Connecting new circuit to consumer unit for oven & hob.

[SYS49152]

We will be replacing our all-in-one cooker soon, with a separate hob and oven. I was going to use the existing cooker feed for the hob and a new feed for the oven (or vice-versa).

The consumer unit is a Hager with individual fuse holders for the various feeds. It it split into 2 parts, the left side is RCD protected (shower, lights etc) and the right side is for the cooker etc. The only physical space in the unit for a new fuse holder is on the extreme left i.e. next to the RCD circuits.

I suppose it would be better if I included a picture but I don't have one handy. My question is this: if I fit a new 30A fuse holder on the left side for the oven, could I jumper the "feed" for it from the right side (non-RCD protected) live busbar, using a part of the new flex I bought for it? The busbars have been cut/fitted with only enough feeds for the existing fuse holders.

Also, there are 2 neutral connection bars at the top of the unit. Does it matter which one I connect the new flex to?

I'm not a expert on this which is why I'm asking for your advice. There may be a better way of going about this but I thought that a new separate feed was the way to go. I'll try to post a pic if it helps explain this situation any better.

 

[LoveRocket]

Hmmmm. Do you actually have fuse holders rather than circuit breakers? On a split-load board? I know Hager do still make fuse holders for their CUs, but I can't imagine why anyone would have installed them.

Anyway, you need to find out what the power requirements are of your new hob and oven. The hob will probably specify a 30/32/40 amp supply, in which case your existing (30amp I'm guessing) supply will be fine for that. Now when it comes to the oven, this is important - if the manufacturer's instructions say it can be connected directly to a 30/32amp supply, then just connect it to the original feed, (together with the hob). If the MI say it needs a 13a supply, then fit an FCU next to the outlet plate, fed from the hob feed.
If however they specify a 16a supply, you are gonna need that extra circuit from the CU.
If you're gonna bury the cable in plaster it will need to be on the RCD side of your CU. Just get a piece of Hager bussbar and cut it to the size you need, then replace the whole lot on the RCD side. Don't try to run a feed from the incomer or anything daft like that. Make sure you isolate your supply OUTSIDE of the CU when doing this (do you have an external isolator?)

Yes, it is essential that you use the correct neutral bar - if you don't you will trip the RCD every time you turn the oven on.

PS. Why are your lights on the RCD side?
PPS. I think you mean 'cable' rather than 'flex'
PPPS. Read up on domestic electrics, this is serious stuff you're getting in to, so please do it right.


I will now clear the floor for you to be told that you are an incompetent criminal....

 

[SYS49152]

Thank you for your very informative reply.

Yes I do indeed have fuse holders. They were fitted when the house was built around 10-11 years ago.

The (double-under) oven manual states that the appliance should be connected using a double pole control unit of 32A capacity, with 3mm minimum contact separation on all poles. Connection should be made with twin & earth minimum 4 mm sq for use up to 25A. The hob manual states that the supplying circuit should be rated to 32A with T&E 4 mm sq.

The cable has already be installed from the CU (lying loose) to the wall near the cooker. It was fitted by the electrician when the house was built, even though it was never used / needed. Does this still need to be fitted to the RCD side of the CU? The existing cooker feed comes from the non-RCD side.

The only free space I have in the CU is on the extreme left side and the non-RCD busbar is on the right side, so I would have to link the busbar to the new fuse holder with a piece of the new cable (not flex )

BTW it wasn't the lights but the sockets that are on the RCD side

I will get a pic tomorrow to hopefully clarify what I am trying to explain here.

Thanks once more.