Workshop Electrical Feed Issues

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Jelly

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So last night the fuse blew on my workshop, taking the dining room lights with it, long story short, after much messing about up a ladder tracing the cables I discovered the issue...

At some point prior to my ownership (likely during the current kitchen being fitted) the original 10mm² SWA installation was cut off at the wall of the house, and mated crudely with some electrical flex, which then plugs into a 13A RCD socket inside some boxing in, which is shared with the dining room lights, and alarmingly attached to a 60A Fuse (not MCB) in the consumer unit with 1.5mm² Twin and Earth.

Now the fact I had a 60A feed and consumer unit, which had been properly installed (and had building control certs) was a genuine selling point... Whereas what I've found seems like an unnecessary and frankly dangerous cludge.


My planned resolution is to:
  • Replace the 13A socket with an junction box feeding the dining room lights only and use the existing cable run to join this onto the existing downstairs lighting circuit (which has capacity to take the load)
  • Then add an IP68 junction box where the existing SWA was truncated, so I can run new SWA clipped direct to the outside wall and into my meter cupboard connecting to a suitable isolator (I have several metal 63A isolators spare). It has been pointed out to me that for wiring protection a 60A fused switch or MCB would be necessary, this was my original thinking, but whilst posting I got isolator in my head as it's what I'm used to attaching glands for SWA to.
  • Connect that isolator MCB directly into the tails as they leave the 100A RCD that protects the Consumer Unit for the house.
  • Pull the now unused 60A fuse in the consumer unit and leave it disconnected.
Is there any reason I shouldn't do that, or that I should get a sparky in to do this rather than just getting on with it?

(I'll say right now that whilst I know I'm capable of doing all the work to a good standard, I am not formally a "competent person" in a domestic setting; though as far as I can interpret this would not be adding new circuits or otherwise doing Part-P/notifiable works.)
 
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Jelly

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How to you plan to test the work once done?
Was planning to borrow a Megger for the weekend to test for insulation and earthing faults, both in the newly installed section and the circuits on the consumer unit in the workshop.
 

Terrytpot

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Is there any reason I shouldn't do that, or that I should get a sparky in to do this rather than just getting on with it?

(..I am not formally a "competent person" ...)
call me a wuss but now that my house is paid for, should anything untoward happen, I rather like the confidence gained from being able to wave certificates (like the ones I have stating that all my wiring work has been carried out to Part P specifications, has been tested and is not yet due for re-testing) in the face of any loss adjuster who would like to quibble over whose fault it was should my house burn down. That strikes me as something ,which your statement above , kinda opens the door for. Ok, the work isn't particularly complicated but even pro's "screw the pooch" on an alarmingly frequent basis and there's nothing to say you wouldn't either. With that in mind and the fact that most of us only have one family and it lives in that property with you...why try and cut the cost on this type of thing where the saving isn't that huge in relation to the risk you expose yourself to.
 

eribaMotters

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Good points, but other solutions exist. You can do some of the work yourself and get other elements done and the full set-up tested by an approved electrician.
When we moved into our 70's bungalow tail end of 2017 I had the original fuse board replaced with 2 consumer units in parallel. One feeds the house and the other is for workshop and outside lighting. I got the electrician to run a first socket on three circuits which were to become 3 rings. Separate feeds for lighting circuits were also ran from the consumer unit. I completed/extended all of these and then got him back to sign everything off.
I did a similar thing over 20 years ago before the regulations required this. I ran a 10mm cooker cable from the house inside plastic pipe to the workshop 120 feet away. I wired up lighting and power circuits then called in an electrician to fit the required workshop consumer unit and wire it up at the other end.
Going this route you have full control, labour costs are low, you have piece of mind and a certificate.

Colin
 

mikej460

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Mine is a 40A feed from a 40A mcb in one half of a split consumer unit then twin and earth to an external waterproof junction box then SWA (correctly connected with an external swa gland) out to the shop's own consumer unit with mcbs for each circuit. My advice is get an expert to advise you then do it then get him back to test and certify it.

When we moved into our house the electrics were a nightmare along the same vein as you've experienced. In the utility room there was a separate fuse box - it was solid steel with a breaker arm on the outside that looks pre-war! Inside there were no fuses just nails and silver paper! In other areas of the house there were scorch marks on floorboards where cables ran and above the consumer unit unit the floorboards were charred!!
 

Jelly

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why try and cut the cost on this type of thing where the saving isn't that huge in relation to the risk you expose yourself to.

Because the money simply isn't there right now.

So for the minimum of 3-4 months it would take to save up for it to be done properly, the choice is to either:
  • Lose the use of my workshop and lighting to my kitchen and dining room,
  • Persist in using an electrical installation I now know to be a fire hazard,
  • Make it good myself to tide me over until I can afford to have a full EICR, the partial rewire that's almost guaranteed to come with it and regularise the mess I was sold with building control.
Unfortunately I don't have the luxury of being able to just pay for it to get done...

It's not a great situation and I'll be speaking to my solicitors about it as there's a clear deviation from the information provided when I bought, but even if they tell me I could persue it, they're going to want money in order to do so.

Good points, but other solutions exist. You can do some of the work yourself and get other elements done and the full set-up tested by an approved electrician.

...

Going this route you have full control, labour costs are low, you have piece of mind and a certificate.

I know a couple of industrial sparkies quite well who might (in a personal capacity) be willing to assist me in this regard...

So it's probably worth me persuing this option to see if I could make it work.

Whilst I'm not confident I can afford it right now it would be preferable to have external verification and certs if possible.
 

mikej460

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Then I suggest you get the advice from your sparky mates and do it yourself. But you do need to get it certified for peace of mind (y)
 

Old.bodger

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I think you have to accept, however much you wish otherwise, that this is ‘part P’ work. There are areas that you have not specified / may not be aware of.
What is the csa of the swa? How long is the swa? Have you calculated voltage drop? Your connection plan sounds doubtful for compliance, but It is difficult to explain, and your plan MAY be ok. Worst of all, you have advertised the fact that you intend to do it. Thus really helping your insurers if it were to go wrong!
My advise? Get an electrician to do it and sign it off, do without the workshop power until the funds are there. Perhaps live with having to run an extension lead and limit power use for a while. Get a full EICR on the house wiring, it may be your use of words, but the mention of ‘fuses’ makes me fell that it is all rather dated and should be checked. Not being harsh, just I hope realistic!
 

NormanB

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I am not an electrician......but before you take your plans any further....

I would borrow the test equipment and test the SWA cable run now between workshop and where it was cut off to check you have full integrity of all cores, insulation resistance all round and a sound CPC. You should also check what the earthing requirements are and they depend on the workshop building, the type of DNO supply and the distance of the shop from the consumer unit (if that is the only option).

if that is all OK your basic plan is sound. However please note if you are talking about an external meter box then you are not allowed under the terms of the DNO supplier to fit additional equipment in the meter box without their permission, if you ask they will likely say NO. That said they would likely not object to the SWA passing through.

You know your workshop electrical requirements better than I but 60 Amps seems excessive. The workshop should be on its own circuit and protected by both RCD and MCCB this can be achieved with one unit (an RCBO) if you have a spare way in your CU and you can find an RCBO that will physically fit. (I do not know how old your CU is). Best establish what your likely maximum discretionary workshop load is and design the RCBO protection around that.

While in no way casting aspersions on your competence, I did my workshop electrical installation from scratch two years ago and had a chat with an electrician showed him my design intent which included provision for 32A protection, 30Metres of SWA (showing him the route) and a ring final circuit, plus lighting. All calculations shown. He agreed it was compliant with regs and doable, inspected at first fix, again at second fix when he tested everything and he made the final connection at the CU, issued part P certificate and charged me £70. It was worth every penny for peace of mind. He only lived round the corner and did all the ‘work‘ on the way home at his convenience - we were both very happy.😀
 
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Jelly

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I think you have to accept, however much you wish otherwise, that this is ‘part P’ work...

Your connection plan sounds doubtful for compliance, but It is difficult to explain, and your plan MAY be ok.

Reading Part P in detail, the nub is that currently the workshop Consumer Unit is actually just a large circuit coming off the house's CU. Whilst that's been horribly compromised, in principle modifying it isn't notifiable.

However my preference is to effectively have two distinct CU's, one for the house and one for the workshop.

In transfering the workshop CU onto the feed coming out of the DNO's equipment, that existing circuit becomes a new installation which is in scope for Part P.

If I'm willing to tolerate continuing to use the old fuse on the House CU, then it's probably not notifiable, but I don't think it's worthwhile when I know that will need to come out in due course.

Worst of all, you have advertised the fact that you intend to do it. Thus really helping your insurers if it were to go wrong!

I'm not inclined to think that way, I'd much rather have the advice and minimise the risk of things going wrong in the first place.

It's now clear to me that getting a sparkie in to certify the work (or tell me it's not up to spec and needs to be rectified) is going to have to get built into the cost, in order to minimise my exposure in terms of insurance.

Get a full EICR on the house wiring, it may be your use of words, but the mention of ‘fuses’ makes me fell that it is all rather dated and should be checked. Not being harsh, just I hope realistic!

No you read that right, it takes BS1361 fuses, although some circuits have been upgraded to plug in MCB's, and there's a separate RCD between the DNO equipment and the CU, which seems like a cludge to technically meet the requirement that came in with BS7671:2001.

I know full well a significant re-wire is going to be required in the house, and plan to get an EICR in the near future to prioritise what gets done first.


You know your workshop electrical requirements better than I but 60 Amps seems excessive.

60A is what the current installation was designed for (before it was mangled), it's probably a bit more than my projected requirements, but dropping it to 40A would run quite close to foreseeable peak loads during the winter, and I'd rather not have the breaker tripping unnecessarily.
 

NetBlindPaul

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I am not sure I understand the exact layout of this, further than the SWA haas been chopped off botch connected to some flex which is plugged into a socket, and you seem to have some 1.5mm sq. wiring conneted to a 60A fuse in your consumer unit?

Firstly, I am not sure that any domestic consumer units wth RCD’s and MCB’s are sutable for haaving a fuse holder with a 60A fuse inside fitted. Most are limited to 32A fuses.
Many are not suitable for a 63A MCB.
 

NetBlindPaul

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ALL domestic electrical work comes under Part P, the difference is whether it is notifiable or not.
Thus all work needs to comply with BS 7671 as required by Part P, which is law.
 

NetBlindPaul

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So last night the fuse blew on my workshop, taking the dining room lights with it, long story short, after much messing about up a ladder tracing the cables I discovered the issue...

At some point prior to my ownership (likely during the current kitchen being fitted) the original 10mm² SWA installation was cut off at the wall of the house, and mated crudely with some electrical flex, which then plugs into a 13A RCD socket inside some boxing in, which is shared with the dining room lights, and alarmingly attached to a 60A Fuse (not MCB) in the consumer unit with 1.5mm² Twin and Earth.

Now the fact I had a 60A feed and consumer unit, which had been properly installed (and had building control certs) was a genuine selling point... Whereas what I've found seems like an unnecessary and frankly dangerous cludge.


My planned resolution is to:
  • Replace the 13A socket with an junction box feeding the dining room lights only and use the existing cable run to join this onto the existing downstairs lighting circuit (which has capacity to take the load)
  • Then add an IP68 junction box where the existing SWA was truncated, so I can run new SWA clipped direct to the outside wall and into my meter cupboard connecting to a suitable isolator (I have several metal 63A isolators spare). It has been pointed out to me that for wiring protection a 60A fused switch or MCB would be necessary, this was my original thinking, but whilst posting I got isolator in my head as it's what I'm used to attaching glands for SWA to.
  • Connect that isolator MCB directly into the tails as they leave the 100A RCD that protects the Consumer Unit for the house.
  • Pull the now unused 60A fuse in the consumer unit and leave it disconnected.
Is there any reason I shouldn't do that, or that I should get a sparky in to do this rather than just getting on with it?

(I'll say right now that whilst I know I'm capable of doing all the work to a good standard, I am not formally a "competent person" in a domestic setting; though as far as I can interpret this would not be adding new circuits or otherwise doing Part-P/notifiable works.)
My advice s that as the wiring has not been protected against overload, and the fuse has blown, then there is a good chance that it has been overloaded, and, may, have suffered damage, therefore it will require verifiction, an IR test may be enough, it may not.
The same goes for the consumer unit, that may have suffered from thermal damage if it is not designed to supply a 60A. load.
Therefore my advice is to get a competent electrician to sort this.

That said, I will look further at what you are proposing and see if I can get my head round it and try to post some advice later, if you insist on doing this work yourself.
Also as you are looking at modifications to the house
 

sometimewoodworker

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Is there any reason I shouldn't do that, or that I should get a sparky in to do this rather than just getting on with it?
It sounds as if you are going to be modifying a connection to the house CU or a circuit that’s in it. If true then you will have to ensure that the CU is compliant, it almost certainly is not so you will need a new consumer unit, I’ve just had a sparky quote of £650 just for the CU that is a VAT free price as he is a small business.
 

bryan267

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Little while since I had my workshop wired. There are comments that a 60amp feed shouldn’t come from a CU, I suspect that is correct. You mention tails. My supply was split after the meter, tails to the existing CU, another to my annex and a further to my worship via two switches at the end of each tail. My brother is a sparky so did it for a an iou. Earth to Worksop was on the steel wire of the swa, don’t see why you couldn’t put a junction in where the existing swa is short. I did all the work from the switch to, and inside, the workshop, no idea what that would have cost but it wasn’t much time. I would certainly use a sparky where working before the CU. Good luck.
 

J-G

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that is a VAT free price as he is a small business.
That is somewhat incorrect. He may be a small business who is not registered for VAT purposes but he will be paying VAT on whatever components he buys in and will be passing that cost on to you. He will not be able to charge VAT on his labour and he will not be able to reclaim the VAT that he has paid for materials.
 

Spectric

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In simple terms you need an electrician, this is already a bodge job and needs rectifying by someone who knows what they are doing and can undertake the relevant test & inspection in order to give you a small works certificate. The workshop needs to be completely independant of your household circuits and I would be very concerned about how safe the installation is and if it is correctly and safetly protected, without knowledge & expensive multifunction testers that can measure prospective fault currents and impedance of the CPC's you are working in the dark.
 

Sandyn

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It sounds like you really need the assistance of people on here to get you out of a real problem. I'm sure most people on here have been REAL tight for money at some stage in life. It would get you something safer than what you have. It sounds like you will have no option and will do it yourself anyway.
The first stage is to establish exactly what you have. A wee pencil sketch would be helpful to everyone. Those who think this is the wrong approach and helping you would expose them to any risk don't need to contribute.
 

pe2dave

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Was planning to borrow a Megger for the weekend to test for insulation and earthing faults, both in the newly installed section and the circuits on the consumer unit in the workshop.
More specifically, what recognised cert of conformance will you hand over to a new buyer?
Do the work, fine, but get a qualified lecky to check it out and print the cert?
Sadly, that will mean a full house check, all lights / outlets etc. But at least you'll know it's good and safe.
 

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