2 13 amp ovens, does this setup seem right?

[kelchashock]

Hi

I have search the forum and have found information regarding 13 amp ovens but not 2. I wanted to clarify something to make sure that my electrician is correct.

We had an existing 6mm cable which connected to 1 electric oven. This oven has been pulled out and we have replaced it with 2 ovens rated at 2300W or <13 amp.
The circuit is alone and only 4m from the CU so i know it has enough juice to power both ovens. The electrician has used the existing isolation switch and attached a 2 plug socket to it. He intends to attach 2 plug heads to the ovens and then just plug them straight in. The oven guide says they have to be hard wired in although 13amp plug seems right to me as the max is under 13amps.

Question I have is with a fuse at the isolation point and a mcb covering it at the CU, what are the chances that the fuse on the socket will blow? The sockets are plugged behind the ovens, I dont want to find myself in a situation where i am finding myself constantly ripping out my oven to get to the sockets if theres a failure somewhere. Does the fuse on the isolation unit blow first?

Thanks in advance.

 

[securespark]

Plugs and sockets should be made easily accessible.

As for discrimination (which protective device disconnects first), my experience with 13A fuses and 32A B type MCB's is that the MCB will trip before the 13A fuse.

What device is protecting the 6mm² cable?

A single socket should be used for each appliance.

Otherwise the double socket could be overloaded.

My advice is to connect each cooker to a length of suitable 1.5mm² flex connected back to the 6mm² cable via a cooker cable outlet plate.

This does away with the sockets (and 13A fuses) altogether.

Lastly, ensure the device protecting the circuit is rated at 20A and that you have a local DP isolation switch, ideally within easy reach.

 

[AndyPRK]

great price

http://www.ebay.co.uk/itm/45-AMP-DU...al_Electrical_Fittings_MJ&hash=item461ad49fea

 

[EFLImpudence]

I would have just connected both ovens to the cooker connector or fitred one if it was not there.
(difficult to tell from the question.)

Both ovens together are only a maximum of 19.2A so the socket will be fine.

what are the chances that the fuse on the socket will blow?

Nil, unless something happens which will require the oven to be taken out anyway.

The sockets are plugged behind the ovens, I dont want to find myself in a situation where i am finding myself constantly ripping out my oven to get to the sockets if theres a failure somewhere. Does the fuse on the isolation unit blow first?

How many times did the cooker fuse blow?


Edit - now edited as I meant. sorry

 

[kelchashock]

Thanks all for the advice.

Have not had the oven blow up on me yet as its brand new and still not installed. I just wanted to get some advice before I get the kitchen units put in as i wasnt too sure, the ovens says hard wired but it seems the setup I have means i am plugin them in with 13amp.

Just to clarify. The current system that has been installed is:

6mm from CU to isolation switch with fuse ( not sure on the size of the fuse but it was used for our previous oven) Cable from isolation switch to double socket. Double socket is to be used to attach the 2 ovens each at 13amp

 

[EFLImpudence]

6mm from CU to isolation switch with fuse ( not sure on the size of the fuse but it was used for our previous oven)

If you mean the normal cooker switch there will be no fuse in it.

Cable from isolation switch to double socket. Double socket is to be used to attach the 2 ovens each at 13amp

Two 13A fuses, yes, but each oven is only 9.5A when/if both elements are going.

It will be fine.

At least you weren't told that two new 10mm² cables would need to be installed.

 

[securespark]

EFLI:

I'm not in the least offended, but am wondering why you disagree when I also suggested connecting the ovens to an outlet plate.

WRT the socket solution, call me old-fashioned (I asked for that, didn't I? ) but I would rather not load up an accessory rated at 13A beyond that point.

 

[JohnW2]

WRT the socket solution, call me old-fashioned (I asked for that, didn't I? ) but I would rather not load up an accessory rated at 13A beyond that point.

I don't think (m)any people would disagree with that statement, per se, but (as discussed many times, including recently) it's relevance to the current discussion depends upon a $64,000 question to which none of us (even MK's Technical Support folk) really seem to know the answer

The one thing we do know for certain is that BS1363 requires that double sockets pass a temperature rise test at 20A total load.

Kind Regards, John

 

[EFLImpudence]

I'm not in the least offended, but am wondering why you disagree when I also suggested connecting the ovens to an outlet plate.

Yes, sorry. I did edit my reply on rereading removing that bit but it doesn't seem to have worked.
Indeed there is nothing to disagree with in either post.

WRT the socket solution, call me old-fashioned (I asked for that, didn't I? ) but I would rather not load up an accessory rated at 13A beyond that point.

Well, we're back to discussing the rating of double sockets again.

As both oven are a maximum of 19A with no diversity allowance, I think what the installer has done is acceptable.

 

[securespark]

EFLI: No apology needed!

John: We all know cables, switches etc.. have leeway built in to them.

For example, I know that a 32A DP switch will run at 40A all day long.

They may be tested to run at 20A, but the rating of a double socket, as moulded on the back, is 13A.

We don't overload cables when we spec them in an installation. Why should we do the same with accessories?

 

[JohnW2]

John: We all know cables, switches etc.. have leeway built in to them. ... They may be tested to run at 20A, but the rating of a double socket, as moulded on the back, is 13A. ... We don't overload cables when we spec them in an installation. Why should we do the same with accessories?

I think you are underestimating the uncertainties. I'm not talking about 'leeway', nor about overloading anything beyond its rating, but I do believe that (despite what is moulded on the back) there is definite uncertainty as to what the rating of double sockets actually is. For example, as we've often discussed, the technical data sheet for MK sockets (single, double and triple on one sheet) says:

Current rating: 13A per socket outlet (except 3 gang which is 13 amp in total)

If that was meant to mean that double sockets are rated at 13A total, why on earth would they put the bit in brackets just for triple ones (which, as we know, have a 13A fuse)? - they could simply have said that the rating for all their sockets, whether single, double or triple, was 13A total.

If double sockets were not considered safe beyond 13A total, I really doubt that they would ever have been 'allowed' - since it would simply be 'asking for trouble', given that the general public are those who plug things in!

Kind Regards, John

 

[AndyPRK]

Be nice to see some pictures

I think the solution is obvious.
If the ovens come with plugs fitted then use them and fit 2 single sockets.

If they don't have plugs then connect to the connection plate

 

[JohnW2]

I think the solution is obvious. ... If the ovens come with plugs fitted then use them and fit 2 single sockets. ... If they don't have plugs then connect to the connection plate

I think we know the answers to your "ifs" ...

The electrician ... intends to attach 2 plug heads to the ovens and then just plug them straight in. The oven guide says they have to be hard wired in ...

Kind Regards, John

 

[EFLImpudence]

Yes that is true but the reason is to stop the appliance being plugged into a socket circuit.

Although in this case with a 9.5A maximum demand there would normally be a plug on the flex.


However, the above does not mean it is unsafe to use a plug on a 'normal' cooker circuit.
There are many instances of such a circuit being used for a hob and oven where the oven flex requires fusing down.


We do not know in this case if the oven can indeed use all of its elements and 9.5A at the same time so I think it would be unfair to assume that the installer did not know what he was doing.

Presumably had there only been one oven there would be no doubt that plugging it in would be acceptable even if the OP had raised the same query.

So, if you agree, one oven would be alright therefore the only possible objection can be the use of a double socket.

 

[JohnW2]

There are many instances of such a circuit being used for a hob and oven where the oven flex requires fusing down.

I thought ovens could not create overloads

Kind Regards, John