Re-take - Useful Information for 2394 :

[amberleaf]

I owe thisforum a hell of a lot . I’ve had more understanding of Inspection &Testing from this forum . & muchmore .
Yes at onetime I was a bit GREEN.

Dan & Jason gave me the chance to help other people & help myself in the process . So my payback is ( I am Loyal to the forum ) am not jumping ship . Electricians-Forum-Member. always 100% . No matter what hits the FAN .

Thank youDan & Jason for your Support over the Years .

 

[amberleaf]

Younger electrician on site working with a Megger -1552 . not sure of the ropes . some assistance was in order . we’re all singingfrom the same hymn-book here . Thisforum is here to HELP-ANYBODY that needs HELP . does not mater how SMALL .

Back tobasic . ( Nulling )

Continuity- Nulling out the leads . Megger - 1552.

Switchingon . ( set at Ω ) D.C.
> 99.9kΩ - Not nulled yet . ( yourequire . Stable-reading from the Shorted-leads before you hit the -yellow-button ) a few-seconds allow .

Leadstogether 0.14Ω - the Null-symbol will not shown yet .
Push theyellow-button . once and hold a few-seconds ◄ . ( 0.00 ) the Null-symbol will remain ON . start your test .

Your ( Backlight ) press the Black-button . & it will light up .

 

[amberleaf]

Some -facts .

p.39. GN-3. ( IR )
Insulation-résistance-testing. is a fundament-test for inspector(s) . Often on larger-construction-sites .cables will be ( Insulation-résistance-tested during various-stages ) of installationto ( Prove the integrity of the installed-cables ) it is always preferred to re-test-cable(s) andequipment for . Insulation-résistance as part of ( Initial-verification ) as well as ( During-construction )

Re-cap. p.40-GN-3 .
Simple-installation(s)that contain no-distribution-circuits should preferablybe tested as a ( Whole )

Re-cap. p.40-GN-3 .
To performthe test in a ( Complex-installation ) it may need to be ( Sub-divided into its component-parts )

Insulation-résistance.
( 2394: -point to note ) if a circuit is found tohave an ( IR ) of less than ( 2MΩ it should beinvestigated ) inGN-3.

Testing ofIndividual-circuit(s) . 2394: . you cant go wrong with this . for the sake of Exams . Safety-precautions must be taken .
If wewhere on site . each-circuit to beisolated-individually . ( Locking-OFF ) the circuit-breaker .

Only inextreme measures. Isolate the whole of the distribution-board .

Insulation-résistance. as a Whole-installation . we have Parallel -paths .
( Parallel -paths )Neutral-conductors or Circuit-protective-conductors . will be connected to acommon Neutral-bar and the Circuit-protective-conductors for all circuit(s)will be connected to ( MET ) Main-earthing-terminal .

To test Individual-circuit(s) we do not have ( Parallel -paths ) Domestic-installation .

Testing :Insulation-résistance . between allThree-conductors . Megger-1552 .settings - 250V . 500V .
Yourtesting at 500V . d.c.
Onexcising-circuits . sensitive-equipment - computers . voltage can damageequipment.

Test-betweenyour . Circuit-protective-conductor .and Line-conductor - Which is disconnected . > 500V MΩ
Test-betweenyour . Circuit-protective-conductor .and Neutral-conductor - Which is disconnected . > 500V MΩ
Test-betweenyour . Neutral-conductor . and Line-conductor - Which is disconnected . > 500V MΩ

17[SUP]th[/SUP]Edition BS-7671:2008:2011: reminds us. 500V - d.c. → → Minimum-insulation-résistance ( MΩ - 1.0MΩ )
When Idone my 2392-10 : I was taught to do ( IR ) Testing of Individual-cable(s) Line to Line . Neutral toNeutral . CPC to CPC.
&
Line to Neutral - together . plus Circuit-protective-conductor. Minimum-insulation-résistance ( MΩ - 1.0MΩ )

 

[amberleaf]

Absence of a earthing & bonding-label . will onlybe a C3 condition on the report -
Absence of Main-protective-bonding if required by theregulations . would be a C2 . as would absence theeffective-means of earthing .

( Thereason absence of means of Earthing. Is only C2 it in not immediate dangersuch as exposed-live-part ) Unsatisfactory .

3.0 . Earthingand bonding-arrangements - p.400
- Presenceand condition of distributors-earthing-arrangement . ( C2 )
- Presenceand condition of earth-electrode-connection . ( C2 )

-Confirmation of adequate earthing-conductor-size .
-Accessibility and condition ofearthing-conductor at . Main-earthing-terminal - ( MET ) ( C2 )
-Confirmation of adequate . main-protective-bonding-conductor-size . ( C2 )

-Confirmation of accessibility of .main-protective-bonding-conductor-connections .
-Provision of earthing and bonding-labels at all-appropriate-locations . ( C3 )

Firstly .33. Reporting - Communicating theresults of periodic-inspection &Testing of an electrical-installation to the person ( Ordering the work )

What isPeriodic-inspection & Testing .

p.399: The purpose of this - Condition-report is toconfirm . so far as reasonably-practicable . whether or not theelectrical-installation . is in a
satisfactory-conditionfor continued-service . the report should-identify any damage . deterioration .defects and / or conditions which may give rise to danger .

 

[amberleaf]

BS-7671: in itself . not-statutory-requirement but isprimarily a design-standard .

Requirements forElectrical-Installations BS-7671:2008:2011:
Introduction to BS-7671:2008: hasthe status of a British-Standard and relates . principally to the Design .Selection . Erection . Inspection and Testing . of electrical-installation(s)

Whilst not ( Statutory ) the Regulation represent whatis considered best-practice in these areas . there is a comment in theintroduction of both the
Electricity at Work Regulations -1989 and BS-7671: which states that compliance with BS-7671: is likely toachieve compliance with the relevant-aspects of the Electricity at WorkRegulations - 1989

This is why all reports should bein accordance with . Chapter 62 of BS-7671: so they can . if required . be used for a defense in the eventof an electrically-related-incident inthe workplace .

Electricity at Work Regulations -1989 . requires Inspection and Testing .

Electricity at Work Regulations -1989 . in Regulation 4(1) & 4(2) lay down the requirement to ensure that anElectrical0installation should be . design . installed . constructed andmaintained in a safe-manner at all times.

Electricity at Work Regulations .guidance-notes advice to Inspect and Test will satisfy the law and provide thedefense that the “ Duty-holder “ took all reasonable-steps and exercised alldue-diligence in order to avid committing an offence . Electricity at WorkRegulations - 1989 . Regulation - 29 .

Electricity at Work Regulations-1989 . ( Statutory )
17[SUP]th[/SUP] Edition 2008:2011 Non - Statutory )
Guidance-Note - 3 - ( Guidance )

If we look at the relationshipbetween the documents .

The introduction within the .Memorandum of Guidance on the Electricity at Work Regulations - 1989 . Statesthat “ Compliance with BS-7671: islikely to achieve compliance with the relevant aspects of the Electricity atWork Regulations .

GN-3 . Inspection & Testing .whilst providing good guidance . does state “ while the publisher andcontributors believe the information and guidance given in this work is correct. all parties must rely on their own skill and judgment when making use of it .( Effectively a disclaimer )

Regulation - 612.1.British-Standard .
States : That “ Where noprevious-documentation is available . Investigation of theelectrical-installation shall be undertaken prior to carrying out the (Periodic-inspection & Test )

Competence is a mix of thingswhich includes .

What makes a “ Competent-person“ Regulation - 16 of the Electricity at Work Regulations - 1989.States that “ No-person shall be engaged in any work-activity wheretechnical-knowledge or experience is necessary to prevent danger . Unless they possess such knowledge orexperience . or is under a degree of supervision as may be appropriate havingregard to the nature of the work .knowledge or experience of electrical-work . understanding the system beingworked-on . understanding all the hazards and precautions . and having theability to recognise danger and when it is safe to work .

 

[amberleaf]

Voltage-drop-calculations.

Thevoltage-drop in a cable-conductor(s) isdirectly-proportional to the . circuit-current and the length of the cable-run.

(Vd) Voltage-drop = [ current - ( A ) x length of run ( m ) xmillivolt-drop-per ( A/m ) 1000 ]

Divisionby 1000 to convert-millivolts to . volts .

p.130. 525 : Voltage-drop in Consumer’s - Installation(s) .

Note : BS-7671: requirement - 525.1. limits the voltage-drop permitted between the ( Origin of the supply ) and the load to ( 3% ) for lighting and 5% forall other circuit(s) . for a 230Vsingle-phase-supply this is 6.9V for - Lighting and 11.5V for other-circuit(s) .

Regulation- p194 : Note .Verification of voltage-drop is not-normally . requiredduring-initial-verification .

 

[Jurasic Spark]

Voltage-drop-calculations.

Thevoltage-drop in a cable-conductor(s) isdirectly-proportional to the . circuit-current and the length of the cable-run.

(Vd) Voltage-drop = [ current - ( A ) x length of run ( m ) xmillivolt-drop-per ( A/m ) 1000 ]

Divisionby 1000 to convert-millivolts to . volts .

p.130. 525 : Voltage-drop in Consumer’s - Installation(s) .

Note : BS-7671: requirement - 525.1. limits the voltage-drop permitted between the ( Origin of the supply ) and the load to ( 3% ) for lighting and 5% forall other circuit(s) . for a 230Vsingle-phase-supply this is 6.9V for - Lighting and 11.5V for other-circuit(s) .

Regulation- p194 : Note .Verification of voltage-drop is not-normally . requiredduring-initial-verification .

Whichever way you look at it, volt drop is simply Ohm's Law where:
V = I x R

 

[amberleaf]

Q ) . The prospective-short-circuit-currentat the Origin of the . consumer’s - installation must be taken into accountwhen .
A) . Selecting the type of .overcurrent-protective-device . to be installed .

Q ) . Design-calculations involving-conductor(s) and anovercurrent-protection-device . most likely satisfied when .
A ) . ( In ) is not less than .the design-current ( Ib )

Calculate - Actual ( Zs ) [ Zs = Ze + R[SUP]1[/SUP] + R[SUP]2 [/SUP] ] 0.23Ω + 0.6Ω = 0.83Ω . ( Zs ) = 0.83Ω
Calculate - Maximum-earth-fault-current . [ Uo /Zs = ( If ) ] 230V ÷ 0.83Ω = 277.1A
Formula : calculating .earth-loop-impedance . Zs = Ze + R[SUP]1[/SUP] + R[SUP]2 [/SUP] .

Multicore-cables.
The term “ Multicore “ is used to describe a cable wheretwo or more separately-insulated-conductors are contained within asingle-outer-sheath .

 

[Jurasic Spark]

Q ) . The prospective-short-circuit-currentat the Origin of the . consumer’s - installation must be taken into accountwhen .
A) . Selecting the type of .overcurrent-protective-device . to be installed .

Q ) . Design-calculations involving-conductor(s) and anovercurrent-protection-device . most likely satisfied when .
A ) . ( In ) is not less than .the design-current ( Ib )
Although this is true I think a better answer to that question would be In is not greater than the current carrying capacity of the cable it is protecting.

Calculate - Actual ( Zs ) [ Zs = Ze + R[SUP]1[/SUP] + R[SUP]2 [/SUP] ] 0.23Ω + 0.6Ω = 0.83Ω . ( Zs ) = 0.83Ω
Calculate - Maximum-earth-fault-current . [ Uo /Zs = ( If ) ] 230V ÷ 0.83Ω = 277.1A
Formula : calculating .earth-loop-impedance . Zs = Ze + R[SUP]1[/SUP] + R[SUP]2 [/SUP] .

Multicore-cables.
The term “ Multicore “ is used to describe a cable wheretwo or more separately-insulated-conductors are contained within asingle-outer-sheath .

......

 

[amberleaf]

Useful -junk .

p.77 . p.85 . Values of ( k ) for common-materials . for calculation of theeffects of . fault-current . for the disconnection-times up to ( 5 - seconds )

Regulation(s)Table - 43.1 . [ t = K[SUP]2[/SUP] S[SUP]2[/SUP] / I[SUP]2[/SUP] ]

Where:
t ) is the duration in seconds .
S ) is the C.S.A. of conductor in ( mm[SUP]2[/SUP] )
I ) is theeffective-fault-current . in amperes . expressed for . a.c. as the rms-value .due account being taken of the current-limiting-effect of the .circuit-impedance .
k ) is a factor taking account of the resistivity. temperature-coefficient and heat-capacity of the conductor-material . and theappropriate initial and final-temperatures . for ( Common-materials ) the values of ( k ) are shown in Table - 43.1. (K[SUP]1[/SUP] )

70°C . ( Ief ) - 200A . ( t - 2 seconds ) . by calculation . 200A x[SUP]2[/SUP] x 2(t) =80. ( press on the calculator ( √ = ) then it will show . 282.8427125 ÷ ( k[SUP]1[/SUP] - 115 ) = 2.4mm[SUP]2 [/SUP]

Thermoplastic.
70°C ≤ 300mm[SUP]2 [/SUP]“ Under “ ◄◄ . Copper-conductor - ( k ) 115 . “ Under “
70°C > 300mm[SUP]2 [/SUP]“ Over “

 

[nexlar]

We want you to be totally happy with our phone and broadband services – even the things that are beyond our control. So we’ve compiled a list of information we think you may find useful.

 

[SLSpark]

Looking for info on 2391 testing & inspection course anyone help ?

 

[amberleaf]

Q) . An electrical-installation-certificate should be signed by .
A) . Competent-person . ( this Question. has Answered the other two - Q/As ) -&-s will fling at you .

Appendix- 6 . informative . p.389 .
Electrical-Installation-Certificate. required by part - 6 . should be made out and signed or otherwiseauthenticated by a ( Competent-person ) or person or persons in respect of the design. Etc . ( i ) ( ii ) ( iii )
(( i ) EIC ) . (( ii ) MWC ) . (( iii ) EICR )

(iv)Competent-person will . as appropriate totheir ( Function-under ) ( i ) (ii ) ( iii ) above . have asound-knowledge and experience-relevant to the nature of the work-undertakenand to the . technical-standardsset down in these Regulation(s) .
2394:- Be fully versed in the . Inspection &Testing-procedures . contained in the Regulation(s) & ( Employ-adequate-testing-equipment )

 

[amberleaf]

RCDs
Shouldbe tested at . 50% . 100% . 500% .
RCD- providing-additional-protection of their rated-residual-operating-current ( IΔn ) . 500% . x5 .

Wherean RCD is employed to achieve the . disconnection-time required by Table -41.1. it is necessary to confirm thatthe maximum-earth-fault-loop-impedance (Zs ) stated for a . particular sensitivity of the RCD in . Table - 41.5. are not exceeded in thecircuit to which they protection .

 

[amberleaf]

Protective-device(s) is used to ( Achieve the disconnection-time(s) required by table -41.1. whether Fuse . Circuit-breaker . or RCD . To confirm that the required-disconnection-time can be achieved by (Testing the protective-device ) We confirm that the . earth-fault-loop-impedance. of the protected-circuit doesnot-exceed the relevant-tabulated-maximum-earth-fault-loop-impedance for thetype . ( of protective-device we areusing )