Domestic DIY Very Big Bang

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I am not a professional electrician and am posting this partly for your general amusement and partly to get some background advice.

My son who has recently moved into a rented flat in Nottingham having got his first job there, decided to put up some coat hooks. He seems to have taken insufficient notice of the fact that the consumer unit is above where he was drilling. Apparently there was a very big bang and the hole shown in the picture appeared without any further exploration on his part.

He phoned me for advice and sent me the pictures, mentioning that none of the fuses seemed to have blown and everything is still working. I explained that the reason no breakers had tripped was that these are the main cables coming into his consumer unit and therefore before his breakers. I am a bit surprised that the company fuse didn't blow, but I guess it must have been a very short bang.

My advice was call your landlord's agent, you need an electrician because there is no way you should attempt to do anything with this.

The consumer unit is near the ceiling on the opposite side of the wall to the meter cupboard.

My questions are first will there be any way to fix this other than digging out the cables and replacing them from the meter to the consumer unit.

Secondly to ward against the agent inflating the cost, what sort of ball park cost should it be.

Finally, is it appropriate for the main cables to be buried in the wall without any protection (from idiots).
 

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Strima

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Those tails will need to be dug out and replaced. They will also need either RCD protection at the meter side or mechanical protection to prevent this from happening again.

Ideally the tails should be routed to negate the need for an RCD. It's going to cost him a few quid...

Send him this link: https://lmgtfy.com/?q=safe+zones+for+cables
 

Dobes_88

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There should be RCD protection on those tails as they're buried <50mm without mechanical protection.

The only way unfortunately would be to dig it out to inspect further and potentially replace...

Looking at it the left hand side earth cable (looks like a 10mm from picture) could be connected to the gas or water pipes, arcing could potentially bring the pipes up to 240v - would advise to get someone out to at least have a closer look.
 
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ferg

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I might go as far as suggesting getting someone out to that tonight.

You wouldn't want that sitting around being live and it may not take much for the fault to start arcing.
 
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  • #5
How long ago would regs requiring RCD or physical protection have come into force.
 
D

Deleted member 9648

You should not permit anyone to install an RCD on the supply side of the tails, it is likely your son will be plagued by nuisance tripping with total loss of power each time. This is would be a departure from Bs7671.The best option is to run new tails and earthing conductors in surface trunking which will remove the need for RCD protection on the supply side.
 

Paignton pete

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How long ago would regs requiring RCD or physical protection have come into force.
Hopefully some one will come along and confirm or correct this, but I think it was the 2013 reg changes or was it the 2011 to have cables buried 50 mm deep or have additional protection.

Sorry I was absolutely no help whatsoever ever there.
 

James

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I would get someone out to replace the tails, however I am disappointed to see no capping over the cables to protect them from the plaster.
 

GBDamo

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Be nice to see the damage in relation to the consumer unit.

Are they directly below? Is there any mechanical protection.

If not id be trying my hand at claiming its not correctly installed and look to dodge the bill.

Oh and pass on my congratulations, damn fine shot that.
 

James

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Be nice to see the damage in relation to the consumer unit.

Are they directly below? Is there any mechanical protection.

If not id be trying my hand at claiming its not correctly installed and look to dodge the bill.

Oh and pass on my congratulations, damn fine shot that.
2mm to the right and you would have a live coat hook installed for the mother in law!!!
 

DPG

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however I am disappointed to see no capping over the cables to protect them from the plaster.
Pretty insignificant compared to the fact that there are live tails directly under the plaster with no protection though!
 
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  • #13
Be nice to see the damage in relation to the consumer unit.
Hmmm, considering my son is an engineering graduate, it does look rather like he was trying for a Darwin Award.

Is there any mechanical protection.

If not id be trying my hand at claiming its not correctly installed and look to dodge the bill.
It looks clear to me there is no mechanical protection.

The building is probably 1960s or 70s I don't know when the electrical instalation dates from. But if there should have been mechanical protection then that might help reduce his bill.
 

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GBDamo

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Not much wiggle room there to ne honest, other than mechanical protection, the cables are where you'd expect them to be.

Might be worth confiscating his DIY toys until he can prove hes not suicidal
 

ferg

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I have to agree with GBDamo those cables are exactly where you would expect cables to be.

It should also be said he's a very lucky boy.
 

davesparks

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Finally, is it appropriate for the main cables to be buried in the wall without any protection (from idiots).
Looking at the likely age of the installation I woukd say its likely that it was permitted for those cables to be buried like that with no further protection according to the regulations at the time.

However the current regulations do not permit this so the replacement cables will need to have mechanical protection installed. Whoever carries out the replacement will have to work to the current regulations so will need to Chad eout the wall to install the protection.

So there will be an electricians bill to replace the cables plus the bill for a decorator to fix the wall afterwards, possibly plus a plasterer too depending on how bad the damage is.
You may be able to reduce the cost by offering to do the making good yourself if your DIY skills are good in that area.
 
  • Thread Starter Thread Starter
  • #17
Thank you all for your replies.

Davesparks, that sounds pretty much what I expected. I guess wirepuller's suggestion re: trunking would be OK and cheaper but the landlord might not like it.

At least I have always found plastering is pretty easy as long as the area is narrower than a steel float, so hopefully the sparky will be tidy.

Will an electrician be able to do all the electrical work, or will they need to get the supply company in to connect to the meter?
 
The supply company will need to replace the seals on the meter.

As it is a rented flat was he even allowed to drill holes in the wall anywhere? I guess the landlord is not going to be happy.
 
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  • #19
As it is a rented flat was he even allowed to drill holes in the wall anywhere? I guess the landlord is not going to be happy.
The flat had been redecorated prior to occupation and was devoid of fittings like curtain tracks. The landlord had said it was OK to put up such things and until now there had been no problems.

I have always thought that an experienced person is just someone who has already made their mistakes. On that basis I expect that after this whopper, my son is unlikely to ever drill through a cable again. I'm just glad that this educational event only resulted in damage to the building.
 

davesparks

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Will an electrician be able to do all the electrical work, or will they need to get the supply company in to connect to the meter?
That is a bit of a sore point within the industry. Technically the meter operator should make the final connection to the meter, however most electricians will do it on an "it was already like that when I got here, I didn't touch a thing" basis
 
That is a bit of a sore point within the industry. Technically the meter operator should make the final connection to the meter, however most electricians will do it on an "it was already like that when I got here, I didn't touch a thing" basis
Been this way ever since I first got into the industry 20 years ago.
A bit like fight club the first rule about being an electrician is don’t talk about connecting tails to a meter. Nobody does it but everybody does it...
 
Been this way ever since I first got into the industry 20 years ago.
A bit like fight club the first rule about being an electrician is don’t talk about connecting tails to a meter. Nobody does it but everybody does it...
Does what? Lol.
You're breaking the first rule, guys!
 
That is a bit of a sore point within the industry. Technically the meter operator should make the final connection to the meter, however most electricians will do it on an "it was already like that when I got here, I didn't touch a thing" basis
I think in this situation I would have no problems pulling the main fuse, you have exposed live cables after all, I would then ring the DNO to reseal after the repair quoting EAWR as justification for pulling their fuse.
 

davesparks

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I think in this situation I would have no problems pulling the main fuse, you have exposed live cables after all, I would then ring the DNO to reseal after the repair quoting EAWR as justification for pulling their fuse.
I'd be more concerned about pulling their fuse in this situation than in an undamaged installation. The chances are slim but if current was to be flowing through the damage when you pull the fuse there could be some nasty arcing in your hand.
 

Lister1987

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I think in this situation I would have no problems pulling the main fuse, you have exposed live cables after all, I would then ring the DNO to reseal after the repair quoting EAWR as justification for pulling their fuse.
I really do wonder why an isolator isn't part of the service head by design/Bs standard/whatever but we know it's because they want more money in thier bonuses (and charging to install isolators) rather than providing a means to kill power safely, without jeopardising the network (assuming yanking the DNO fuse does any damage....)
 

davesparks

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I really do wonder why an isolator isn't part of the service head by design/Bs standard/whatever but we know it's because they want more money in thier bonuses (and charging to install isolators) rather than providing a means to kill power safely, without jeopardising the network (assuming yanking the DNO fuse does any damage....)
Actually it is more likely to be a lagacy thing than any desire to make money, I'm sure if the whole cutout and meter arrangement was to be designed from scratch today it would be quite different. But it has evolved from the old ISCO and similar cast iron equipment.

It is not the damage done to the network which is the issue with 'yanking' the DNO fuse, it is the serious risk of injury to the person doing it or the long term fire risk if they don't carry it out properly.
If the load is not isolated when the fuse is pulled there will be arcing of the contacts which will leave them permanently damaged potentially creating a high resistance connection which could lead to fire further down the line.
Unseen damage to the fuse carrier or cutout could lead to it falling apart when pulled and leaving live parts exposed or causing a fault at the full fault current of the service, this could cause some nasty burns and blindness for the person doing it.
 
It is not the damage done to the network which is the issue with 'yanking' the DNO fuse, it is the serious risk of injury to the person doing it or the long term fire risk if they don't carry it out properly.
Which is why you should always use appropriate PPE for this type of thing, e.g. insulated gloves, face shield etc. And making sure as far as possible that the supply is off load when pulling the fuse.
 

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