Commercial EICR - Your opinion?

[HomeCert ltd]

Hi All,

Being doing a commercial EICR over night (7-7) for the past week, still got a good few nights to go.

The installation is most likely 40-50 years old, was originally done well. About 5 years ago they had another contractor redo a lot of the electrics to accommodate the current owner. The previous electricains work is unreal, he has completely ruined the installation.

I'm not 100% sure how to approach this. There's a lot a minor things which need doing which I will report back, but the lighting in some of the areas is unreal. The previous contractor had used SY cable everywhere, not correctly terminated at any point, which I found out is carrying a healthy 157v on the braiding. Basically every earth has been cut out throughout the lighting, mainly class 2 fittings, but due to the fact a lot of he circuits are new and all the existing work has an earth, would that be a C2. As it should comply with when he installed it.

Also getting 287v back down a neutral when not connected via a circuit fed by a Seperate DB on the other side. Earths used as feeds in some cases, some lighting circuits supplied via 2/3 circuits, all with no CPC and low IR. Due to the fact it's suspended ceilings everywhere etc... I was thinking it might just be easy to just redo a lot of the lighting instead of trying to break it down and see what's salvageable.

What would any of you do?

 

[diditrain]

Submit your unsatisfactory report and get paid. Then discuss both options with the client.
If it`s as bad as you say, then it may take you as long and cost as much to rectify, than to rip it out and start again.

 

[Richard Burns]

You are doing the report at the moment so continue with that until complete but it maybe prudent to advise your client of the nature of the findings so far to prewarn them, but only provide full detail in the report or you may miss things and may be asked to stop the report.
The lighting is bad and the crossover of circuits is very worrying.
You state mainly class II fittings which means some are not class II so lack of earthing would be a C2 classification.
It may be easiest to keep light fittings and replace wiring runs but the layout of the circuits will determine the most appropriate method of rectification.

 

[westward10]

Concentrate on compiling a concise Report and using your judgement, suitably Code any issues. Do not fall into the trap of drifting to remedial solutions which will divert you from the task at hand.

 

[KEV 1 N]

It’s a shame when an old but perfectly useable installation is butchered by some body who doesn’t know and/or care what they are doing.
I’ve come across it all too often.....although nothing as bad as you describe.
Basically condemn it with C2 and FI comments where needed and as others have mentioned, worry about sorting it out later on when the report is completed.

 

[The Ghost]

I am puzzled. 157v on braiding? Is that not a real and immediate risk of electric shock? If so would it not warrant a C1. In which case the person ordering the work should be informed in writing and the inspection halted until that situation has been dealt with???

 

[Toneyz]

I take it this is where the old installation has been adapted by the electrician that installed the new lighting?

 

[westward10]

I am puzzled. 157v on braiding? Is that not a real and immediate risk of electric shock? If so would it not warrant a C1. In which case the person ordering the work should be informed in writing and the inspection halted until that situation has been dealt with???

Sounds a bit dramatic

 

[The Ghost]

Yeh might be a bit dramatic for you if you contact such voltage as well.

 

[westward10]

I meant halting the inspection. I am three quarters through an 800+ plus test and if I took this type of action I would be downing tools every hour.

 

[HomeCert ltd]

I agree, I wouldn't stop the inspection due to an issue like this. Simply make safe if possible or as I did, tape over the braiding which was exposed for the time being, with dozens of pictures etc... and note everything on report.

 

[HomeCert ltd]

Always good to know how others carry out their work, when doing an EICR would you simply test the IR on a DB as a whole. Did a 48 way board the other night, low IR with a 3 pole main switch, so went through one by one to identify one circuit which was low. But I remember when I was taught the guy who taught be said not to do that, record low IR for the board as a whole and then call for further investigation to identify any specific circuits.

 

[ipf]

Always good to know how others carry out their work, when doing an EICR would you simply test the IR on a DB as a whole. Did a 48 way board the other night, low IR with a 3 pole main switch, so went through one by one to identify one circuit which was low. But I remember when I was taught the guy who taught be said not to do that, record low IR for the board as a whole and then call for further investigation to identify any specific circuits.

I suppose it depends on different things.
What your quote or allows for.
Agreements made with the client beforehand.
Relationship with the client and what they expect.
Time scales, etc.
If it's not a quite recently installed job, without additions or alterations (in other words, a dream), it would be very unusual to be able to do a successful global IR test on such a board.

 

[ipf]

I suppose it depends on different things.
What your quote or allows for.
Agreements made with the client beforehand.
Relationship with the client and what they expect.
Time scales, etc.
If it's not a quite recently installed job, without additions or alterations (in other words, a dream), it would be very unusual to be able to do a successful global IR test on such a board.

If you could get extra time doing testing, which in my opinion, is part of the job anyway, good luck....but not my way....nor yours, I feel.

 

[westward10]

Rarely do a global IR as I generally work large commercial or industrial sites and from past experience it rarely pans out unless it is a few rudimentary circuits.

 

[ipf]

Rarely do a global IR as I generally work large commercial or industrial sites and from past experience it rarely pans out unless it is a few rudimentary circuits.

Exactly. Same here.

 

[Ian1981]

Most of the time if you do a global IR test on a 3 phase db then it’s gonna be less than 1Mohm so it’s pointless in my eyes.

 

[Ian1981]

Always good to know how others carry out their work, when doing an EICR would you simply test the IR on a DB as a whole. Did a 48 way board the other night, low IR with a 3 pole main switch, so went through one by one to identify one circuit which was low. But I remember when I was taught the guy who taught be said not to do that, record low IR for the board as a whole and then call for further investigation to identify any specific circuits.

I suppose if your IR reading for the whole board was 1Mohm or higher then it is acceptable but I would note it in the comments section

 

[Risteard]

Most of the time if you do a global IR test on a 3 phase db then it’s gonna be less than 1Mohm so it’s pointless in my eyes.

That problem won't disappear if you test them individually though as the requirement is for the insulation of the whole installation or DB to be above the values and not simply each circuit.

 

[Ian1981]

That problem won't disappear if you test them individually though as the requirement is for the insulation of the whole installation or DB to be above the values and not simply each circuit.

Just pointing out it’s in my opinion to test the circuits individually as the bigger the installation and circuit numbers then the lower the resistance in terms of going a global test

 

[Risteard]

Just pointing out it’s in my opinion to test the circuits individually as the bigger the installation and circuit numbers then the lower the resistance in terms of going a global test

The whole point is that it's lower though. BS7671 requires the installation/distribution circuit with final circuits connected to exceed the minimum values rather than individual circuits. Strictly speaking the quoted values are for initial verification though. No particular value for periodic insulation testing is mentioned.

 

[ipf]

That problem won't disappear if you test them individually though as the requirement is for the insulation of the whole installation or DB to be above the values and not simply each circuit.

A quick way of doing IR testing on a 48 way 3 phase board?....Global test below 1Mohm, C2, installation fail.
May get pay for an extra day or two on remedial work...on top of the initial quote, I suppose.
No wonder I get undercut.....

 

[Ian1981]

A quick way of doing IR testing on a 48 way 3 phase board?....Global test below 1Mohm, C2, installation fail.
May get pay for an extra day or two on remedial work...on top of the initial quote, I suppose.
No wonder I get undercut.....

Exactly!

 

[Ian1981]

The whole point is that it's lower though. BS7671 requires the installation/distribution circuit with final circuits connected to exceed the minimum values rather than individual circuits. Strictly speaking the quoted values are for initial verification though. No particular value for periodic insulation testing is mentioned.

I stick with 1 Mohm personally.
If the overall value is lower than this then I code it

 

[The Ghost]

I agree, I wouldn't stop the inspection

I meant halting the inspection.

It is a legal requirement EAWR and H&S. That is to make safe where dangerous conditions are found, with the agreement of the person ordering the work. Common sense should tell anyone if you find a dangerous situation such as a possibility of electrocution due to touch voltage being present at a hazardous level you would (?) rectify it??? or not. I certainly would out of consideration of the safety of others, hang the legal implications it is just horse sense.

 

[Risteard]

A quick way of doing IR testing on a 48 way 3 phase board?....Global test below 1Mohm, C2, installation fail.
May get pay for an extra day or two on remedial work...on top of the initial quote, I suppose.
No wonder I get undercut.....

Lets say that you measure 20 circuits at 10 Megohms each. The fact is these resistances are in parallel so would you wrongly consider that to be OK in spite of the fact that the requirement in BS7671 is for an installation/distribution circuit with all final circuits connected and not for any one circuit?

 

[Ian1981]

Lets say that you measure 20 circuits at 10 Megohms each. The fact is these resistances are in parallel so would you wrongly consider that to be OK in spite of the fact that the requirement in BS7671 is for an installation/distribution circuit with all final circuits connected and not for any one circuit?

That’s why we are tought the 1/Rt method of calculating the total resistance in parallel.
Scientific calculator at the ready

 

[Wilko]

I am puzzled. 157v on braiding? Is that not a real and immediate risk of electric shock? If so would it not warrant a C1. In which case the person ordering the work should be informed in writing and the inspection halted until that situation has been dealt with???

Hopefully this will be an induced voltage (if braid left floating say). Perhaps the 2 pole voltage tester will be helpful?

 

[The Ghost]

induced voltage

Indeed, I use a drummond with the two buttons that to check that out. I guess the OP has taken this into account?

 

[davesparks]

BS7671 requires the installation/distribution circuit with final circuits connected to exceed the minimum values rather than individual circuits.

Then why do the model forms provide individual boxes to record IR for each circuit? If they had intended us to measure and record global tests then surely the model forms would reflect this?

 

[Risteard]

Then why do the model forms provide individual boxes to record IR for each circuit? If they had intended us to measure and record global tests then surely the model forms would reflect this?

My understanding is that the boxes were intended to look nice. Hard to believe but apparently true. You could ask the same of the RCD test boxes. If the RCD is an RCCB it is likely to be protecting numerous circuits.

 

[Risteard]

That’s why we are tought the 1/Rt method of calculating the total resistance in parallel.
Scientific calculator at the ready

But that will give you an equally poor result than measuring the DB in parallel.

 

[davesparks]

My understanding is that the boxes were intended to look nice. Hard to believe but apparently true. You could ask the same of the RCD test boxes. If the RCD is an RCCB it is likely to be protecting numerous circuits.

But for RCBOs it is necessary to have individual results, which covers the majority of installations outside of domestics.
Where does this understanding come from because it is quite hard to believe?

 

[Ian1981]

The insulation resistance of a conductor is inversely proportional to its length that is, its insulation resistance decreases as the conductor’s length increases and vice versa. It follows that the insulation resistance of a complete electrical installation, or a section of it, will be less than that of a single circuit of that installation.
Global testing a large installation will mostly give you relatively low IR readings.
There’s no format to insulation resistance testing other than the overall resistance of the db circuits and any distribution circuit applicable to said DB is 1M ohm or greater.
The method you test it is down to the individual.

 

[DPG]

The insulation resistance of a conductor is inversely proportional to its length that is, its insulation resistance decreases as the conductor’s length increases and vice versa. .

To a point. But in practice, any length of new cable will have an IR of pretty much infinity, at least as far as any normal test equipment goes.

 

[Ian1981]

To a point. But in practice, any length of new cable will have an IR of pretty much infinity, at least as far as any normal test equipment goes.

It was more to do with carrying the test out during a eicr on larger 3 phase DBs.

 

[ipf]

Lets say that you measure 20 circuits at 10 Megohms each. The fact is these resistances are in parallel so would you wrongly consider that to be OK in spite of the fact that the requirement in BS7671 is for an installation/distribution circuit with all final circuits connected and not for any one circuit?

That depends on how far you want, or need in some instances, to break things down. As the thread indicates, 'your opinion'. There's an argument to every opinion... we can all pick straws.

 

[Risteard]

Where does this understanding come from because it is quite hard to believe?

From someone who was senior with the NICEIC at the time, as quoted on the IET forum on numerous occasions. (I don't know him personally.)