C/U Change then Problems .............

[acvc]

Scenario: I was asked to replace a consumer unit in a house, rewireable to dual rcd. No previous problems. I did a visual inspection of the installation, did Zs'z on the rings, all was satisfactory. Changed the board, all circuits stable, and began to test. I've come across a break in the ring - no continuity on the end-to-ends.

Problem: the whole house (small victorian terrace) has the dreaded laminate flooring and the owners are not at all happy not at all happy not at all happy that I might have to get under their floors to find the break.

If the break is due to a wiring mistake then I can make to two 16A radials out of the mistake. If it's a mechanical break through the cable I should sort it out in case of exposed/extraneous conductive parts issues, although the stable rcds and mcbs would suggest this isn't the case.

1. Would you chaps be happy to go for the two 16A radials option?
2. Should I have done full tests on each circuit before I agreed to change it? As far is I know this is not required and I've never done this before.

 

[Mac]

Scenario: I was asked to replace a consumer unit in a house, rewireable to dual rcd. No previous problems. I did a visual inspection of the installation, did Zs'z on the rings, all was satisfactory. Changed the board, all circuits stable, and began to test. I've come across a break in the ring - no continuity on the end-to-ends.

Problem: the whole house (small victorian terrace) has the dreaded laminate flooring and the owners are not at all happy not at all happy not at all happy that I might have to get under their floors to find the break.

If the break is due to a wiring mistake then I can make to two 16A radials out of the mistake. If it's a mechanical break through the cable I should sort it out in case of exposed/extraneous conductive parts issues, although the stable rcds and mcbs would suggest this isn't the case.

1. Would you chaps be happy to go for the two 16A radials option?
2. Should I have done full tests on each circuit before I agreed to change it? As far is I know this is not required and I've never done this before.

I would have gone with No2 mate.You should have done a full test.Seem's you have opened a big can of worm's

 

[Graeme Harrold]

Ill vote no 2 too. even if its a change subject to a satisfactory periodic, as you would have to test it all anyway after the CU change. Should find the majority of your faulsy on visual and dead testing................

 

[kung]

Agreed knock power off and do dead tests before a change option mate saves hassle you can make 2 radials and split to find fault then if cant access faulty cable socket before discon outgoing socket after discon incomming unless as you say they arnt happy with up comes floor ! next time gadget next time !
Hope all goes well mate
Regards
Kung.

 

[sparks1234]

So, all you guys are saying that you do a full test on an installation before you agree to change a consumer unit then, and who pays for that if you decide you cant change it?

 

[kung]

All part of the prework survey i do as if you find something that the customer doesnt want to pay for you have the choice of walking before you get burnt and as said open a can of worms ! you dont need to do it but as it doesnt take long and it could save you a headache later. With who pays im affraid its just like a quote you might get it you might not better safe than sorry mate. and no i just do dead tests.
Regards
Kung.

 

[andekoch]

I tell the customer that the CU change is a job spread over 2 days. 1st to do a full PIR to check for faults and a second day to install the CU. I only start the 2nd day after discussing the results with the customer and make them aware that there may be other faults that become apparant when the CU is changed, like shared neutrals on landing lights that trip both RCD's when the light is switched on.
The quote then clearly shows the 2 items as separate and with a separate price for each so if after the PIR they decide not to carry on you get paid for the PIR only and all go home happy.

 

[electricAl]

So, all agreed that a more thorough test, prior to CU change is best. Lesson learnt, i`m sure for the OP.

However, i think he actually asked 2 questions, rather than 1 question with two possible answers...

As acvc`s mistake (it`s a real easy one too) is done now, it`s a case of damage limitation. Given the circumstances, splitting the ring in 2 doesn`t sound like it`ll bother the customer half as much as pulling their precious pad apart. Can`t think of a reason why you`d not do 2x 20A tho (other than it doesn`t divide into 32 quite so nicely!)

Exactly what problem did you have with the end to ends BTW? - somebody might be able to shed some light. (not me tho - i tend to light some shed
- well, i did a garden install today)

 

[sparks1234]

Agreed with installing the 2 no 20 amps and not 16 , the only slight hiccup is if the problem ends up being somewhere between the 1st and 2nd sockets and not half way

 

[shagg]

Why don't you disconnect all the sockets on the ring in question and bell them out to narrow the point of brack down if their is one? It could be a number of things. It could be two radials sharing one breaker as I'v seen this done in the past or it could be a spider of a radial with a spur off the CU breaker?

Sorry if i'm telling you how to suck eggs m8, just trying to help

what I normally do regarding the lost profit of a c/u change if somethings wrong is.

I tell the customer at the quote that I'll do a peridoic first to see if the circuits test out ok. And if they do I'll just charge for the c/u change as I'll have most of the test results for the cert.

And if it dose's I'll find what's wrong and charge for a peridoic. then they can choose where they go from there. Ever way I'll still get paid and they know the score .

It's a win/ win situation for both party's

 

[sparks1234]

Personnaly, I carry out a visual inspection of the obvious (bonding) and a look at the consumer unit to get a feel for its general condition. On my estimate i make it clear that there may be issues once the board has been changed, particularly now RCD's are being installed and consequently there may be issues to sort out, if they aren't happy with that then I would suggest they find someone else. Finding shared neautrals etc is not the quickest thing to find, particularly when you are basically doing it in a hurry for free.

 

[Graeme Harrold]

Personnaly, I carry out a visual inspection of the obvious (bonding) and a look at the consumer unit to get a feel for its general condition. On my estimate i make it clear that there may be issues once the board has been changed, particularly now RCD's are being installed and consequently there may be issues to sort out, if they aren't happy with that then I would suggest they find someone else. Finding shared neautrals etc is not the quickest thing to find, particularly when you are basically doing it in a hurry for free.

I feel this would put you in a difficult situation as you cant really issue an EIC for the CU change if the customer does not want to rectify faults found after the change. PIR up front would highlight all of this even if you only did the dead testing component subject to live tests after the CU change..............just my thoughts.............

 

[kung]

Agreed with installing the 2 no 20 amps and not 16 , the only slight hiccup is if the problem ends up being somewhere between the 1st and 2nd sockets and not half way

Then the customer has 3 options
1) Do away with that socket.
2) Run d-trunking for new feed to that socket (spur) or chase new feed if poss and keep as ring !
3) Up comes floor.
Id tell them its best to pull floor up or they can get a floorman as could be rodents etc and could damage more cables so best to find out exactly whats caused the fault !.
Regards
Kung.

 

[acvc]

OK It's me, the original poster of this thread. I returned to re-test again, just to be totally sure i was doing the right thing, and here's how it all panned out:

The old c/u 30A fuse had three single cores in it: one 2.5mm brown, two 2.5mm red.

The board had written on it that this way was "Sockets plus boiler".

So what would the averagely intelligence numpty like me (ok so I'm bigging myself up a bit) assume unquestionably?

Of course: that the new coloured (brown) core was the boiler.

Doh. The ring had been extended using new colours, and the boiler was spurred at the c/u from this socket circuit (in red).



I was very happy to take the humiliation from the client, very happy indeed given that their shiny new laminate flooring would remain intact.

But, I have learnt a big lesson here thanks to my stupidity and all your helpful posts: I need to improve my pre-c/u-change testing and inspection procedure. I will definitely be doing dead tests as part of it, and making it clear to the customer that it's a three part procedure:
1. inspect+test, and if no problems then
2. replace c/u and then
3. re-test and certificate.

Muchos gracias chaps.

 

[shagg]

Your welcome conpardray