Possible dodgy oven wiring discovered

[Midwest]

Might be my eyes deceiving me, but the wires for circuit 4 (central heating) seem slightly larger gauge, than the wires for the RFC‘s.

Where is the FCU for the CH located OP?

 

[brianmoooore]

Might be my eyes deceiving me, but the wires for circuit 4 (central heating) seem slightly larger gauge, than the wires for the RFC‘s

I thought that as well. Doncaster cable for that circuit only?
Also wondering why the heating needs a 16A MCB all of its own. All the CH systems I've ever wired have been through a 3A fuse, except for a few larger systems where the fuse was 5A.
I also subscribe to the theory that a smoke detector feed should be incorporated into a circuit whose failure would be obvious, such as the downstairs or upstairs lights, although I know there are those on here who disagree.

 

[James2019]

Might be my eyes deceiving me, but the wires for circuit 4 (central heating) seem slightly larger gauge, than the wires for the RFC‘s.

Where is the FCU for the CH located OP?

Hi there, if I I understand the question correctly the boiler is located upstairs in the wiring cupboard on the landing. The fused spur for it is located there.

 

[James2019]

I thought that as well. Doncaster cable for that circuit only?
Also wondering why the heating needs a 16A MCB all of its own. All the CH systems I've ever wired have been through a 3A fuse, except for a few larger systems where the fuse was 5A.
I also subscribe to the theory that a smoke detector feed should be incorporated into a circuit whose failure would be obvious, such as the downstairs or upstairs lights, although I know there are those on here who disagree.

Boiler is a new mid-range combi boiler, separate circuit wasn’t any special request from me! No water tank or immersion heater.

 

[James2019]

Development is they will come tomorrow to discuss and take a look. Builder speaking with the spark in the morning.

He said he was thinking they will just wire the oven to the cooker switch, however I have said you can’t put a 16A appliance on an RFC... thanks to your advice on here! Then he talked about it being straightforward to convert an RFC to a radial. However I said if 2.5mm cable has been used (unconfirmed) then you can’t use a 32A breaker and suggested it will be a problem as 4mm will be needed. Otherwise the cables could overheat and not be protected by the breaker. So he said he will check with the spark in the morning and let me know the plan.

I’ll see what options he’s willing to offer me... at this rate I’m still strongly leaning if you just getting a 13A oven below 3kW to save me any more stress over this.

 

[littlespark]

It was quite common to utilise an old immersion supply to supply a new boiler, and it just stuck that a 16A radial was needed for a new circuit for the same thing.

I wouldn’t bother bringing that issue up as well as the oven. The boiler will (should) have a 3A fuse in the fused spur

One other thing I’d like to bring up would be fire detection. How many smoke detectors were actually fitted as part of the rewire?

 

[brianmoooore]

post removed! Getting confused between threads.

 

[James2019]

It was quite common to utilise an old immersion supply to supply a new boiler, and it just stuck that a 16A radial was needed for a new circuit for the same thing.

I wouldn’t bother bringing that issue up as well as the oven. The boiler will (should) have a 3A fuse in the fused spur

One other thing I’d like to bring up would be fire detection. How many smoke detectors were actually fitted as part of the rewire?

Yes won’t bother mentioning the boiler, otherwise he’ll start to think I’m being funny with him.

Smoke detectors are fitted on upstairs and downstairs landing as part of the rewire, plus a heat detector in the kitchen.

 

[Midwest]

Yes won’t bother mentioning the boiler, otherwise he’ll start to think I’m being funny with him.

Smoke detectors are fitted on upstairs and downstairs landing as part of the rewire, plus a heat detector in the kitchen.

I was just thinking perhaps your electrician had installed a cooker supply, possibly 4mm in your case. Perhaps he used it to supply the CH instead.

Long shot, but does seem a bit strange to use a larger cable for such a radial circuit.

 

[James2019]

I was just thinking perhaps your electrician had installed a cooker supply, possibly 4mm in your case. Perhaps he used it to supply the CH instead.

Long shot, but does seem a bit strange to use a larger cable for such a radial circuit.

There did used to be an immersion heater there, before we replaced the boiler and conducted the rewire. In the test results of the installation report it says 2.5mm wire though, so maybe it is just the photo?

 

[telectrix]

but did he know the difference between 2.5mm cable and wet string?

 

[James2019]

Right the builder has been back today, he said that the electrician has had to self isolate and conduct a COVID test. He said the electrician will come back after approx 5 days if the test says clear. The electrician will come for testing and updating the installation report.

The electrician advised him to update the oven wiring. So now behind the oven, the oven cable goes to a mounted white plate which has no switch. I understand this to be a 20A 1 gang outlet plate? Directly next to it is the 1 gang outlet for the gas hob ignition. I understand that these are wired so the cable goes from the switchless plate, to the 1 gang switch, then to the cooker isolator switch. The hob ignition I understand is on a 5A fuse.

The breaker for the circuit has been changed to 16A. I asked surely if the oven happens to draw near to its max and you boil a kettle at the same time (or run dishwasher), it will be too much current and it will trip the circuit. He said it's not a problem and phoned the electrician to reassure me that it will "definitely" be fine, and talked about how the RFC is two 2.5mm cables so it is like having 5mm. They were speaking in their local dialect together, so could not hear the whole conversation.

Can you confirm to me what has gone on here is not a viable solution, and is a bodge job to get the oven on? If the kitchen circuit was intended to have a 32A capacity, it must be impossible for it to be magically sufficient to have a 16A capacity for dishwasher, kettle, toaster and portable appliances on the same circuit. We ran kettle, fridge, microwave, oven (on fan mode) to see if it tripped, but it worked OK. So that was his demo of "all ok".

I probably should have said don't do anything at all after I heard the plan, which was delivered to me on the spot when he showed up. But I had their assurances and that they can come back if there is any issues, so I agreed with trying their suggestion incase it is my own misunderstanding of how things work.

 

[Baddegg]

If I’m understanding correctly then no it’s still not correct, the oven needs its own circuit as it’s over 2kw....all they have proposed is limiting the whole kitchen to 2 x 16a radials run off of the same protective device?.......which could still mean the cooker is just in the end of a radial circuit with other sockets along its length...I get concerned at your phrase “local dialect”.....what is they local dialect?......I don’t want to concern you here but after looking at that consumer unit and your last post I’d be concerned as to the level of workmanship in your property.....

 

[Strima]

So the builder has removed the 32 amp MCB for the ring final circuit and replaced it with a 16 amp MCB?

Where is the builder from? Is the electrician a relative of the builder?

Can you post a copy of the EIC for us to view? You would need to redact any personal details of yourself and the builder/electrician.

 

[JBW175]

So the electrician stays at home, gets builder mate to alter characteristics of circuit, no testing carried out. Nothing sounds right from what I’m understanding from your post.

 

[littlespark]

So the builder is also an electrician? Must be, or he wouldn’t be working on it.
Sounds like another bodge job.
You’ve told him the oven book says it needs a 16A supply, so in his little logical mind, he’s given it a 16A by changing the mcb.
He could have left it on a 32, oven is fixed load, so can’t go over the rating.

Im sorry to say this is very troubling.

Did you say where in the uk you were earlier in thread? I’m sure one of us could give you a professional opinion in person.

 

[Baddegg]

@James2019.......have you ever actually meet or seen the “electrician”?

 

[James2019]

The builder and electrician are both from Poland, I do not believe they are related. However they could be friends. I did briefly meet the electrician working with him during the re-wire, which I believe was the electrician who checked the design/testing etc. However I was not living in the property at the time as it was being completely gutted.

I'm located near Croydon, SW London.

EIC attached, please let me know if I've accidentally left any personally identifiable information in the attachment. The electrician is supposed to come to re-test and correct the certificate, due to the issue with the kitchen circuit.

 

[brianmoooore]

A possible solution, although still far from ideal, and dependant on where the cooker switch sits in the ring, and a few measurements, would be to split it at the cooker switch, fit two 20A breakers in the CU (smoke can be stuck in with lights to make room) and form two radial circuits.
If the cooker happens to be at one end of the ring (I doubt if load distribution figured in the design of this RFC), or only ends up with a socket or two not likely to be used for kettles, dishwashers or washing machines, then this could be a decor friendly solution.
It will still be non compliant and would attract a C2 from me if I came across it when doing a test report, but it could be safe and reliable.

 

[Pete999]

The builder and electrician are both from Poland, I do not believe they are related. However they could be friends. I did briefly meet the electrician working with him during the re-wire, which I believe was the electrician who checked the design/testing etc. However I was not living in the property at the time as it was being completely gutted.

I'm located near Croydon, SW London.

EIC attached, please let me know if I've accidentally left any personally identifiable information in the attachment. The electrician is supposed to come to re-test and correct the certificate, due to the issue with the kitchen circuit.

Bit far for me Mate keep us posted I hate someone not conversant or qualified making a buck out of something he/She should leave to someone that knows their trade, builders should stick to building, good luck Mate hope you get it sorted

 

[baldelectrician]

Have you checked the details of the electrician / company on the NICEIC website?

You can complain to the NICEIC about the work if the contractor is NIEIC registered.

 

[Midwest]

Have you checked the details of the electrician / company on the NICEIC website?

You can complain to the NICEIC about the work if the contractor is NIEIC registered.

I think the OP has, and the NIC responce was the norm.

 

[FatAlan]

Easiest solution is just to get them to replace the oven with one that runs off a 13amp socket. Other than that, it’s a dispute over whether the rewire spec should have had a dedicated cooker circuit and you’d like to think that there was one there originally.

 

[James2019]

I think the OP has, and the NIC responce was the norm.

I have the details of the electrician and his company name from the report, and they match up with whats on the NIC website. However to follow their resolution process, you must go back to the installer first to raise your concerns and allow them a chance to resolve.

I will definitely send them a complaint when I am completely done with any more visits or trying to squeeze any compensation out for this (such as oven replacement). I do not suppose they will do much, however if there is any chance this will help stop this happening to anyone else then that will be good.

 

[James2019]

Easiest solution is just to get them to replace the oven with one that runs off a 13amp socket. Other than that, it’s a dispute over whether the rewire spec should have had a dedicated cooker circuit and you’d like to think that there was one there originally.

I think you're right there. Wife quite adamant about keeping the oven, however I think it will be preferable to get an oven that runs off a 13A socket rather than run a new circuit since we've finished plastering, redecoration and moved in last week!

In the old wiring for the kitchen circuit I believe 6mm cable was used and a BS3036 30A rated fuse. They had a gas oven/gas hob. The old wiring (pre-rewire) had 22 C2s when I had an EICR conducted (I used someone else for the EICR when buying the house). I think that was mainly due to the age of the install/changing norms.

 

[telectrix]

if that 6mm cable is still in situ, maybe it could be re-used to provide a dedicated cooker circuit.

 

[FatAlan]

Did my kitchen a year or so back. Although I put in a dedicated feed for ovens, both the oven an microwave combi are on standard 13amp plugs. Loads of good options out there .. you just need to sell it to the Mrs ? Appreciate that it’s a compromise and the ‘builder/spark’ has let you down ?

 

[Midwest]

Did my kitchen a year or so back. Although I put in a dedicated feed for ovens, both the oven an microwave combi are on standard 13amp plugs. Loads of good options out there .. you just need to sell it to the Mrs ? Appreciate that it’s a compromise and the ‘builder/spark’ has let you down ?

Thing is 'we' all know and expect an 'oven' to be on its own circuit, just like a shower.

 

[Lucien Nunes]

We recently had a thread, perhaps someone else can find it (I don't have time now to trawl) about connecting a load over 13A to an RFC. Careful study of the regs seemed to indicate that a B16 MCB is permissible in place of a 13A fuse to BS1362. That would allow the existing oven to be connected to a 32A circuit.

If that is the case, notwithstanding the recommendation for all large loads to be supplied independently of a general socket-outlet RFC, I do not think there is much to gain by changing the oven to one with a lower maximum current. The power used during cooking under thermostatic control depends on the heat loss from the oven, not the rating of the elements. There are some subtleties here that I won't go into now but suffice to say the effect of a slightly lower element rating on the usability of the circuit for other loads isn't worth the cost and effort of changing the oven.

 

[Lucien Nunes]

See this post:
16A OCPD acceptable on 32A RFC

I would consider that much more satisfactory than fusing the circuits down. The present situation with an undersized MCB that does not trip in practice, is still non-compliant if the design load exceeds its rating. This leads to the undesirable situation of the MCB having to withstand regular small non-tripping overloads.

 

[brianmoooore]

16A is the maximum load of the oven. I would be surprised if it wasn't designed to be fused at 32A, as it would be if connected to a standard cooker circuit.
What do the manufacturer's instructions say on the subject.

 

[FatAlan]

Going back to the OP. Does still beg the question why the current oven isn’t working correctly bearing in mind no OCPD devices have tripped. I take it that it’s not one of those hardwire connections with a multiphase option that has been wired incorrectly meaning only half the elements work?

 

[Lucien Nunes]

Post #1 did imply that there was an intermittent contact / connection at the socket, as the socket tester used by the man from Bosch at first indicated a fault that disappeared after they plugged things in and out.

 

[Lucien Nunes]

I would be surprised if it wasn't designed to be fused at 32A

Good idea to check. I have definitely seen two ovens of 3.6kW / 16A rating that specified maximum 20A fuse or MCB but that is not to say this one requires it. In any case, as per my post above, it seems in order to fuse down to 16A with a 60898 from an RFC.

 

[James2019]

See this post:
16A OCPD acceptable on 32A RFC

I would consider that much more satisfactory than fusing the circuits down. The present situation with an undersized MCB that does not trip in practice, is still non-compliant if the design load exceeds its rating. This leads to the undesirable situation of the MCB having to withstand regular small non-tripping overloads.

Thanks for taking the time to dig that up and offer the suggestion. This does sound promising.

 

[James2019]

Post #1 did imply that there was an intermittent contact / connection at the socket, as the socket tester used by the man from Bosch at first indicated a fault that disappeared after they plugged things in and out.

That’s right, it worked after shaking it around. Then it went off again. When the guy came today he said the fuse had gone in the plug this time. Now that it is wired directly after the changes today, it is currently working OK temporarily until this is resolved properly.

 

[telectrix]

Yes won’t bother mentioning the boiler, otherwise he’ll start to think I’m being funny with him.

Smoke detectors are fitted on upstairs and downstairs landing as part of the rewire, plus a heat detector in the kitchen.

bloody glad i fitted one..... 2 weeks after, i set chip pan on fire. that heat detector saved me a lot of grief from 'er indioors, as damage was slight, b
not to mention my life and that of the 4 dogs.

 

[brianmoooore]

. that heat detector saved me a lot of grief from 'er indioors, as damage was slight, b

Surprised to hear that! I've always considered heat detectors as "your house is on fire, get the hell out of there" and (correctly installed and in sufficient numbers) smoke detectors as "you are about to set your house on fire, if you don't do something quick"

 

[telectrix]

heat detector triggers at 58 deg, C. mounted within 6 ft. of hob. smoke detectors in kitchens are a no-no. every time you do toast or fry bacon, they go off. i was lucky. the flames off the chip pan were only 2 ft. high. a wet towel sorted. now have a dry powder extinguisher, same as the one in the van, in kitchen . best of it was, the parnoid d-i-l-called ambulance and fire service. all the fire boys did was to take the still hot but out chip pan into the front yard and cool it with a water hose. ambulance service wanted me to go to ozzy (smoke inhalation ). sod that. dogs left home alone and no beer in ozzy. no brainer.

 

[Baddegg]

Smoke inhalation ? how would they know tel! ?