and alterations to ((Existing installations))

((Existing installations)) that have been installed in accordance with earlier editions of the Regulations may Not comply with this edition in every respect .

:13: This does Not necessarily mean that they are unsafe for continued use or require upgrading . :deal:

 

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530.3.4 - Pass tense ............. BS-7671:2008: (2011) :icon_bs: ( PS look at the dates )
For an installation with a 230V single-phase supply rated up to 100 A that is under the control of ordinary persons, switchgear and controlgear assemblies shall either comply with BS-EN-60439-3 and Regulation 432.1 or be a consumer unit incorporating components and protective devices specified by the manufacturer complying with BS-EN-60439-3 including the conditional short-circuit test described in Annex ZA of BS-EN-60439-3 the standard.

► BS-EN-60439-3:1991 .. Pass tense
Particular requirements for low-voltage switchgear and controlgear assemblies intended to be installed in places where unskilled person have access to their use . Distribution boards .

( A3 - 2015) Regulation 530.3.4. (( changes have been made )) :icon_bs:

530.3.4 For an installation with a 230V single-phase supply rated up to 100A that is under the control of ordinary persons, switchgear and controlgear assemblies shall either comply with BS-EN-61439-3 and Regulation 432.1 or be a consumer unit incorporating components and protective devices specified by the manufacturer complying with BS-EN-61439-3, including the conditional short-circuit test described in Annex ZB of BS-EN-61439-3 the standard.

BS-EN-61439-3:2012: CCUs
Low-voltage switchgear and controlgear assemblies Distribution boards intended to be operated by ordinary persons ( DBO)

Intro to Amd 3
421.1.201.
530.3.4.

P/40 . D.N.O. Distribution network operator
560.6.9 Note 1 .

Note 1 : The parallel operation of a private source with the public supply network is subject to authorization by the distribution network operator (DNO) This may require special devices, for example to prevent reverse power. Refer also to Section 551, the DCode (Distribution Code of licensed distribution operators ) and ENA Engineering Recommendations G83/2 and G59/3.

 

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Chapter 61
Initial Verification :icon_bs: 2015

610.1. Every installation shall, [during erection] and [on completion] [before being put into service] be inspected and tested to verify, so far as is reasonably practicable, that the requirements of the Regulations have been met .

You’re Q - New installation

Q) List the Three-stages in a new installation when inspection and testing should be carried out .
i) during erection.
ii) on completion . and
iii) before being put into service .

 

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Something I knocked up .

-&-s are looking for ; Principle and responsibilities .

Q) Technical knowledge , practical skills, experience of the type of installation to be inspected and to employ adequate testing equipment are the factors that determine the competence of the test engineer.

i) BS-7671:2008:2015; .. non-statutory
ii) Guidance Note 3 .. non-statutory
iii) GS-38 .. non-statutory . PS read the questions carefully . -&-s . C&Gs will trip you up .

Identify and state the legal status of Two publications that the test engineer will have to comply with when carrying out the inspection and testing process .
1) Health and Safety at Work (etc) Act 1974 .. Statutory
2) Electricity at Work Regulations 1989 .. Statutory

Please read carefully ;
2394. Comments .
Abbreviations such as EWR and HSWA are acceptable. Candidates must correctly identify whether these are ACT or REGULATIONSs in order to achieve the marks .

The candidate could have offered other health and safety regulations or reference to the Health and Safety at Work Act as a possible answer .
The particular document must relate to the process of inspection and must be a stator document .

Duty holder , to ensure that electrical systems used at work under their control are safe . (( You have a duty of care , responsibilities ))

Q) State the title given in law to the inspector whilst carrying out the inspection of an electrical installation.
The Electricity at Work Regulations and the term “ Dutyholder ” refers to anyone having a duty of care to others .

Q) Identify the British Standard for electrical test instruments that are to be used by the test engineer to obtain measurement values on circuit within an installation .

BS-EN-61557 .. Electrical safety in low-voltage distribution systems up to 1000V a.c. and 1500 d.c. Equipment for testing, measuring or monitoring of protective measures . General requirements .

 

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Refraction ) The particular document must relate to the process of inspection and must be a statutory document .

 

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Something I knocked up .

PS read the wording in the questions carefully . C&Gs will trip you up

Making you aware off .

An attic extension is to be carried out in a domestic installation .
The lights are to be taken from the first floor lighting circuit and a new radial circuit consisting of 6 double sockets is to be installed.

( existing )
( new )

Q) Identify four documents that needs to be completed and given to the client .

Electrical Installation Certificate .. PS accompanied by ??? What

Schedule of Inspection ( for new installation work only )
Generic Schedule of Test Result .............. (( Wording used in Regulations & GN-3 ))
Minor Electrical Installation Work Certificate .............. (( for the additional lighting points ))

P/416 . Electrical Installation Certificate
The Electrical Installation Certificate is to be used only for the initial certification of an new installation or for an addition or alteration to an existing installation where new circuits have been introduced .

P/418 . Minor Electrical Installation Work Certificate
The Minor Electrical Installation Work Certificate is intended to be used for additions and alterations to an installation that do not extend to the provision of a new circuit .

Examples . include the :
- addition of socket-outlets
- lighting points to an existing circuit
- the relocation of a light switch etc .

This Certificate may also be used for the replacement of equipment such as accessories or luminaires .

 

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Chapter 41 . Protection against Electric Shock .
410 Introduction
This chapter with protection against electric shock as applied to electrical installations .

I will put the question in a way; (Four)
How many “ protective measures ” against electric shock are allowed by the wiring regulations BS-2008:2015:

learning curve .

P/53 . 410.3.3. :icon_bs:
In each part of an installation one or more protective measures shall be applied, taking account of the conditions of external influence .
The following protective measures generally are permitted:
(i) Automatic disconnection of supply (Section 411)
(ii) Double or reinforced insulation (Section 412)
(iii) Electrical separation for the supply to one item of current-using equipment (Section 413)
(iv) Extra-low voltage (SELV) and (PELV) (Section 414)

The protective measures applied in the installation shall be considered in the selection and erection of equipment.
For particular installations see Regulations 410.3.4. to 9

Note: In electrical installations the most commonly used protective measure is automatic disconnection of supply .

 

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(A3) P/424. Electrical Installation Condition Report

Condition Report :icon_bs:

Amendment 3 will make a small number of changes to the electrical installation condition report and associated notes, including a requirement to carry out an inspection within an accessible roof space where electrical equipment is present in that roof space.

Section D, Extent and Limitations of Inspection and Testing .

The inspection and testing detailed in this report and accompanying schedule have been carried out in accordance with BS-7671:2008 (IET Wiring Regulations ) as amended to ........................................................................

It should be noted that cables concealed within trunking and conduits, under floors, in roof spaces, and generally within the fabric of the building or underground. have not been inspected unless specifically agreed between the client and inspector prior to the inspection . An inspection should be made within an accessible roof space housing other electrical equipment .

 

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(A3) Section 714 Outdoor Lighting Installations . :icon_bs:

In 2008 some major changes to the requirements for outdoor lighting installations were introduced, covering requirements for:

• car parks;
• gardens;
• parks;
• places open to the public;
• illumination of monuments; and
• floodlighting.

These will be retained in Amendment 3, along with the recommendations for additional protection by a 30mA RCD for telephone kiosks, bus shelters, advertising panels and town plans.

Amendment 3 will make only minor changes to outdoor lighting installations. One important change will be that individual circuits will be required to be isolated.

Extracts .

714.537. Isolation & switching .
714.537.2. Isolation
714.537.2.1. General

714.537.2.1.1. Every circuit shall be capable of being isolated individually from each of the live supply conductors , except as detailed in Regulation 537.1.2.

714.537.2.1.201.
Where it is intended that isolation and switching is carried out only by instructed persons and subject to suitable provisions being made so that precautions can be taken to prevent any equipment from being inadvertently or unintentionally energized, for TN systems, the means of switching the supply ( On-load ) and the means of isolation is permitted to be provided by a suitably ( rated fuse-carrier )

 

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RP/308 . BS-EN-60898
Connecting devices for low-voltage circuits for household and similar purposes.

BS-EN-61009-1:2004+13:2012.
Electrical accessories.
Residual current operated circuit-breakers with integral overcurrent protection for household and similar uses (RCBOs)
Table 41.3.
411.4.9.

(( Point to remember )) ▼ :icon_bs:

BS-7671:2008:2015: Only provides us with information, which is relevant to equipment which we could purchase and fit at the time it was published
Therefore, the regulations only deal with BS-EN-60898 circuit-breaker(s) and BS-EN-61009-1 RCBOs

BS-EN-60898 is the most onerous Standard written for the manufacturing and testing of circuit breakers.

By definition its title ‘Specification for circuit breakers for overcurrent protection for household and similar installations’, implies that the circuit breaker will be generally used on final circuits. The scope of the Standard states that the circuit breakers are designed for use by uninstructed people and are not designed to be maintained. This is further emphasised by the many tests required to ensure the safety of the person who will return the circuit breaker to service. It does not mean that this Standard only refers to circuit breakers in domestic situations. All buildings have final circuits, and in many instances the first person attempting to reset a circuit breaker could be classed as uninstructed. The Standard recognises this by including the words ‘ and similar installations’ in its title.

Part 2 of BS-7671:2015: defines an instructed person (electrically) as ‘ a person adequately advised or supervised by skilled persons (as defined) to enable that person to perceive risks and to avoid hazards which electricity can create

 

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Electrical Glossary . :svengo:

Crimp: a permanent, solderless connection between wires achieved by compression in the conductive tubing of the crimp connection or terminal
Dolly: type of switch in the form of a typically vertically aligned lever . see toggle .
Installation method : immediate environmental context within which a length of wire / cable is installed .
Luminaire: French word for lamp or light commonly used by electricians .
mA) milliamp, 1 / 1000 of an amp .

Raggles: Scottish term for chasing . PS, am raggling out the wall .

 

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(A3) GN-3. Requirements for inspection and testing .

Extracts
it is important that the competency of the skilled person carrying out the periodic inspection and test is of the appropriate level, having gained sufficient education, training or practical skills, and knowledge to be fully conversant with the aspects required of carrying out such an important inspection .

The Inspector

BS-7671:20082015) has to State the facts . :icon_bs:
requires that the inspection and testing shall be carried out by a Skilled persons, competent .

with regards to verification he/she must have .

Sufficient technical knowledge
( i.e. fully versed in the inspection and testing requirements contained in BS-7671:2015)

relevant practical skills .
( i.e. have sufficient practical skills to carry out the inspection and test procedures outlined in Guidance Note 3 ) :book:

appropriate testing equipment .
Instruments used in the testing process ( where the values are to be recorded in the generic schedule of test results ) must comply with the appropriate parts of BS-EN-61557 . :deal:

P/35. Skilled person (electrically) Person who possesses, as appropriate to the nature of the electrical work to be undertaken, adequate education, training and practical skills, who is able to perceive risks and avoid hazards which electricity can create.

Note1 : The term “(electrically)” is assumed to be present where the term “ skilled person ” is used throughout BS-7671.

O.S.G. This book is the side companion to the Wiring Regulations

 

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A “ duty of care ” responsibility makes the test engineer a “ duty holder ” for the duration of the inspection and testing process

The tile in law placed upon the test engineer is that of “ duty holder ”

2394 / 2395
The “ duty holder ” used in the Electricity at Work Regulations refers to the person . (( responsible for the electrical installation ))

The Electricity at Work Regulations identifies anyone taking control of, or responsibility for, an electrical system as a “ duty holder ” ( Memorandum of Guidance Regulation 3 item 55 ) “ duty holder’s ” have a duty to ensure the safety of themselves and others .

 

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Facts . :13:
As an Inspector to be . 2394 .

(IET) is the largest multidisciplinary professional engineering institution in the world.

Non-statutory
The Guidance Notes are published by the Institution of Engineering and Technology and are intended to be explanations of the requirements of BS-7671:2008(2015)

As the Guidance Notes are for “ Guidance ” only they must not be used independently of BS-7671:2008(2015) for ensuring compliance .

Guidance Note 3 is based upon the requirements of Part 6 in BS-7671:2008(2015)

As part of the competence requirement, the inspector must have a sound working knowledge of the test methods as described in the Guidance Note.

it provides details of the methods to be used for carrying out the tests as required by BS-7671:2008(2015) for both New and Old installations, it also provides detailed inspection check list to comply with the requirements and gives details of the instrument(s) to be used when carrying out the testing process .

 

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Appendix 6 ( informative ) P/413 refer :juggle2:

Certification and Reporting

So there is no screw ups in wording from : BS-7671:2008(2015) & GN-3 . in Exams .

(i) The Electrical Installation Certificate required by Part 6 should be made out and signed or otherwise authenticated by a ( skilled person or persons ) Etc .
(ii) The Minor Work Certificate required by Part 6 should be made out and signed or otherwise authenticated by a ( skilled person or persons ) Etc .

(iii) The Electrical Installation Condition Report required by Part 6 should be made out and signed or otherwise authenticated by a ( skilled person or persons in respect of the inspection and testing of an (( existing installation ))

(iv) Skilled persons will, as appropriate to their function under (i) (ii) and (iii) above , have a sound knowledge and experience relevant to the nature of the work undertaken and to the technical standards set down in these Regulations , be fully versed in the inspection and testing procedures contained in these Regulations and employ adequate testing equipment .

 

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The English language has three basic tenses: past, present, and future.

Amendment 3 of BS-7671:2008. is expected to be published on the 1st January 2015 and is intended to come into effect on 1st July 2015.

From January 2015, the 2382-15 . 17[SUP]th[/SUP] Edition becomes the only 17[SUP]th[/SUP] Edition qualification available as the older 17[SUP]th[/SUP] Edition course is being retired.
Electricians will need to update their qualification to the new 17[SUP]th[/SUP] Edition by July 2015 in order to stay current.

Periodic inspection and testing . ( look at the dates )

GN-3 (BS-7671:2008,2011,(2015)
Purpose of periodic inspection and testing

(2008) The purpose of periodic inspection and testing is to provide, so far as is reasonably practicable, for .

3.1. (2011) The purpose of periodic inspection and testing is to provide an engineering view on whether or not the installation is in a satisfactory condition where it can continue to be used safely .
3.1. (2015) The purpose of periodic inspection and testing is to provide an engineering view on whether or not the installation is in a satisfactory condition where it can continue to be used safely .

3.8. GN-3 (BS-7671: 20112015)
Requirements for inspection and testing .

The purpose of periodic inspection and testing is to provide an engineering view on whether or not the installation is in a satisfactory condition where it can continue to be used in a safe way .

GN-3 (BS-7671: 2011,(2015)
1.4. Additions and alterations . 132.16. 633.1. 633.2.

Every addition or alteration to an existing installation must comply with the current edition of BS-7671: and must not impair the safety of the existing installation. In this respect, in order to verify that the addition or alteration to an electrical installation complies with BS-7671: the existing installation must be inspected and tested to confirm the safety of the addition or alteration, including for example.

• protective conductor continuity
• earth fault loop impedance

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

(BS-7671: 2011,(2015)
132.16 - Additions and alterations to an installation

No Additions and alterations, temporary or permanent, shall be made to an existing installation, unless it has been abstained that the rating and the condition of any existing equipment, including that of the distributor, will be adequate for the altered circumstances, Furthermore, the earthing and bonding arrangement, if necessary for the protective measure applied for the safety of the addition or alteration, shall be adequate.

 

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Learning curve. Only

Basic voltage drop calculation

Single-phase
To calculate the voltage drop in volts the tabulated value of voltage drop ( mV/A/m) form Appendix 4 of BS-7671: has to be multiple by the design current of the circuit (Ib) the length of run in metres (L) and divided by 1000 ( to convert to volts )

Voltage drop = ( mV/A/m) . L Ib

Where :
( mV/A/m) tabulated value of voltage drop in mV per amp per metre form Appendix 4 of BS-7671:
L) the length of run in metres (m)
Ib) design current of circuit (A)

The requirements of BS-7671: are deemed to be satisfied for a 230V supply, if the voltage drop between the origin of the installation and a socket-outlet or current-using equipment does not exceed at full load 5% of 230V that is 11.5V.

for final circuits in particular for domestic installations ( mV/A/m) . L Ib
Power - 5% x 230V = 11.5V
Lighting - 3% x 230V = 6.9V .... 230V x 3% ÷ 100 = 6.9V etc .

Cooker circuit with ( Ib of 32A ) installed in conduit in an insulated wall . from 4D5A . ( T&E ) cable .
Method A* Colum 7 , a 6mm[SUP]2 [/SUP] cable is selected . from column 8 . this has a voltage drop ( per ampere per metre ) of 7.3 mV/A/m . if the length of cable is 10m then the voltage drop is :

(mV/A/m). L Ib / 1000 = (7.3) x 10 x 32 / 1000 = 2.3V . Q) is this less than 11.5V

 

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Learning curve only .

The effect of temperature upon conductor résistance

Copper has a positive coefficient . i.e. the warmer the cable the higher its résistance

The résistance tables for copper sizes are based upon an ambient temperature of 20°C and the résistance of copper cable increases by 0.004Ω per degree rise .

i.e. if a coil of cables temperature increases by 5°C , the corresponding increase in résistance will be 0.02Ω ( i.e. 5 x 0.004)

Value of résistance / metre for PVC insulated copper conductors and of ( R[SUP]1[/SUP] + R[SUP]2 [/SUP] ) per metre at 20°C in milli-ohms / metre .
GN-3 table B1 .
O.S.G. table 11 .

Where the résistance of a cable is measured at an ambient temperature other than of 20°C and the length is required, a correction factor must be used.
it must be ensured that when the circuit length etc. needs to be obtained, the values used in the calculations must be at the same temperature, i.e. either

Change the values in the résistance table at 20°C to whatever temperature the résistance measurement was taken at ( 5°C / 10 / 15 / 20 / 30 / 35 / 40°C )
GN-3 table B2 . goes up to . 5°C / 10 / 15 / 20 / 30 / 35 / 40°C
O.S.G. table 12 . goes up to . 5°C / 10 / 15 / 20 / 25°C

What does not change with the increase in temperature is its length .
Consider the 1mm[SUP]2[/SUP] cable . ( 20°C / 100m ) ◄

O.S.G. table 11 . The résistance for 1mm[SUP]2[/SUP] PVC insulated copper conductors at 20°C is 18.10 mΩ / m .
(∴) the total résistance of the cable 100 x 18.10 / 1000 = 1.81Ω
O.S.G. table 12 . the résistance / metre for 1mm PVC insulated copper conductors at 25°C is 18.10 mΩ / m x 1.02

(∴) résistance of the cable at 25°C = 100 x 18.10 x 1.02 / 1000 = 1.846Ω

O.S.G. table 12 .. Expected ambient temperature (°C) followed by , Correction factor ( applied to 20°C table )

if I loose the symbol (∴) therefore .

 

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BS-7671:2008(2015) :icon_bs:

There are now ( 20 ) Special Installations or Locations .

Q) Where will we use the IP code , The answer’s lies in BS-7671:2008(2015)
Requirements for Electrical Installations

Example Only .
Part 7 . Special installations or locations .
P/236 - 709.553.1.13. (( 709 / 553 / 1.13 ))
709 ) Marinas and similar locations etc.
553) This bit refers to the section in Part 5 ( 553 ) Accessories .
1.13) And this is the regulation, or series , regarding Plugs & Socket-outlets

Section 700 General .

The higher the IP rating the more protected the light will be.

Section 701 Locations containing a bath or shower
“ Zonal ” concept is based on the perceived risk of electric shock . ( 0, 1, 2, ) in relation to areas in / around the bath .
Having established the zones, particular requirements are then prescribed for:
switchgear
controlgear
accessories
current using equipment .

IPX7 , IPX4

Section 702 Swimming pools and other basins
702.512.2 - Electrical equipment shall have at least the following degree of protection according to BS-EN-60529:
IPX8 , IPX5 , IPX4 , IPX2 .

Section 703 Rooms and cabins containing sauna heaters
IPX5 , IPX4 .

Section 704 Construction and demolition site installations
Section 705 Agricultural and horticultural premises - IPXXD or IP44
Section 706 Conducting locations with restricted movement
Section 708 Electrical installation in caravan / camping parks and similar locations - IPX4 or IP3X
Section 709 Marinas and similar locations - IPX6 , IPX5 , IPX4 .
Section 710 Medial locations
Section 711 Exhibitions, shows and stands - IPXXD or IP4X .
Section 712 Solar photovoltaic (pv) power supply system
Section 714 Outdoor lighting installations - IP33
Section 715 Extra-low voltage lighting installations
Section 717 Mobile or transportable units - IP55 , IP44.
Section 721 Electrical installations in caravans and motor caravans - IP44
Section 722 Electric vehicle charging installations - IP44
Section 729 Operating and maintenance gangways
Section 740 Temporary electrical installations for structures, amusement devices and booths ............ IPXXD or IP4X
Section 753 Floor and ceiling heating systems - IPX1 , IPX7

IPX1. This will protect a device from some water drops that are falling vertically.

 

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Learning curve only . You have to study it yourself . ( IP Codes ) :book:

The two most popular used IP codes in BS-7671: are - IP2X / IP4X

The IP code is one method of checking to see if equipment is suitable for any particular area of risk.

(A3):2015 - Appendix 1 (Normative)

P/305 (A3) . BS-EN-60529:1992(2004) + A2:2013 .
Specification for degrees of protection provided by enclosures (IP code)

Index of protection is a code which gives us a means of specifying the suitability of equipment for the environmental conditions in which it will be Used .
527.2.3(i) & (ii) . 702.512.2 708.512.2(i) & (ii) . 708.55.1.8. A721.55.6. A721.55.10.

Basic protection
Barriers and enclosures are used to prevent contact with “ live parts ”
BS-7671:2008(2015) 416.2.2.
requires that readily accessible horizontal top surfaces of barriers and/or enclosures provide a degree of protection of at least IP4X or IPXXD

No access to live parts
BS-7671:2008(2015) 416.2.4.
Also requires that “ live parts ” shall be inside enclosures or behind barriers providing a degree of protection of at least IP2X or IPXXB

(iii) Where removal of a intermediate barrier providing a degree of protection of at least IPXXB or IP2X prevents contact with “ live parts ” by the use of a key or tool to remove the intermediate barrier.

For IPXXB
Full penetration of the British Standard test finger to a maximum of 80mm, the test is the same as that stated in IP2X and the finger must not come into contact with hazardous parts to comply to this requirement

If the installation passes IPXXB then it also passes IP2X

Degrees of Protection Provided by Enclosures (IP Code)
Document Number : BS EN 60529
Publication Date : 1992:

Gives uniformity in methods of describing the protection provided by enclosures and in tests to prove various degrees of protection. Provides an optional extension of the IP code by an additional letter A-D, if the actual protection of persons against access to hazardous parts is higher than that indicated by the first characteristic numeral.

Occasionally, you will see an IP code with an extra letter on the end: this is optional, and stands for ' other protections '.

Enhanced protection
IPXXA - 50mm sphere pressed against all openings to prevent ( Touching live parts with back of hand )
IPXXB - 12mm test finger and 80mm in length to prevent ( Touching live parts with a finger )
IPXXC - Access by probe 2.5mm diameter and 100m in length to prevent ( Touching live parts with a tool )
IPXXD - Access by probe 1mm diameter and 100m in length to prevent ( Touching live parts with a wire )

IP Codes for Beginners

IP rating details

Solid particle protection
0 - no protection at all
1 - Protects against objects larger than 50mm, like a fist - but if you put a little effort into touching the item in question, you won't be protected
2 - Protection against objects larger than 12.5mm like fingers
3 - Protection against objects larger than 2.5mm like tools, thick wires or your keys
4 - Protection against objects larger than 1mm, which includes most wires, screws, and anything else you may try to poke into the machine
5 - Dust protected: this provides complete protection against contact, and also prevents dust entering in quantities large enough to cause problems
6 - Dust tight: even the finest dust will give up in disgust.

 

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Learning curve only . You have to study it yourself . ( IP Codes ) :book:

Liquid ingress protection
0 - No protection
1 - Vertically falling water drips will not harm the equipment (equivalent to 1mm of rainfall per minute)
2 - Vertically falling water drips will not harm the equipment if it's tilted at an angle up to 15° (equivalent to 3mm of rainfall per minute)
3 - Protected against drops of water falling at up to 60° from the vertical
4 - Protection against spraying water at a pressure of 80-100kPa
5 - Protection against splashing water at the same pressure
6 - Protection against powerful jets of water
7 - Protection against water ingress when the object is immersed in up to one metre of water
8 - Protection against water ingress when the object is immersed in more than one metre of waterProtection against spraying water at a pressure of 80-100kPa

The 'other protection'
Letters A-D detail specific items that cannot penetrate an item. The final four letters simply give a little more information about the test conditions that led to the IP rating assigned.
A - Back of hand
B - Finger
C - Tool
D - Wire
H - High-voltage device
M - Device moving during water test
S - Device standing still during water test
W - Weather conditions

Example: 100A 20 way plastic consumer unit . ( obsolete now )
Top wall removes easily to provide cable access and reseals to IP4X

These ratings are determined by specific tests. Sometimes you will see IPX4 or IP4X. The (x) is used when the corresponding number is not required. For example: IP2X (the industry standard finger test) denotes that you cannot touch or gain access to live parts with your finger.

 

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My own take . Short. version
IPXXB, is the IP code for the degree of protection that must be provided once the cover is off a distribution board or consumer unit.

IP2X is the level of protection with cover in place .
IPXXB is with cover removed .

 

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O.S.G.

2008:
2011:

10.2.2. With the supply connected
vi ) check polarity of supply, using an approved voltage indicator .

(A3) 2015 10.2.2. (With) the supply connected and energised .
GS-38 (f) check polarity of supply, using an approved voltage indicator

 

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C&Gs - Level 3 Award in the Initial Verification of Electrical Installations (2394) February ( 2014 ) ◄ :svengo:

Leaning outcome

The leaner will:

6. understand the requirements for testing energised installations.
6.1 State the procedures for confirming polarity of the incoming supply. ◄

Re-cap .
Polarity is correct at the intake position @ consumer unit or distribution board ... Confirmation of supply polarity [✓]

Polarity .. two-methods
Dead testing . (Continuity method)
Live testing . an approved voltage indicator or test lamp

-&-s . Identify the test that should be applied to verify polarity after the supply is energised
Test to verify correct polarity of the incoming ( live-supply ) ............. test made at the Origin

O.S.G. (2015) P/105. Polarity
GS-38 . After connection of the supply, correct polarity must be confirmed using an approved voltage indicator or test lamp
( in either case with leads complying with the recommendations of HSE Guidance Note GS-38 )

Past tense ( check the dates )

GN-3 check polarity using an approved indictor
2008: P/46 2.7.11. ..... Polarity
After connection of the supply, polarity should be confirmed using an approved voltage indicator ( test made at the Origin )

► 2011: P/47 2.7.12. ..... Polarity testing
The polarity of all circuits must be verified before connection to the supply .

► 2015: 2.6.13. ..... Polarity testing
The polarity of all circuits must be verified before connection to the supply . refer

GN-3 referring too . Polarity testing
Alternatively. polarity can be verified by visually checking core colours at terminations thus verifying the installer’s connection. Whatever method is used, polarity checks are required at all points on a circuit.

Certification and Reporting

P/414 .. Electrical Installation Certificate (EIC)
Confirmation of supply polarity [✓]

P/424 .. Electrical Installation Condition Report (EICR)
Confirmation of supply polarity [✓]

P/417 .. Minor Electrical Installation Work Certificate (MEIWC)
Polarity satisfactory [✓]

( Point to note here )
Supply is connected .. Polarity “ Confirmation”

You will see that BS-7671:2008(2015) Regulations & Standards as the document against which a professional judgement needs to be made. ( That is why the wording changed in ( 2015) Skilled person ( electrically)

Q) Does the R1 + R2 test confirm the correct polarity of a radial circuit .
No, not on its own. Whilst the test can provide an indication of polarity, it needs to be combined with inspection and further testing as required by Part 6 of BS-7671: 2008:

Regulations . it comes under the heading off - Initial Verification ... 611.3. 612.6.




[/SIZE]

 

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One of the simplest of question’s -&-s ask you .

State :
the maximum rating of the RCD. the maximum disconnection time and the applied test current as required by Regulation 415.1.1, in BS-7671:20082015)

- Maximum rating 30mA
- Maximum disconnection time 40mS
- Maximum test current up to five times the maximum rating. i.e. 30mA x 5 = 150mA

The Regulations have to state the facts .

415.1.1
The use of RCDs with a rated residual operating current (IΔn) not exceeding 30mA and an operating time not exceeding 40mS at a residual current of 5 IΔn is recognized in a.c. systems as additional protection in the event of the provision for basic protection and/or the provision for fault protection or carelessness by users .

 

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re-cap .

RCDs used in BS-7671:20082015)
Typical uses and maximum ratings for residual current devices

► 30mA - final circuits supplying socket outlets on agricultural premises.
► 100mA - final circuits for socket-outlets in excess of 32A on agricultural and horticultural premises
► 300mA - protection against fire .
► 500mA - final circuits for socket-outlets in excess of 32A on construction site. P/223 .

Section 705
705.411. Protective measure: Automatic disconnection of supply .... ( ADS)

705.411.1. General
In circuits, whatever the type of earthing system, the following disconnection devices shall be provided:
(i) In final circuits supplying socket-outlets with rated current not exceeding 32A, an RCD having the characteristics specified in Regulation 415.1.1.
(ii) In final circuits supplying socket-outlets with rated current more than exceeding 32A, an RCD with a rated residual operating current not exceeding 100mA .
(iii) In all other circuits, RCDs with a rated residual operating current not exceeding 300mA .

 

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RCDs

Additional Protection.

Additional protection by Residual current devices .
The use of an RCD whose rating (IΔn) does not exceed 30mA and disconnects within 40mS when tested at 5 x IΔn is recognised as providing .

- Additional protection against the failure of basic protection .
- Additional protection against the failure of fault protection .
- Additional protection against carelessness by users .

415.1.1 :icon_bs:
The use of RCDs with a rated residual operating current (IΔn) not exceeding 30mA and an operating time not exceeding 40mS at a residual current of 5 IΔn is recognized in a.c. systems as additional protection in the event of the provision for basic protection and/or the provision for fault protection or carelessness by users .

 

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Change here . O.S.G.

O.S.G. 2.4.1. pre- 2011: ◄
Portable generator used with a floating earth . Small portable generators, ranging in output from 0.3kVA to 10kVA single-phase often have a floating earth .

O.S.G. 2.4.1. (A3 - 2015) ◄
Portable generator used with a floating earth . Small portable generators, ranging in output from 0.2kVA to 10kVA single-phase often have a floating earth .

refer us to . regulation . 551.4.4.

No change . 2008 / 2011 / 2015
Additional requirements for protection by automatic disconnection where the installation and generating set are not permanently fixed .

This regulation applies to portable generating sets and to generating sets which are intended to be moved to unspecified locations for temporary or short-term use . Such generating sets may be part of an installation which is subject to similar use . This regulation does not apply to permanent fixed installation’s.

Note: For suitable connection arrangements see BS-EN-60309 series.

 

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The importance in getting O.S.G. ( A3 2015)

Changes are made ( A1 2011 & A3 2015) :book:

O.S.G. pre-2011: ◄
7.2.5. Requirements for RCDs
RCDs are required:
411.5.
411.3.3. (i)
701.411.3.3.
411.3.3. (ii)
522.6.101
522.6.102
522.6.103
for cables without earthed metallic covering installed in walls or partitions with metal parts ( not including screws or nails) and not protected by earthed steel conduit or the like .

411.3.3. (b) i .
411.3.3. (a) ii .
(ii) socket-outlet circuits un situations where the use of equipment and work on the building fabric and electrical installation is controlled by skilled or instructed persons, for example, in some industrial and commercial locations; see 3.6.2.2.

O.S.G. 2015: ◄
7.2.5. Requirements for RCDs
RCDs are required:
411.5.
411.3.3. (i)
701.411.3.3.
411.3.3. (ii)
522.6.202.
522.6.203. (f)
for cables without earthed metallic covering installed in walls or partitions with metal parts ( not including screws or nails) and not protected by earthed steel conduit or the like .

(( Making you aware ))
Note: Metallic capping does not meet the requirements for (( mechanical protection )) as required by 522.6.204 . Metallic capping is used to protect the cables during the installation process and, once plastered over, does not provide any further protection .

Similarly, metallic capping would not meet the requirements for 522.6.204. (ii) or (ii) and would not satisfy the requirements of BS-7671: for a (( protective-conductor ))

A single layer of steel with a minimum thickness of 3mm is generally considered to provide sufficient mechanical protection against penetration by nails, screws and the like, except where short-fired nails are likely to be used.

411.3.3. (a)
specific labelled socket-outlets, for example, a socket-outlet for a freezer. However, the circuit cables must not require RCD protection as per (e) and (f) above, that is, circuit cables must be enclosed in earthed steel conduit or have an earthed metal sheath or be at a depth of at least 50mm in a wall or partition without metal parts.

411.3.3. (b)
In non-domestic premises, a documented risk assessment determines that the risk to users is sufficiently low for socket-outlets with a rated current not exceeding 20A .

2015: . as per (e) and (f) ................ 2011: as per (v) and (vi)

 

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Schedule of Inspections for the Electrical Installation Certificate :icon_bs:

The existing Schedule of Inspections for the Electrical Installation Certificate has been deleted. It is replaced by (a) and (b) below, one of which (as applicable) is to be used as the basis for the Schedule of Inspections to accompany the certificate.

(P/422) a. For installations in domestic and similar premises with up to 100A supply, a model schedule of inspections for new installation work in such premises.
b. For installations not covered by (a), a list of examples of items requiring inspection during initial verification of new installation work.

(a) and (b) contain a greater number of items than were included in the existing Schedule of Inspections (deleted by Amendment No. 3), many of which are quite detailed or particular. This gives (a) and (b) the advantage of being more like checklists. A few examples of items in (a) and/or (b) are:

1.0. items relating to the electrical intake equipment ;
such as the:
1.1. service cable
1.2. service head,
1.3. distributor’s earthing arrangement
1.5. metering equipment.

2.0. items relating to parallel or switched alternative sources of supply.

7.0. items relating to consumer units or distribution boards, such as:
7.1. adequacy of access and working space for items of electrical equipment including switchgear (132.12);
7.2. presence of linked main switch(s) (537.1.4, 537.1.5, 537.1.6);
7.4. suitability of enclosure(s) for IP and fire ratings (416.2, 421.1.6, 421.1.201); and
7.6. confirmation that all conductor connections are correctly located in terminals and are tight and secure.

8.0. items relating to circuits, such as:
8.1. adequacy of conductors for current-carrying capacity with regard to type and nature of the installation; ( Section 523)
8.3. segregation/separation of Band I (ELV) and Band II (LV) circuits, and electrical and non-electrical services (528);
8.4. cables correctly erected and supported throughout including escape routes, with protection against abrasion (521, 522); and
8.14. provision of additional protection by RCD not exceeding 30mA (with a list of possible applications).

 

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Some changes in ( A3 - 2015 ) :icon_bs:

(P/417) Minor Electrical Installation Works Certificate

In Part 3 ( Essential Tests ) of the Minor Electrical Installation Works Certificate, the fields for insulation résistance test readings to be inserted have been changed from [ Old 2011 - “ Line/earth ” and “ Neutral/earth ” ] Now (( to ‘ Live-Live ’ and ‘ Live-Earth ’ 2015 ))

Also in Part 3, the amount of detail required to be inserted in relation to the testing of an RCD has been increased, such that the operating time at 5 IΔn ( as well as at IΔn ) is included, as is confirmation that the test button of the device operates satisfactorily. ............. ✓

In Part 4 (Declaration), a field has been added for details to be recorded of any permitted exceptions to Regulation 411.3.3 relating to the omission of RCD protection to socket-outlets. As mentioned above in relation to the similar field in the Electrical Installation Certificate, this exception may be used only for an installation other than in a dwelling. Where the exception is used, a copy of the risk assessment must be attached to the certificate as required by Regulation 411.3.3.

 

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Some changes in ( A3 - 2015 )

Electrical Installation Condition Report

In Section D (Extent and limitations of inspection and testing) of the Electrical Installation Condition Report, text has been added to the effect that an inspection should be made within an accessible roof space where other electrical equipment is present.

Section J (Particulars of installation referred to in the report) now includes separate tick boxes for main bonding conductor connections to water installation pipes, gas installation pipes, oil installation pipes, structural steel, lightning protection and any other parts (as referred to in Regulation 411.3.1.2) to which such connections have been made.

In Section K (Observations), the column headed ‘Further investigation required (yes/no)’ has been deleted. However, it is still possible to state that further investigation is required in relation to an observation, by means of additional classification code, ‘FI (Further investigation required)’, which is now recognised in Section K.

Note 9 of the notes for the person producing the report has been revised with regard to where the inspection has revealed an apparent deficiency that could not be fully identified due to the extent or limitations of the inspection. The note points out that if a further investigation may reveal that the deficiency warrants the award of classification code C1 (Danger present) or C2 (Potentially dangerous), a recommendation of further investigation required (Code FI) should be recorded at Section K (Observations). It should be appreciated, however, that an FI classification should not be recorded if the investigation could only be expected to lead, at worst, to the award of C3 classification (Improvement recommended) in relation to the observation.

Notes 7 and 8 of the notes of guidance for recipients have been revised with regard to the person who undertakes any necessary remedial work in relation to a deficiency revealed by the inspection. Instead of referring to ‘a competent person’, the notes now refer to ‘a skilled person competent in electrical installation work’. The change has been made to the notes in order to describe more clearly the qualities that should be possessed by the person chosen to carry out such remedial work.

Note 9 of the notes of guidance for recipients has been revised for the same reason as Note 9 of the notes for the person producing the report, mentioned earlier; that is, in relation to further investigation.

Note 10 of the notes of guidance for recipients has been revised with regard to the person who undertakes re-inspection of the installation at appropriate intervals. Instead of referring to ‘a competent person’, the note now refers to ‘a skilled person competent in inspection and testing of electrical installations’. The change has been made in order to describe more clearly the qualities that should be possessed by the person chosen to carry out such periodic inspections.

Some additions and modifications have been made to the Condition Report Inspection Schedule Guidance for the Inspector, and to the Condition Report Inspection Schedule for Domestic and Similar Premises with up to 100 A Supply. The result is that these schedules, which are essentially checklists, are more comprehensive than they previously were.

In the Condition Report Inspection Schedule for Domestic and Similar Premises with up to 100 A Supply, the column headed ‘Further investigation required (yes/no)’ has been deleted. Also, the text in the schedule relating to the use of recommendation codes has been revised to take account of the introduction of the new Code FI (Further investigation required), mentioned earlier.