Consumer unit change - How do you do it?

[catdog1121]

Dont change many consumer units, usually go ok but had one today that I did cheap for next door neighbour (Why is it always the ones you do cheap for friends and family that bite you). Anyway changed the board etc, all ok. Then came testing and obviously have various alterations in the last 40yrs, still had original wylex rewireable fuses.

I found Neutral ring missing - A socket had a neutral out.
Conservatory had two sockets, a light and an automatic window opener all spured off a spur in the kitchen with no grommets in the back box (Apparently done by an electrician)
One socket of two gang no neutral - just change face plate
One socket no neutral (Spur) - Just had to wago and put blank plate as obviously a junction box under the floor
There was some others as well.

Anyway in my haste to speed up testing I did insulation resistance with a couple of sockets off (I know stupid), when powered on RCD kept tripping if I removed socket neutrals it was fine. Finally tracked it down to a really tight socket in the kitchen that had a damaged neutral cable, managed to sort everything.

Started at 9.30, was running around in the dark finished about 8pm with everything ok, im totally shattered.

I am thinking of insisting on a full EICR before I do a consumer unit change again, at least you know what you are getting into mostly and you dont spend an entire evening trying to chase down issues as once you have changed the board and especially adding RCD's your kinda committed.

Just wondering do others do EICR beforehand or just wing it?

If you just wing it how often do you have issues?

 

[GBDamo]

If people are using 18v impact drivers to tighten down terminal screws something went wrong with the trade...

I'll be honest if I've got a board full I'll wizz all the terminals fully open with the driver and tighten them back up just tight enough to hold then run down the lot with the torque driver.

If you use an impact enough then you can be quite gentle with it.

Never rounded a screw yet

 

[Grant1987]

I'll be honest if I've got a board full I'll wizz all the terminals fully open with the driver and tighten them back up just tight enough to hold then run down the lot with the torque driver.

If you use an impact enough then you can be quite gentle with it.

Never rounded a screw yet

Ok so you’re under the category of experienced but I’m sure you agree with the fact that it’s more sensible to hand tighten terminations so you can feel the tension
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I don't regularly fit consumer units - in fact I've fitted a grand total of one and the use of power tools was limited to mounting it.

Good man stick to the hand tools once mounted ?

 

[GBDamo]

Ok so you’re under the category of experienced but I’m sure you agree with the fact that it’s more sensible to hand tighten terminations so you can feel the tension

There's a time and a place, if its an obsolete MCCB it'll be hand tools only, if its a board change and mistakes can rectified the returns outweigh the risk.

What does grind my gears is certain manufacturers applying thread lock to terminal screws, not sure how that helps come EICR time.

 

[Mike Johnson]

I don't know how these manufacturers calibrate their torque screwdrivers, but mine was so far out it could not be tightened to 2.1N required by Hager without bending the Din rail the RCBO was fixed too, anyone want to buy a full set of Armeg drivers?

 

[Grant1987]

I don't know how these manufacturers calibrate their torque screwdrivers, but mine was so far out it could not be tightened to 2.1N required by Hager without bending the Din rail the RCBO was fixed too, anyone want to buy a full set of Armeg drivers?

Normally it’s 1.7N isn’t it? Only 2.1 or higher for main switch you don’t need torque settings to know the correct torque I don’t think aslong as you understand the recommendations
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Normally it’s 1.7N isn’t it? Only 2.1 or higher for main switch you don’t need torque settings to know the correct torque I don’t think aslong as you understand the recommendations

Difficult area but again like I said it all boils down to experience and knowledge

 

[Mike Johnson]

None of Hagar's equipment is recommended to be torqued to as low as 1.7N, in fact it can be as high as 3.6N.

 

[pc1966]

What does grind my gears is certain manufacturers applying thread lock to terminal screws, not sure how that helps come EICR time.

It would depend on the type of threadlock.

Some is soft and easy to undo, only to stop gross loosening from vibration, etc. But some (e.g. "studlock") is like superglue and never expected to be undone without serious force!

If you do need to stop an adjuster from moving unintentionally and don't have anything special to hand you can use a dab of nail varnish, which you can get pretty much in any local chemist or supermarket.

 

[telectrix]

i have a small bottle of Loktite on the van. still half full after 20 years of occasiona luse.

 

[DPG]

It would depend on the type of threadlock.

Some is soft and easy to undo, only to stop gross loosening from vibration, etc. But some (e.g. "studlock") is like superglue and never expected to be undone without serious force!

If you do need to stop an adjuster from moving unintentionally and don't have anything special to hand you can use a dab of nail varnish, which you can get pretty much in any local chemist or supermarket.

It's a good excuse for why you're carrying nail varnish as well. I always carry women's tights as well in case my fan belt breaks.

 

[Zerax]

It's a good excuse for why you're carrying nail varnish as well. I always carry women's tights as well in case my fan belt breaks.

In case there are any woke snowflakes reading this... I should add that mens tights would work just as well.

 

[HappyHippyDad]

You should connect the cpcs first.

So when you test N-E for a particular circuit you will have all the CPC's connected in the earth bar? What would be wrong with doing the IR testing of N-E without having the CPC's in the earth bar? Are you saying parallel paths could cause different results? Are we not testing that particular circuit, i.e that particular cable, which is why we put the test result in the little box related to that one circuit?
A lot of questions there!

 

[ChrisElectrical88]

So when you test N-E for a particular circuit you will have all the CPC's connected in the earth bar? What would be wrong with doing the IR testing of N-E without having the CPC's in the earth bar? Are you saying parallel paths could cause different results? Are we not testing that particular circuit, i.e that particular cable, which is why we put the test result in the little box related to that one circuit?
A lot of questions there!

There could be Parallel paths to earth. I’ve never know anyone to not IR test with everything connected to the MET

 

[westward10]

See Regulation 643.3.1

 

[pc1966]

What would be wrong with doing the IR testing of N-E without having the CPC's in the earth bar?

The CPC of the circuit being tested is probably isolated from all the others CPCs and the Earth, so you would not see a leak from N to true Earth (e.g. a screw, etc, that is touching the N copper and in to plasterboard, etc) as it would not be guaranteed to complete the circuit from true Earth to CPC and back to your IR tester.
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Basic idea is this (sorry for poor diagram):

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So IR testing with the CPC isolated will pick up on an internal cable fault (say N to E), but not for external faults (N to some other CPC or true Earth).

 

[Dartlec]

See Regulation 643.3.1

Interesting - is that there to increase safety during the test and avoid 500V appearing on random metalwork for any length of time? Or is it to detect and test any parallel paths?

The CPC of the circuit being tested is probably isolated from all the others CPCs and the Earth, so you would not see a leak from N to true Earth (e.g. a screw, etc, that is touching the N copper and in to plasterboard, etc) as it would not be guaranteed to complete the circuit from true Earth to CPC and back to your IR tester.
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Basic idea is this (sorry for poor diagram):
View attachment 61176
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So IR testing with the CPC isolated will pick up on an internal cable fault (say N to E), but not for external faults (N to some other CPC or true Earth).

Interesting, I'd never really appreciated that. Though a screw piercing only N through plasterboard, would not be detected in any case would it? What would the viable parth to earth be for a screw, assuming it wasn't into a metal stud or in very wet plaster at time of test?

I guess it would pick up where the neutral for one circuit was damaged where it passed through the backbox of a different circuit or where rodent damage allowed the exposed neutral of a lighting circuit to touch cpc of a power circuit running alongside it in the loft.

I'll admit I've sometimes done the IR after first fix, mostly to check that plasterers haven't damaged a cable, and then not rechecked once connected.

On EICRS I usually do them with the cpcs connected, if only because it is sometimes hard to be sure which one is which anyway in a poorly installed board. (Though RFCs have to be located anyway of course)
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Just to add, I'm fairly sure on previous NICEIC inspections when they check my testing procedure (Usually a RFC continuity test, R1+R2 and then IR) they have never mentioned replacing the cpc before testing.

Obviously it's more to see the procedure than to actually do the test at that point, but maybe I'll get brownie points for ensuring I do at the next one - or he'll ask what I'm doing that for!