Re-take - Useful Information for 2394 :

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A Minor-Work-Electrical-Installation-Certificate does Not require details of

System earthing-arrangements
Departuresfrom BS-7671 :
Method of fault-protection
Prospective-fault-current

Which of the following is not a requirement of theinspection-checklist
Availability of the customer-user instructions
Presence of a BS-mark or othersuitable-certification
Correct selection of cable andprotection-devices
No-visible-damage

Oncean Electrical-Installation-Certificatehas been completed the original should be
Sent to the authority-building-control
Retained by the electrical-contractor
Given to the person ordering the work
Given to the tenant of the building

During the Inspection & testing sightwould indicate a fault such as
Overheating
Equipment-overheating
Vibration of transformer-cover
Damaged-equipment

Prospective-short-circuit-current is measured at the supply with main-earthing-conductor. ( PFC ) meaning , ( PSCC) or ( PEFC)
Connected to themain-earth-terminal
Connectedto the neutral-supply
Disconnectedfrom the main-earth-terminal
Connectedto the line-supply

Type- D BS-EN-60898 circuit-breaker should be installed to protect-circuitssubjected to ?
Overcurrents due to motor-starting
High-fault-currents
High-starting-currents
Low-inductive-currents

One of the following types of transformer only has one-winding , which-one ?
Voltage-transformer
Auto-transformer
Double-wound-transformer
Delta-transformer

What is increased when PV - modules are connected in parallel ?
Frequency-output
Voltage-output
Current-output
Light-output

What is the preferred-method of flushing outa New-central-heating-system ? By the use of a flushing-agent before start-up . Not - Electrical . Useful- Junk

 

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Earthing :

Earthing is the Connection of the “ Exposed-conductive-parts “ of aninstallation to the , main-earthing-terminal of the installation .

Metallic-parts of anelectrical-installation , exposed-conductive-parts . may become live when afault-occurs . these parts may be able to be touched .
The purpose of earthng is to direct a ,fault-current to earth , and cause the faulty-circuit ( in Question) to disconnect , preventing a currentfrom travelling directly-through a person and preventing a risk of fire fromthe faulty-circuit .

Exposed-conductive-part: Metallic-parts .
Cooker … ( Prone - to Earth-leakage-current )
Hob- being metal .
Washing-machine
Tumble-dryer
Freezer . Fridge … (Prone - to Earth-leakage-current )
Kettle . Etc

If a fault-occurs , the fault-current flows toearth . the protective-device-disconnects the fault , and prevents the , Metal-case of the cooker from being an Electric-shock-risk

Definition: p/27
Exposed-conductive-part : Conductive-part of equipment .

Which can be touched and which is Not-normally-live .
Which can become live-under-fault-conditions .

Definition: p/25
Class- 1 .
Equipment in which protection against electric-shock , does Not rely on basic-insulation only . but
Whichincludes , Means for the connection of, Exposed-conductive-parts , ( being- Metallic-parts ) to a Protective-conductor. in the fixed-wiring of theinstallation . Etc

Definition: p/32
Protective-conductor ( PE ) .
A conductor used for some-measures ofprotection against electric-shock , and intended for connecting together any the following-parts . Exposed-conductive-part(s)

Definition: p/32
Protective-earthing . ( PE )
Earthingof a point or points in a system . or aninstallation or , ( in equipment ) forthe purposes of safety .

Protective-device-disconnects the fault . ( in Question )
O.S.G.- 23 . Types of Protective-device .

RCBO- three- functions , Overload , Short-circuit , Earth-fault .
Overload-protection.

Miniature-circuit-breaker BS-3871-1 , type 1 . 2 . 3 . ( Obsolete ) still out - there ( Radically-different) characteristics . BS-
Circuit-breakers BS-EN-60898 , types B , C , D.
Residual-current-circuit-breaker(s) with integral-overcurrent-protection - ( RCBOs ) BS-EN-61009-1 . Part - 1 .
Fuses.

Definition: p/27
Earth-leakage-current: ( Protective-conductor-current )

Definition: p/32
Protective-conductor-current .
Electric-current appearing in a , protective-conductor, such as leakage-current or electric-current resulting from an insulation-fault .

 

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Point to Note :

BS-3871 : withdrawnin 1994
BS-EN-60898

Classified-according to theirinstantaneous-tripping-current . isgiven in O.S.G. - p/72 . where (In ) is the value of current that can becarried-indefinitely by the device .

Miniature-circuit-breaker

MCB / type - 1: instantaneous-trip-current - 2.7 to 4 x In .
Circuit-breaker / type - B : instantaneous-trip-current- 3 to 5 x In .
MCB / type -2 : instantaneous-trip-current- 4.0 to 7.0 x In .
Circuit-breaker / type - C : instantaneous-trip-current- 5 to 10 x In .
MCB / type - 3: instantaneous-trip-current - 7 to 10 x In .
MCB / type - 4: instantaneous-trip-current - 10 to 50 x In .
Circuit-breaker / type - D : instantaneous-trip-current- 10 to 20 x In .

Type - 1 & B , are the more-sensitive-devices .

 

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Overload : p/32

An Overload-current . An overcurrent occurring in a circuit which is electrically-sound :icon_bs:

All circuit(s) in the installationwill require-protection against , fault-current(s) but only those circuit(s) where an Overloadcan occur will require-overload-protection .

An Overload , is caused by a circuit carrying more current than that for which it was designed ,as the case of a , 3kW - load beingconnected to a circuit designed for 1kW, or a motor being overloaded-mechanically .

An Overload-occurs in a circuit which is healthy-circuit ,whereas a short-circuit is afault-condition , which occurs between live-conductor(s) in this case -includes the ( Neutral ) inconductor-connections . or in the equipment .

Live-conductors must be protected , by one or more devices for the , Automatic-interruption of the supply .in the event of an Overload , or fault-current . The devices must break anyoverload-current flowing in the circuit .

Relationship :

Symbols . p/38 . ( Ib)

The nominal-current rating of the protective-deviceis designated by ( In ) The design-current ( Full-load current of the circuit )
By ( Ib) and the current-carrying-capacity ofthe conductor(s) , by ( Iz ) The calculated-value of current-capacity-capacity required for the conductor is given , by ( It ) and the tabulated-current-carrying-capacity of the conductor / cable .

Symbols . p/38
( In ) rated-current or current-setting of protective-device .
( In must be Greater than or Equal to Ib )
The normal-current-rating or setting of the overload-device , must not begreater than the current-carrying-capacity of the smallest-conductor in thecircuit .

Symbols . p/38
( Iz ) current-carrying-capacity of acable for continuous-service under theparticular-installation-conditions-concerned
( Iz ) must be Greater than or Equal to ( In )

There is a further-requirement . that the current-causing theeffective-operation of the protective-device, referred to as , ( I[SUP]2[/SUP] ) must not exceed ( 1.45 ) times the , current-carrying-capacity of the smallest-conductor / cable in the circuit . ( I[SUP]2[/SUP] must not exceed 1.45- Iz )

Fusing-factor :
The factor -1.45 referred to in BS-7671: is thefusing-factor of the device obtained from the Equation . ( Fusing-factor = I[SUP]2 [/SUP]/ In ) Which is :
Fusing-factor = ( I[SUP]2[/SUP] ) Current-causing-effective-operation of the overload-protective-device “ on Overload / Nominal-rating of protective-device . ( In )

 

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GN-3. P/27

Note : Reference should also be made to therecommendations-contained in , Approved-Document - M . ( England & Wales ) &Scottish-Building-Standards with regardto the heights at which socket-outlets , switches and othercontrols should be installed .

IET publication Electricians’ Guide to the Building-Regulations .

 

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Re-cap . 2392-10 & 2394 . Initial-Verification : Meaning. Initial-Verification is carried outon a New-installation before it is put into service . GN-3 - p/15 What is Initial-Verification : 2392-10 2394 New-installation(s) Rewiring and extension Three-phase , !! O.S.G. p/11 . (ii) at a nominal-voltage of 230V a.c. single-phase or 400/230V a.c. three-phase . Construction , Design , Inspection & Testing . ( Phases ) to confirm that an electrical-installation complies with BS-7671:2008:2011: & is safe to be put into service . Initial-Verification : to confirm the installation has been , Designed & Constructed in compliance with the , British-Standards

- - - Updated - - -

Re-cap. 2392-10 & 2394 .

Initial-Verification: Meaning.

Initial-Verification is carried outon a New-installation before it is put into service . GN-3 - p/15

What is Initial-Verification : 2392-10 2394
New-installation(s)
Rewiring and extension
Three-phase , !! O.S.G. p/11 . (ii) at a nominal-voltage of 230V a.c. single-phase or 400/230V a.c. three-phase .
Construction, Design ,
Inspection & Testing . ( Phases ) to confirm that an electrical-installation complies with BS-7671:2008:2011: & is safe to be put into service .

Initial-Verification: to confirm the installation has been , Designed & Constructed in compliance with the , British-Standards

 

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ESC ) What action , if any , should be taken if it is discovered that the seal onthe DNO cut-out-fuse has been removed .

Theabsence of a seal is not an electrical safety issue and so no entry is requiredon the Condition Report. However, the owner/occupier should be informed thatthe seal is missing and they should be advised to contact the relevant DNO ormeter operator.

 

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Changes CoP 4[SUP]th[/SUP]Edition .

3[SUP]rd[/SUP]Edition was last printed in 2007 . itretained a restricted scope and the CoP were looking to broaden this scope . to include newer technology available to the Industry and a more modern way ofworking and the way Industry conducts itself .

Scopehas changed to include few-moreequipment types and premises anddifferent types of equipment and how they are used .

Second-hand-equipmenton the 3[SUP]rd[/SUP] Edition , being referred to as outside the scope of the CoP . however
4[SUP]th[/SUP] Edition Second-hand-equipment is in the scope . that is done inpurpose given the longer-life that appliances and equipment have duo to more stringent-manufacturing-processes .

CoP: couldn’t justify criminalising the sale ofsecond-hand-equipment that was still fitfor use and post no threats to safety toanyone and this adds equalramification in so much that the CoP wanted to promote some sustainability . second-hand-equipment is in the scope ofthe 4[SUP]th[/SUP]Edition .

Hireequipment wasn’t covered before . so much it needs to be understood if you hirea piece of equipment you areresponsibly for it after a certain-period . ( 7 days ) so it you hire a piece of equipment after seven-days , you are responsible for it maintenance and to insureits safe to use , and be used around people

Reclaiminghealth & Safety for all : November 2011.
An independent review of H&S legislation . Professor Ragnar E Lofstedt

Any inspection and testing ofelectrical-equipment is required to comply with the 4[SUP]th[/SUP]Edition IET code of practice for inService Inspection and Testing of Electrical-Equipment .
A recent government review on H&S legislation looked at howUK businesses were wasting money on “ Over Compliance “ andit was decided to revise the CoP .

PAT- Testing-Frequencies CoP - 7.1.
The general-consensus has been that PAT - testing needs tobe carried out every-year because of H&S &insurance-requirements . The new-revision-requires that the frequency of testing is based on a ( Risk- Assessment being carried out ) This would decide how often equipmentwould be tested-depending on the type of equipment .
Location and wear and tear .

PAT- Testing-Frequency ( Now . based on Risk - Assessment )
Fixed-equipment ( Not- portable ) Recommendations fortesting .
Class- 11 equipment . ( Not all require full Pat test) on your Risk - Assessment appliances’
Hireequipment ( Moreresponsibility on the hirer ) Water-cooler(s) & Vending-machine(s) Passes / Farecards. Etc
2[SUP]nd[/SUP] hand-goods ( Duty of care of seller )

Second-hand-shops. You must have a duty of care that thestuff your are selling is safe to Use .selling stuff on EBay & otherauction-sites selling on used electrical-goods its your reasonability tomake sure there safe . & when in use when selling them

Statement from , Associationof British-Insurers 2012 .
Directorof General-Insurance at the Associationof British-Insurers , ( Said )

Insurers have never required ( Policyholders to undertake unnecessary portable-electrical-appliance-tests which are not proportionate to the Risk )
We welcome HSEs guidance . which willhelp businesses-focus on what they do best free from worriesabout H&S myths .

 

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Main-Earthing-Terminal

The function of the (MET )is to provide a reference-point for the installation. it consists of aterminal or bar-providedfor the connection ofprotective-conductors . including protective-bonding-conductors . and conductors for functional-earthing .

Although the ( MET ) is connected to Earth . it is seldomat zero-potential because of the potential-difference caused by, leakage and other-currents flowing to earth . refer - 411.4.2.

411.4.2. p/54.
The neutral-point or the midpoint of the power-supply-system shall beearthed if a neutral-point or midpoint is not available or not“ accessible , a line-conductor shall be connected to Earth .

 

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2392-10 & 2394 . Re-cap .

State :

The human-senses that may need to beemployed during the . Initial-Verification of an Installation ???

During the initial-inspection it isimportant to use the following-senses .

Sight :
A visual-inspection is very-important since itcan pick up a large number of faults. ???
Labelling
Incorrect-cable or cable-size
Damaged-equipment
Incorrect-rotation of motors or equipment
Lights not functioning
Incorrect-protective-device-rating

Touch :
Touching-parts may show faults such as ???
Overheating
Loose-connections
Poor-fixings of such things as accessories
Unexpected-vibration of accessories or equipment

Smell :
The sense of smell may indicate ???
Equipment-overheating
Cables-overheating due to overload
Loose-connections causing-terminals to overheat

Hearing :
Sounds may indicate-problems such as ???
Unnecessary-arcing due to loose-connections
Vibration of transformer-cores
Poor-contactor-operation due todirt on pole-faces

 

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Basics.
State: the need for Instruments to beregularly checked and the need for compliance with the requirements ofBS-7671:2008:2011: and HSE Guidance-Note GS-38

All Instruments must be regularly checked toensure that they are . ???

Not-physically-damaged
Infull-working-order
Calibrated correctly and to date
Compliant with GS-38 with regards to test-leads, the main-requirements being .

Exposed-probe ideally no more than ( 2mm - 4mm maximum ) 2mm/ live-testing . 4mm / Dead-testing . ( Being a competent-person ) Etc
Finger-guards to stop-fingers slipping onto live-contact(s)
Test-leads or test-probes include-current-limiting . E.g. Fuse in test-lead(s)

Safe to Use .

 

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2392-10 . re-cap
• Defects or Omissions revealed duringinspection and testing shall be made good before the Certificate is issued . ( T ) 632.4 :icon_bs:
Defects or Omissions revealed during inspection and testing of theinstallation-work covered by the , Electrical-Installation-Certificate. shall be made good before the certificate is issued .

 

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Regulations. p/196

Re-cap 631.1.
Certification and Reporting . :icon_bs:

631.1.
Upon completion of the ( Verification of a new-installations or changes to an existing-installation ) an . Electrical-Installation-Certificate , based onthe model given in Appendix - 6 . shallbe provided . such documentation shallinclude details of the extent of the installation covered by the certificate , together with a record of theinspection . the results of testing and arecommendation for the interval until the first-periodic-inspection .

Electrical-Installation-Certificate: together with a schedule of inspections and a schedule of test-results , shall be given to the person-ordering the work .

The schedule of test-results shall identify every-circuit , including itsrelated-protective-device(s) and shall record the results of theappropriate-tests and measurements . 632.2. p/196

632.3. p/196
The person or person(s) responsible for the design , construction . inspection and testing of the installation shall provide the person ordering the work with a certificate that takes-account of their-responsibilities for the safety ofthat-installation , together with the schedules described in Regulation 632.1.

 

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Continuity of circuit-protective-conductors

Method 1 : Temporary-link
• Put atemporary-link between the , Line and CPC at the consumer-unit
• Continuity of Ring-Final-conductors
• Test for continuity at each-point in the circuit
• The highest-value recorded ( Usually at the farthest-point of thecircuit ) is the ( R[SUP]1[/SUP] + R[SUP]2[/SUP])

Method 2 : Wander-Lead
• Null the leads
• Connect one of the leads to the ( MET) Main-earthing-terminal
•Using a long-wander-lead-test for continuity of the , CPC at each point in the circuit
• The highest-value-recorded ( usually at the farthest-point of the circuit ) is the R[SUP]2 [/SUP]

Method 1 : determines the ( R[SUP]1[/SUP] + R[SUP]2[/SUP])
Method 2 : determines the ( R[SUP]2[/SUP] value )


- - - Updated - - -

Continuity of Ring-final-conductors

Step- 1 :
Measurethe end-to-end résistance of the
Line-loop ( r[SUP]1[/SUP] )
Neutral-loop ( r[SUP]n[/SUP] )
CPC-loop ( r[SUP]2[/SUP] )

Resistances should be same if conductors are thesame-size , the résistance of the circuit-protective-conductor will be higherif CPC is small-conductor ( x 1.67 for 2.5 / 1.5mm[SUP]2[/SUP] T&E )

Step- 2 :
• Connect the incoming-line with the outgoingNeutral for each-leg of the Ring .
• Take areading between the Line & Neutral at each-point within the Circuit .
• The value should be the same (within 0.05Ω ) withhigher-readings at any spur .

Expected-reading = ( r[SUP]1[/SUP] + r[SUP]n[/SUP] ÷ 4 )

Step- 3 :
• Connect the incoming-Line with theoutgoing Neutral for each-leg of theRing .
• Take a reading between the Line & CPC at each-point within the circuit .
• The values should be between ( within 0.05Ω ) with higher-readings at any spur .
• The highest-value is the ( R[SUP]1[/SUP] + R[SUP]2[/SUP])

 

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Periodic-Inspection & Testing . 621.2. p/195 :icon_bs: BS-7671:2008:2011

Periodic-inspection comprising a detailed-examination of the installation shall be carried out without-dismantling.
Note : theregulations do permit a certain-amount of “ Partial-dismantling “ if required.

• Safety of persons and livestock against the effects of electrical-shock and burns
• Protection against damage to property by fire and heat arising from an installation-defect
• Confirmation that the installation is not damaged or deteriorated so as to impair-safety
• The identification of installation-defects and departures from the requirements of these Regulations that may give rise to danger .