A very basic question on a cooker radial circuit

[KeithT]

I hope that I am not trespassing because I am not an electrician but I am trying to get an answer to what I know must be a very basic question.
I wish to replace an existing built-under single oven which is plugged-in to a radial circuit using 2.5mm T&E on a 16A MCB. The wiring is 15yrs old on a Hagen consumer unit.
The new oven would be a double oven with a max 4KW rating at 18A.
My question is whether or not it could be plugged-in to this circuit, or does it need a new one in 6mm?
I appreciate that the present MCB would be inadequate.
The manufacturers won't advise on H&S grounds, not even to say if they designed it to be plug-in or not (!) and I don't feel I could call-in an electrician just to be advised "Plug it in!"

 

[randyrat]

It all depends on factors which derate the cable, i.e the way it is routed, length of route, ambient temperature etc. You could find that the cable is too light for 18A. Certainly now most cookers are run in 4 or 6 mm as standard.I would take the opportunity to uprate to 4.0mm to be on the safe side. Upgrade your mcb to an rcd or rcbo and you are sorted.If its a shortish run with good access a decent sparky will probably charge you a couple of hundred quid for this....but check his credentials first...or better still, go for a friends recommendation. There are a lot of cowboys out there......"Sorry mate, you'll need a full re-wire, be about 4 grand" (Run a mile)

 

[KeithT]

It all depends on factors which derate the cable, i.e the way it is routed, length of route, ambient temperature etc. You could find that the cable is too light for 18A. Certainly now most cookers are run in 4 or 6 mm as standard.I would take the opportunity to uprate to 4.0mm to be on the safe side. Upgrade your mcb to an rcd or rcbo and you are sorted.If its a shortish run with good access a decent sparky will probably charge you a couple of hundred quid for this....but check his credentials first...or better still, go for a friends recommendation. There are a lot of cowboys out there......"Sorry mate, you'll need a full re-wire, be about 4 grand" (Run a mile)

Randyrat
Many thanks for this.
The cable run is under 8m in the vented underfloor.
However, it is more or less the answer I expected but I felt that I should just be sure and not end up with what might have been an unneccessary amount of upheaval.
I have identified a spot where I can cut an access hatch without needing a carpet refit. Now to find a local electrician.
Thanks again
Keith

 

[mrloy99]

I hope that I am not trespassing because I am not an electrician but I am trying to get an answer to what I know must be a very basic question.
I wish to replace an existing built-under single oven which is plugged-in to a radial circuit using 2.5mm T&E on a 16A MCB. The wiring is 15yrs old on a Hagen consumer unit.
The new oven would be a double oven with a max 4KW rating at 18A.
My question is whether or not it could be plugged-in to this circuit, or does it need a new one in 6mm?
I appreciate that the present MCB would be inadequate.
The manufacturers won't advise on H&S grounds, not even to say if they designed it to be plug-in or not (!) and I don't feel I could call-in an electrician just to be advised "Plug it in!"

2.5mm cable can carry 26amps,however,if imbedded in thermal insulation,eg,in wall or ceiling,this can be reduced to just 13amp.If you change your 16amp mcb to a 20amp mcb(or rcbo if reqd)I don't think you will need to change cable.Also a 13amp plug will no longer be suitable and the appliance will either need to be "hard wired" in to the circuit or else fit a suitably rated plug and socket.

 

[Spudnik]

If the cable is under a suspended floor then its fine.

Even with diversity a 16A MCB should be ok, but i would uprate to 20A with a 20A DP switch in place of the socket outlet.

 

[isitintheregs]

I may be missing the point here but if the appliance is supplied with a manufacturer fitted 13a plug (ie moulded to the flex) you will probably void all warranties if you do anything other than plug it in to a 13a socket. In which case your exsiting wiring is fine as is because the plug fuse will blow before the limit of the 2.5mm t&e or 16a mcb is reached. Tread carefully before you cut of the plug!

 

[Spudnik]

True, does depend on if it has been supplied with a 13A plug top fitted.

 

[Alan.P]

I may be missing the point here but if the appliance is supplied with a manufacturer fitted 13a plug (ie moulded to the flex) you will probably void all warranties if you do anything other than plug it in to a 13a socket. In which case your exsiting wiring is fine as is because the plug fuse will blow before the limit of the 2.5mm t&e or 16a mcb is reached. Tread carefully before you cut of the plug!

The OP didn't mention whether the new appliance had a plug top fitted or not, I would have guessed not seeing as how it's rated at 4kW, just my tuppence worth

 

[KeithT]

The OP didn't mention whether the new appliance had a plug top fitted or not, I would have guessed not seeing as how it's rated at 4kW, just my tuppence worth

No there wasn't a plug fitted but neither was there one on the electrical circuit for the Bosch gas hob which is rated at 3A! Pennypinching? (I was under the impression that nowadays all appropriate appliances should be fitted wih a plug.)
Problem solved though.
An electrician sourced via a friend installed the circuit this morning and it is all up and running. The existing 16A MCB will be replaced by a 20A one tomorrow.

Many thanks to all the contributors for for their advice. It is much appreciated.