2 13 amp ovens, does this setup seem right?

[EFLImpudence]

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

 

[JohnW2]

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

No need to embolden things - I read it correctly the first time

I thought you folks have been trying to convince me (almost successfully) that if the oven cannot create an overload, then it's flex does not require overload protection (provided that it has adequate fault protection) ... or am I still misunderstanding you?

Kind Regards, John

 

[EFLImpudence]

Ah, but now you have added the part about fault protection.

You know I never advise not down-fusing on the forum, to which I was referring, as the people will not be able to test it correctly (at all).


I did say in my first reply (in this thread) that I would have just connected both to the outlet.

Do we now presume that the installer did not know what he was doing?

 

[JohnW2]

Ah, but now you have added the part about fault protection. ... You know I never advise not down-fusing on the forum, to which I was referring, as the people will not be able to test it correctly (at all).

Fair enough, but ....

I did say in my first reply (in this thread) that I would have just connected both to the outlet.

You did - but were you not saying (advising?) that the oven flexes should be connected to the outlet without any fusing down, even though the 4mm² circuit may well have been protected by a 32A MCB?

Do we now presume that the installer did not know what he was doing?

Not at all. Indeed, if one is concerned about overload protection of the flexes, then his approach would (if it were a 32A circuit, and in the absence of tests of fault protection) theoretically be 'safer' than yours.

Kind Regards, John

 

[EFLImpudence]

You did - but were you not saying (advising?) that the oven flexes should be connected to the outlet without any fusing down, even though the 4mm² circuit may well have been protected by a 32A MCB?

No. DIY advice was not being sought in this thread.
I said that's what I would do.

Do we now presume that the installer did not know what he was doing?

Not at all. Indeed, if one is concerned about overload protection of the flexes, then his approach would (if it were a 32A circuit, and in the absence of tests of fault protection) theoretically be 'safer' than yours.

But this was an electrician.
Perhaps he did test and it was not up to fault protection.

 

[securespark]

All I can say is MK don't write the BS for 1363 accessories.

Lord knows why they wrote that - even they will not endorse the use of two 13A appliances in one of their double sockets...

 

[JohnW2]

You did - but were you not saying (advising?) that the oven flexes should be connected to the outlet without any fusing down, even though the 4mm² circuit may well have been protected by a 32A MCB?

No. DIY advice was not being sought in this thread. I said that's what I would do.

OK. Fair enough.

Not at all. Indeed, if one is concerned about overload protection of the flexes, then his approach would (if it were a 32A circuit, and in the absence of tests of fault protection) theoretically be 'safer' than yours.

But this was an electrician. Perhaps he did test and it was not up to fault protection.

Perhaps, but I rather doubt it. We've been told that the circuit consists primarily of just 4m of 6mm² cable, so I'd be quite surprised if there were not adequate fault protection for the flex.

Kind Regards, John

 

[JohnW2]

All I can say is MK don't write the BS for 1363 accessories. Lord knows why they wrote that - even they will not endorse the use of two 13A appliances in one of their double sockets...

Indeed not - but nor, I suspect, would they say that they were limited to a total load of 13A across both 'outlets'.

If you recall, when I spoke at length to an MK Technical Support guy about this, he said that he could not make much sense of the 'technical data sheet', either - his (rather amazing) 'explanation' being that such documents were usually written by the marketing department! He offered me his personal opinion ('off the record') that the maximum acceptable total load was neither 13A nor 26A but, rather, 'around 20A' - which I think it what most of us essentially believe.

Kind Regards, John

 

[securespark]

Isn't there a 3m rule regarding fusing down?

Further, manufacturers now fit 13A fuses into plugs connected to 0.75 flex, which is considered safe according to the ESC, but not 7671....

 

[JohnW2]

Isn't there a 3m rule regarding fusing down?

That's for when there is 'fusing down', but it's downstream (by a maximum of 3m) of the change in CSA. We're talking about no fusing down, when the load is deemed unlikely to cause an overload and the reduced CSA cable has adequate fault (although not overload) protection.

Further, manufacturers now fit 13A fuses into plugs connected to 0.75 flex, which is considered safe according to the ESC, but not 7671....

That certainly makes little sense, at least as a generalisation. Even 1mm² is not OK with a 13A fuse according to BS7671. However, as above, if the load in question were deemed unlikely to result in an overload and IF fault protection of the cable were adequate, then BS7671 would be happy with 0.75mm².

Kind Regards, John

 

[securespark]

Sorry, I got confused about the fusing down....

Je vais prendre mon manteaux...

 

[JohnW2]

Je vais prendre mon manteaux...

... it's Friday evening and the pubs should be open by now (it's too wet around here, so I'm just going to open my bottle at home!)

Kind Regards, John

 

[kelchashock]

Wow guess there are many ways to do this and its a personal preference ( as long as its safe)

Maybe posting images wont be a bad idea, i'll try get some next time im down at the house.

Ok say i use a cooker outlet instead of the dual socket, I assume i would require the dual cooker outlet as seen in post 2. I assume you cant connect 2 ovens to one connection unit...or can you?

 

[kelchashock]

Hmm ok went back to the house loaded with more knowledge from here. Turns out what I thought was a isolation switch is intact a fcu with a 13 amp fuse and switch. What he has done is taken the cable from the fcu that went to the old oven and attached a dual socket to it.

The diagrams show the intended setup for my appliance setup as it currently stands.

Untitled

• kelchashock
• 10 May 2014
• 1

[/img]

 

[JohnW2]

Turns out what I thought was a isolation switch is intact a fcu with a 13 amp fuse and switch. What he has done is taken the cable from the fcu that went to the old oven and attached a dual socket to it.

Ah, that's a bit different from what we thought, and it casts some doubt on whether the electrician was being sensible. You now have 2 ovens, with a total potential load of about 19.2A running off the one 13A fuse in the FCU (the 'fuse and switch' you mention). Theoretically, that is just about OK, since if one applies 'diversity', one is allowed to consider a total cooking appliance load of 19.2A as representing only 12.76A (i.e. fractionally below 13A). However, particularly given that there will be a 13A fuse in the plug for each oven, that additional ('common') 13A fuse it totally unnecessary, and could possible result in problems (occasionally 'blowing'). If you're sticking with the plugs/sockets, the sensible thing would probably be to change that FCU to an (unfused) (probably 40A) switch or, if a switch is not required (i.e. if both socket switches were accessible), just an appropriate junction box.

Kind Regards, John