When a Consumer Unit Overheats/Burns Out etc....

[Clitheroe]

If this happens is it always a big nightmare job since if it is damaged severely on the inside or burntout it may not be just a case of fitting a new CU but also replacing all the cables running from it here there and everywhere round the house?

Just asking out of a matter of interest.

Sorry Imention replacing the cables since they will be damaged.

 

[333rocky333]

Not always, sometimes there can be enough spare on the cables under the floor or above the ceiling , to get enough good cable to reterminate.

 

[SparkyNinja]

Quite oftenly there will be a little slack there to pull, there's nothing we hate more than tought cables. If you manage to pull enough on all the cables, to re-make them off, consider yourself very fortunate.

Also if the wiring is in surface containment sometimes we can be cheeky and relocate the D.B. toward the direction of the wiring, I've managed that a few times.

 

[ban-all-sheds]

If this happens is it always a big nightmare job since if it is damaged severely on the inside or burntout it may not be just a case of fitting a new CU but also replacing all the cables running from it here there and everywhere round the house?

Just asking out of a matter of interest.

Wat a very odd thing to be asking about as a matter of interest.

Sorry Imention replacing the cables since they will be damaged.

You do realise that Schedule 2B 1(b) says "replacing a damaged cable for a single circuit only"?

Just asking out of interest....

 

[kwikfix328]

Does the reg stipulate a minimum time frame between deciding to replace each single 'damaged' circuit. One every 10 years , or one every 10 minutes - what's the difference...

 

[ban-all-sheds]

Were it to come to court, I'm pretty sure that common sense would prevail, and that if more than one circuit had damage and was replaced in what common sense would say was "at the same time", then the difference between 10 years and 10 minutes would be significant.

 

[Adam_151]

Another point that should perhaps be made here, is AFAIk the building regulations make allowance for emergency works for situations where notifying and giving 48 hours notice would be inappropiate, allowing the building notice to legitimatly be submitted after the work, same technical standards require apply of course

 

[Clitheroe]

Wat a very odd thing to be asking about as a matter of interest.

So what?

You do realise that Schedule 2B 1(b) says "replacing a damaged cable for a single circuit only"?
Just asking out of interest.... [/quote]

I was generally more interested about how difficult big a job electricians normally find this not about building regs etc. Same goes for everyone else going off the topic subject and going on about building regulations etc-it was not what I asked.

Thank you rocky and widdler for giving me a relevant answer I was actually looking for.

One reason I was asking about is before I fitted my current consumer unit, the previous one had overheated and started smoking, melting a tail on the RCD incomer and although it could have been much worse if a fire had occured and spread, the circuit cables in my house are run from the CU in sand/cement type walls in the sitting room!!!! just thinking imagine the cables had been burnt and HAD to be replaced....

 

[pompeygit]

Surely before replacing the consumer unit it would be a good idea to run a full set of tests on the existing cables to determine which if any need to be replaced. If the incomer to the rcd scorched it sounds like a L to N fault on maybe only 1 circuit. Simple IR testing would indicate which circuit is at fault. Replacing the consumer unit will not solve the problem alone. Perhaps others can allude to why the incomer overheated without without tripping the the circuit fuse/mcb. Other thoughts.......incomer to RCD incorrect size? Faulty RCD? Faulty MCB combined with too heavier a load? Bottom line a good periodic test would find the fault and allow you to sleep soundly

 

[plugwash]

if the incomer to the rcd scorched it sounds like a L to N fault on maybe only 1 circuit.

No it doesn't, If a circuit was drawing too much current and for some reason the breakers didn't trip I would expect damage to be primerally if not exclusively to the wiring of that circuit which is far lower rated than the incoming tails.

When you find heat damage centered on a single terminal a loose connection is by far the most likely culprit.

If a loose connection has a resistance of just 0.1 ohm and 50A (a fairly normal load for a house with a shower running) flows through the loose connection then you have 250W of power being dumped into a very small space.

 

[ban-all-sheds]

Wat a very odd thing to be asking about as a matter of interest.

So what?

So I thought it was odd, that's all.

I was generally more interested about how difficult big a job electricians normally find this not about building regs etc.

I wouldn't have thought you'd need the advice of electricians on how big a job it is to replace cables directly embedded into cement.

imagine the cables had been burnt and HAD to be replaced....

Yup. Major disruption and hacking away at walls. Blindingly obvious, really.

 

[Clitheroe]

OK just for everybody to know, what happened is one night in my parents house I saw the light flicker slightly in the sitting room with a hissing/buzzing sound coming from the CU. The next morning I got up and went into the shower, finished washing myself and was about to turn it off until it and the bathroom light went off themselves. My father came outside the bathroom saying the consumer unit had started smoking and had turned off the mains switch between the CU and meter.

The CU had was a second hand MK Sentry unit installed as a favour (by someone else, not me) seven years earlier for free. But since it had a poor install, old style MCBs, RCD mains switch 300ma and the neutral busbar had overheated at a previous time and we needed new circuits etc, the easiest and most sensible idea I thought was to replace the CU with a new one.