Two consumer units backfed

[mick b]

I have just come across a domestic installation that has two consumer units I was asked to wire extra sockets and do a board change as well. I found that the sockets of one board circuit are interconnected to a circuit from the other board, thus back feeding each other. This means that unless you isolate both boards or pull both relevant fuses then the whole installation remains live. I have wired my additional sockets to my own board , and explained to the client what the problem is. There is no way to find where these two circuits are interconnected without ripping up boards or going in loft and emptying it. And it's a possibility that it's been done more than once. Apart fron putting a warning notice for two sources of supply what am I meant to do. Mention of tearing the house apart was not well accepted.

 

[Dave OCD]

Just identify the two 'common' circuits and if it isn't a wrongly connected RFC get all cables together in one board and one MCB, obviously making sure the rating of the OCPD is correct for the circuit.

 

[mick b]

That's fine but if you put all the sockets in the house on a 20 amp breaker then it's asking for trouble. Thanks for replying without a small amount of sarcasm

 

[davesparks]

Ok then what do you do

What type of circuits are they? Presumably they are rings?

 

[mick b]

One ring one radial

 

[davesparks]

Why do I need a a report for an addition on my own board

the installation fails to meet a basic level of safety and you have knowingly left it in that condition, and carried out work on the installation and so will end up facing some tough questions if something goes wrong.

 

[mick b]

Exactly. But who is going to find a fault that until I arrived , no one knew existed , and will they let me turn off all the sockets in the house, or pay me to put right something that never existed until I turned up, on a never ending goose chase around the house

 

[Dave OCD]

One ring one radial

Are you certain that there isn't an end of the ring at each board ?

 

[mick b]

Yes. One is a Wylex board which was added 30 yrs ago and the old one is a old mem with 4 fuses from original wiring .

 

[mick b]

Just another bodge job when extended

 

[Octopus]

Why do I need a a report for an addition on my own board

Comments on the installation! Surely you realise what you noticed is potentially very dangerous.

 

[davesparks]

Exactly. But who is going to find a fault that until I arrived , no one knew existed , and will they let me turn off all the sockets in the house, or pay me to put right something that never existed until I turned up, on a never ending goose chase around the house

Why would you turn off all of the sockets in the house? Why would there be a never ending goose chase? Only incompetent idiots attempting to find faults will go on never ending goose chases.

If they are not happy to have the fault rectified the walk away and don't do any work. Carrying out alterations/extension/addition to the installation knowing that a very dangerous fault exists is negligence on your part.

 

[davesparks]

Just another bodge job when extended

Yes, another bodge job by someone ignoring a dangerous existing fault and just fitting another board so that they can pretend the existing installation isn't there and take the easiest route to getting paid.