Oven Circuit Question

[1strangefish]

Morning All

I am installing a 6mm T&E circuit on a 32amp MCB (on an RCD protected board) for a 3.5kw Bosch oven. The 6mm is going to a 40amp dp isolator. The oven has a factory installed plugless prewired cable. How do I ensure that the oven cable has adequate protection?
By this I mean that Bosch would only have supplied cable to cover the oven requirements (so to a max of 20amps), MCB covering my circuit is 32amps. I know its right but I can't help feeling its wrong!

Thanks
Fish

 

[Sintra]

There are 2 things you could do. Either change the mcb to a 20A or rely on the fact that the 3.5 KW is a fixed load so it can't overload the cable.

 

[HappyHippyDad]

Would you be happy with that Sintra? By that I mean the supplied pre-wired cable is probably going to be 2.5mm, so its a 2.5mm cable protected by a 32A MCB. I guess its no different to a spur off a ring though. Pity they dont make 20A fuses for a FCU, although there must be a reason for that otherwise they would!

 

[DPG]

Would you be happy with that Sintra? By that I mean the supplied pre-wired cable is probably going to be 2.5mm, so its a 2.5mm cable protected by a 32A MCB. I guess its no different to a spur off a ring though. Pity they dont make 20A fuses for a FCU, although there must be a reason for that otherwise they would!

FCUs are only rated at 13A, that's why you can't get a bigger fuse for them. Daz

 

[Risteard]

Would you be happy with that Sintra? By that I mean the supplied pre-wired cable is probably going to be 2.5mm, so its a 2.5mm cable protected by a 32A MCB. I guess its no different to a spur off a ring though. Pity they dont make 20A fuses for a FCU, although there must be a reason for that otherwise they would!

You only need fault protection and not overload protection though, so the 2.5 will be fine.

 

[Darkwood]

The Oven factory fitted flex is outside the scope of the BS7671

430.1 -- note 4 kinda covers this but been factory fitted it can handle the max current demand of the oven, the mcb is protecting the 6mm not the cooker flex.

 

[Sintra]

Would you be happy with that Sintra? By that I mean the supplied pre-wired cable is probably going to be 2.5mm, so its a 2.5mm cable protected by a 32A MCB. I guess its no different to a spur off a ring though. Pity they dont make 20A fuses for a FCU, although there must be a reason for that otherwise they would!

Yes I would. Others have explained why.

 

[Engineer54]

FCUs are only rated at 13A, that's why you can't get a bigger fuse for them. Daz

Well i've seen and have actually purchased 15A BS 1361 fuses in Cyprus. I've also come across them in quite a few other countries too!! lol!!
Coloured black with white writing, if i remember correctly!!