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James2019

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I've moved house and have had a full re-wire and new kitchen fitted in Nov 2020, incl a new electric oven and gas hob. The oven is a Bosch HBG675BS1B. We only actually moved into the properly on 21st Dec. On 23rd Dec (not good timing!) the oven stopped functioning and would not power on. The electricity didn't trip off and the cooker switch neon still illuminated (electric ignition of gas hob above still worked).

Miraculously I managed to get a Bosch contractor to come out on Christmas Eve to take a look. He and I were very surprised to find that the oven and hob were actually connected to a double socket behind the appliance, so the 45A DP cooker switch must just be controlling the power to the double socket. I thought that the cooker was wired directly to the cooker switch, but I was wrong. The Bosch contractor said that this is dodgy, and showed me that this is a 3.6Kw oven and so I understand that a 16A current is required. Therefore it would be impossible for a 13A plug/socket to be OK.

The Bosch contractor plugged in some diagnostic tool which was in the shape of a plug to the double socket, I'm afraid I do not know much about what it showed but he said it was showing a lot of red instead of green, and if he shook it about it would go green. The Bosch guy thought that perhaps the wiring in the socket had overheated and the wiring was not sound inside the double socket anymore. When he plugged the oven back in (to the same possibly dodgy socket) for testing it started working again. He has given me a piece of paper to say that he's looked and that its not fitted in accordance with regulations, dangerous and I should not use it until an Electrician has rectified the issue.

As further info, the oven is not on a completely dedicated circuit, instead it is on a dedicated circuit shared by all kitchen sockets. On the EIC it says that the rating is 20A for this kitchen circuit, which to a clueless person like me sounds like its too low for fridge, oven, dishwasher, toaster, kettle. However in reality this is a discrepancy as when I checked the CU I understand that there is really a 32A breaker for this circuit (BG CUCRB32).

The kitchen fitting was done by a builder at the same time as the re-wire, the full re-wire was conducted by a combination of builder and electrician. I was given an EIC for the work with no observations/abnormalities.

I'm going to get in touch with the Builder who arranged all the work, so he can get the electrician in to sort it out (not him). I would like to give them the opportunity to rectify this work. However I just need some advice:
  • During a full re-wire / new installation should the oven have been put on a dedicated circuit? Or is this just a recommendation and it is acceptable to be on a shared circuit with all kitchen sockets (single electric oven is the only large appliance with high consumption).
  • Should the oven have been wired directly to the DP cooker switch? Instead of 13A socket.
  • Is it acceptable for the electric ignition of the gas hob to share the cooker switch?
  • The NICEIC contractor has signed that reasonable care was taken to design, construct and test the work. Surely this is a lie if it has been wired as above and in the test results table it says 20A rating for kitchen sockets instead of 32A.
  • The builder arranged the electric subbie, having seen this should I have some concerns that corners have been cut with the design, construction and testing? I would like to think that no-one would sign something off which wasn't right, as they have nothing to gain from that, but now this issue has put doubts in my mind.
 
TL;DR
Full re-wire conducted, 3.6kw oven connected to 13A socket and signed off as OK, now I need advice on how to follow up.

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Was it you that ordered the rewire in the first place? This would have brought up the need for a cooker circuit at the time.

How difficult is it for a new dedicated circuit to be run in?

There’s no problem running the ignitor from the same supply as the oven, single socket next to the oven outlet.
 
if the oven came with a fitted plug, it was meant to be connected to the socket circuit. bear in mind the 3.6kW rating is for all elements addes together. in real life it would never pull 16A for any length of time . it is probable that the double socket, being loaded close to it's rated 20A, has failed , cheap socket perhaps? thereis more than 1 way to sort this out at reasonable cost. if you post your location, one of us may be close.
 
Was it you that ordered the rewire in the first place? This would have brought up the need for a cooker circuit at the time.

How difficult is it for a new dedicated circuit to be run in?

There’s no problem running the ignitor from the same supply as the oven, single socket next to the oven outlet.
Yes I ordered the full rewire in the first place, as it was a 1930s semi with old wiring / fuse wire.

We took the house into renovation condition with complete rewire and replastering throughout as I wanted to bring back up to scratch somewhat.

The CU is on the ground floor down the hall from the kitchen. We have solid floors so wiring would be over the ceiling, but we’ve just finished the renovation and all redecorating now.
 
if the oven came with a fitted plug, it was meant to be connected to the socket circuit. bear in mind the 3.6kW rating is for all elements addes together. in real life it would never pull 16A for any length of time . it is probable that the double socket, being loaded close to it's rated 20A, has failed , cheap socket perhaps? thereis more than 1 way to sort this out at reasonable cost. if you post your location, one of us may be close.
The oven didn’t come with a fitted plug, in the product specifications it says plug type: no plug. I never saw it as the kitchen was brand new ordered through Howdens / the builder.

Perhaps it is a cheap double socket which has failed due to the relatively high load. As you suggest as I’m pretty sure the cheapest have been used, as I did not supply these. However it would not have gotten close to 20A I don’t think, as the fuse has not gone on the oven’s plug being used.

Im near Croydon thanks for the suggestion, however I’m just trying to work out what’s right and wrong, before contacting the original electrician to come and fix it, if it is a reasonable request for me to make to them. Otherwise I’ll pay someone else to resolve.
 
if it's a question of just replacing the double socket. ÂŁ60 inc. labour up here. maybe a bit more down in bandit land.
 
What do the manufacturer's instructions say about the supply requirement? That should be the first point of reference. If no plug was supplied it is likely they stipulate 16A minimum, in which case 13A socket is incorrect although might work for a while. If the load is actually <13A then a plug is acceptable although not best practice, as sustained high load on a plug that is never unplugged and replugged can lead to tarnished contact surfaces and heating due to increased resistance.

Sharing a circuit with other appliances is OK, the circuit does not need to be dedicated to just the oven (although it is conventional to have a dedicated cooker circuit to allow for higher load appliances if fitted). However, the point is that it should be on a circuit on which sufficient capacity has been reserved for those appliances, rather than taking a chunk out of the available capacity on your general-purpose socket-outlet circuit which should be available for portable appliances etc.
 
The make and model of the oven is in the OP. If you google the specs, it does say its 3.65kW, 16A, so it is not designed to be simply plugged into a socket.

The builder or electrician should have known the size of the oven if they were supplying it, and designed the installation to suit.

I would get onto the builder first if they were the main contractor. Its his responsibility to do it right first time... if hes got to strip out half the kitchen, and put right afterwards, that will be at his cost.

Good luck
 
The make and model of the oven is in the OP

Oops, sorry I missed that. Then the installation is clearly wrong in a couple of ways.
 
What was the specification agreed for the rewire and in particular for the kitchen? It may be the case that the oven you have purchased is over rated for the wiring that you have specified.
 
Sounds like a cooker circuit has been run in hence the 45a isolator but someone forgot to add a point for the hob and decided to just put a double socket in as a quick solution...

Edit just looked at the pics and no cooker circuit??...strange set up indeed,I’d be calling the spark back to clarify I think mate..
 
Sounds like a cooker circuit has been run in hence the 45a isolator but someone forgot to add a point for the hob and decided to just put a double socket in as a quick solution...

Edit just looked at the pics and no cooker circuit??...strange set up indeed,I’d be calling the spark back to clarify I think mate..

No cooker circuit RCBO in the picture. I think someone realised they hadn't got space in the consumer unit that they've fitted, and so they connected the cooker to the socket ring.
 
The make and model of the oven is in the OP. If you google the specs, it does say its 3.65kW, 16A, so it is not designed to be simply plugged into a socket.

The builder or electrician should have known the size of the oven if they were supplying it, and designed the installation to suit.

I would get onto the builder first if they were the main contractor. Its his responsibility to do it right first time... if hes got to strip out half the kitchen, and put right afterwards, that will be at his cost.

Good luck
Thanks a lot, will give him a try!
 
What was the specification agreed for the rewire and in particular for the kitchen? It may be the case that the oven you have purchased is over rated for the wiring that you have specified.
I'm afraid there was no clearly agreed specification, I only went through the requirements and approx points with him at the start. I decided to use one main contractor to oversee everything to try to avoid issues. This same contractor was used for some small building works, replastering, supply of kitchen (and appliances), fitting of kitchen, replacement boiler, full re-wire.

So the requirements should have been known if paying close attention to detail. I had expected as I was conducting a full re-wire, it would automatically be designed and built to the average requirements of a 3bd home and up to date to the latest safety regulations etc. As I only have very limited knowledge myself!
 
No cooker circuit RCBO in the picture. I think someone realised they hadn't got space in the consumer unit that they've fitted, and so they connected the cooker to the socket ring.
Something odd has gone on. They've put in:
  • circuit for downstaris sockets
  • circuit for upstatairs sockets
  • circuit for kitchen sockets only (inc oven)
I'm personally "OK" with that as long as it is not unsafe. It is just now what I was expecting as I had thought the oven would be put on its own circuit, in hindsight I should have paid closer attention to this but there was a lot going on.

There are two spare places in the consumer unit which are not being used, however the transformer for the Ring doorbell has been put in the spare space of the unused breakers. The doorbell itself is on the outside lights circuit.
 
Would be interesting to see how the kitchen socket circuit has actually been wired, is it a ring final circuit or a radial and what size cable has been used between the cooker isolator and the sockets?
 
Would be interesting to see how the kitchen socket circuit has actually been wired, is it a ring final circuit or a radial and what size cable has been used between the cooker isolator and the sockets?
Hi there, not sure how it has been wired. Apparently it is a ring final circuit going by the installation report, not sure if that is a good thing or a bad thing. See attached from the report. In the report it says it is 20A rating.... but there is actually a 32A breaker in the CU. I need to clarify whether that is a typo, some funny business or what. I will ask them to come and clarify what gauge of wire has been used etc, when I try to get them to come back and fix this oven wiring.
 

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