Three CUs attached to 100A single phase supply

[Tontoe]

Hi
Had a call out to a customer yesterday who'd had a cooker delivered from John Lewis, but the sparky had refused to connect it as the supply was 32A on a 4mm cable. Manufacturer instructions specify 6mm cable but don't give rating of appliance, and it's not on the data plate, but manufacturer instructions take precedence etc etc.

Well, I thought, ring manufacturer (AEG) and check, but their line was closed due to "temporary difficulties".

Then I looked in the under-stairs cupboard, and despite it being a small 3-bed terrace, I found...

Three consumer units are running off a 100A BS1361 cut out - TNS supply.
1) 8-way Wylex insulated with 7 replacement plug in MCBs and one rewireable - 2x6A, 1x5A rewireable, 1x16A, 3x32A and 1x40A. the original cooker ran off one of the 32A MCBs. Mixing MCB & rewireable not advisable, I think?
2) 6-way Wylex insulated with 6 replacement plug in MCBs - 5x16A and 1x20A
3) 6-way Contactum with a mix of types of MCBs - both C and B types - 1x6A, 2x32A, 2x25A (really) and 1x10A - not arranged in the logical order they should be.
The last one appears to be connected to a PV array (or at least one of the breakers is labelled as such) and has a test & inspection notice dated late 2011, but I can't see a local AC isolator.

Only about a third of the circuits are labelled and the customer couldn't tell me what controls what. She said they had a heat pump but also electric heating, although I didn't see any storage heaters.

I suspect the 6-way Wylex was for storage heaters, and may be redundant. She said the PV installer put in the Contactum, but why put in a 6-way unit for a 9-panel array?

The customer now has a redundant and expensive cooker.

Logic says "walk away", but I'd like to help her if I can as she seems a nice woman. However, I suspect tracing circuits, along with the related EICR to try consolidating the CUs, will be a nightmare best avoided. If I did run a new circuit in 6mm it would need RCD protection, which would mean adding another small CU.

Think I've talked myself out of this one, but I'd welcome any suggestions.

 

[Heisenberg]

Have you had the fronts off the CUs, are all the mcbs cabled up?

 

[Tontoe]

Not yet - only went to verify/inspect the cooker connection arrangement and then found the stuff under the stairs.
Suspect some of the ways may be empty/redundant, but it's all a bit of a mess...
As a responsible spark, I want to help the customer and ensure she's safe, but it just looks like trouble...

 

[Clive P]

Hi,

Could be a nice little earner, work is tight looking at some of the posts on here. Sounds like the 6 Way Wylex was an old Night Store board , now wired as radials. The other Two Boards, well one may be used and the other redundant; you'll need to have a good look to confirm one way or the other. Why not offer to do an EICR and take it from there, your'e happy and hopefully the customer will be happy.

Regards.

 

[TaffyDuck]

Cant see the problem tbh. Its very rare in the extreme that a cooker will be pulling full load and as you already have a 4mm supply use a 20 amp MCB ( up to 28 amp dependent on installation method) and explain the possible limitations to the customer. Cable is protected and the customer will likely have no problems at all.

 

[i=p/u]

Put it on 20A is what I thought, saying its safe but might not hold at christmas,

 

[Andy78]

The job sounds like a bit of a mess but probably easy to make sense of once you start digging. Probably lots of redundant circuits there.
If the manufacturers instructions say a 6mm, then a 6mm it gets. Very unusual for the rating not to be stated in instructions or on the appliance. Sure you have looked everywhere for it ? You could always google the model number to get some info.

 

[Tontoe]

Thanks everyone.

Didn't seem to be any rating mentioned in the instructions, on the plate on the back of the appliance or on the web (had similar issues with Bosch appliances a month or so ago); or maybe I'm just blind/stupid! It was a big, multifunctional induction beast, which was my reason for concern.

Finally got through to AEG and they say it requires a 32A breaker. 4mm T&E is rated at 36A for Clipped Direct reference method, I think? So the existing circuit would be okay... but instructions specify 6mm, and they take precedence.

However it's academic because when I finally got through to AEG, although they agreed "unofficially" that the 4mm cable/32A breaker would do the job, they also said that if it wasn't fitted by an authorised AEG Service Agent, the guarantee would be invalidated.

Have given customer Service Centre details and will wait to hear what she decides on sorting out the mess. She's kindly offered to pay for my time.

Thanks again for all help and advice.

 

[Heisenberg]

However it's academic because when I finally got through to AEG, although they agreed "unofficially" that the 4mm cable/32A breaker would do the job, they also said that if it wasn't fitted by an authorised AEG Service Agent, the guarantee would be invalidated.

I can guess what E54 will say... :furious3: LOL

 

[Deleted member 9648]

Am I missing something here?....she wants her cooker connected,which may involve replacing the 4.0 for 6.0,and you are talking EICR's and tracing all the existing...???...she just wants a cooker doesnt she?

Why get involved with the rest of it?

 

[MDJ]

The important bit was the fact you said the manufacturer stated 6mm2 cable, that ends the argument whether I would agree with it or not, can you imagine what the Judge would say if you installed a cooker and didn't use the cable suggested by the manufacturer, and the manufacturer standing in court giving his companies reasons why LOL, you would lose the case even if you had good reason to use the 4mm2 cable.

 

[Tontoe]

Thanks again everyone.
Yep - manufacturer's instructions always take precedence, so I always cover my a**e and follow them - even the ones that seem nonsensical. Guess they are there for a reason, even if it's a misprint...

 

[snowhead]

So unless the supplier of the cooker, presumably an authorised AEG service centre, stated it must be supplied via 6mm before the sale, they the supplier will have to collect and exchange the cooker for a suitable one, free of charge.

 

[shocking_eg]

ratings on appliances are usually printed on the side of the door when you open it. not on the back of the appliance

 

[Guest55]

a few points to consider......

warranty invalid if not fitted by aeg installer - i'd be considering this a breach of consumer rights to be honest and would challenge it.

manufacturers instructions always take precedence - nope , bs7671 says they should be considered , not followed blindly like a lemming.

you have a 32a / 4mm circuit available for the cooker so use it , no need to start fannying about with the rest of the houses wiring , thats not the job you were instructed to do.