Consumer unit change - How do you do it?

[ChrisElectrical88]

That story’s awful. I take it that case had a massive baring on use of RCD protection.

 

[Dartlec]

In a domestic installation the equivalent would be a special box with hundreds of flyleads ending in magnets, that could be stuck onto every screw in the kitchen to provide a return path for the IR test. You saw it here first!

Don't give Megger ideas for the 1900 series!

Thinking aloud, would the use of a wander lead to do IR to any dodgy looking screw that caused concern show up all possible faults like this? I've never seen the use of a wander lead for IR testing, but only for R2 testing

It sounds like in the Emma Shaw case, the screw was probably plastered over and not accessible , and neither was the metal studwork - it was the pool of water that allowed the connection - so there were no potentially 'extraneous conductive' parts to test to.

 

[Pete999]

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?

I think it's safe to say an EICR should be recommended prior to a CU change, at the least testing should be carried out to prove tripping of the RECD does no occur on completion of the CU change, this will or should avoid any confrontation when the CU change is finished and the RCD trips, and you have to explain why everything has not gone as expected.
[automerge]1601735974[/automerge]

9.00 am. arrive on site.
9.30am. quick smoke and get tools off van.
10.00am. start stripping old CU.
12.00. break for 2 hour lunch at nearest pub.
14.30. screw CU on wall and start bunging in cables.
16.00. break for smoke and swig of JD.
17.00.bung lid on and throw main switch.
17.30. OK it works, pass go and collect £400.
18.00.park up at pub to spend some of the ill gotton gains.

you're right. a full day.

C

 

[telectrix]

I think it's safe to say an EICR should be recommended prior to a CU change, at the least testing should be carried out to prove tripping of the RECD does no occur on completion of the CU change, this will or should avoid any confrontation when the CU change is finished and the RCD trips, and you have to explain why everything has not gone as expected.
[automerge]1601735974[/automerge]

C

agree 100%. pete, you seen my post on the coronaviruskeeping it light. john bishop.

 

[Pete999]

9.00 am. arrive on site.
9.30am. quick smoke and get tools off van.
10.00am. start stripping old CU.
12.00. break for 2 hour lunch at nearest pub.
14.30. screw CU on wall and start bunging in cables.
16.00. break for smoke and swig of JD.
17.00.bung lid on and throw main switch.
17.30. OK it works, pass go and collect £400.
18.00.park up at pub to spend some of the ill gotton gains.

you're right. a full day.

Couldn't work like that, I would need to ensure everything is OK before going on the wee wee at the local, nice idea though.

 

[pc1966]

Thinking aloud, would the use of a wander lead to do IR to any dodgy looking screw that caused concern show up all possible faults like this? I've never seen the use of a wander lead for IR testing, but only for R2 testing

Doing a global IR test first (supply isolator off, L+N to E) would show most faults but not crossed circuits.

However, if an all-RCBO panel is fitted you will soon find out if they are!

But more seriously, if you want to check for all fault modes and you can have everything turned off / appliances disconnected then you could do this:

• Switch off input isolator, temporarily connect both L & N to E (using 10k resistors if you worry about no fusing and some muppet switching the supply back on).
• Disconnect each live (L, N) at a time and IR to the above shorted set. Say you test L1 then it shows any fault from L1 to {L2,L3...,MET,CPC1,CPC2,...,N1,N2...}
• Second wire, say L2, then shows L2 to {L3...,MET,CPC1,CPC2,...,N1,N2...} and, as you have already eliminated L1-L2, that is everything it could fault to.
• Repeat until all L & N are checked.

 

[Midwest]

Don't think I would of got many CU change jobs, if I insisted on my customer paying for an EICR first, at what a average cost of £150-300?

You can still factor in some pre testing before replacing the CU, you have to factor a reasonable amount into you quote.

 

[Pete999]

Don't think I would of got many CU change jobs, if I insisted on my customer paying for an EICR first, at what a average cost of £150-300?

You can still factor in some pre testing before replacing the CU, you have to factor a reasonable amount into you quote.

Then I think the ruling should be changed, to avoid the avoidable cases of unscrupulous, people quoting for CU changes without any testing beforehand.

 

[Midwest]

Then I think the ruling should be changed, to avoid the avoidable cases of unscrupulous, people quoting for CU changes without any testing beforehand.

What ruling?

I always tested first, before the old one came off. It doesn't make any business sense to say I'll charge a customer £200+ for an EICR, then £600-1200 (dependant on size of install etc) to actually replace the CU.

If its a very large property, then yes. But a two bed semi, you'd get shown the door.

 

[Pete999]

What ruling?

I always tested first, before the old one came off. It doesn't make any business sense to say I'll charge a customer £200+ for an EICR, then £600-1200 (dependant on size of install etc) to actually replace the CU.

If its a very large property, then yes. But a two bed semi, you'd get shown the door.

Then opinions need to change .don't they?