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