Spur off 45A cooker switch?

[2997V8]

Nearly finished kitchen install after ring main and 10mm supply to cooker switch and connection box all fitted by electrician (which I'm not, just a DIY mechanic etc)- then realised I didn't allow for supply to cooker hood...

The easiest (or only) way to do this without tearing down cabinets & into plasterwork/conduits would be to run a 2.5mm cable off the switched side of the 45A cooker switch, feeding it back up the wall inside the conduit, and exiting higher up).

Cooker hood instructions say to hard wire its flex to a suitable DP switch (not 13A plug top) and just specifies 240v. If I link the spur from the cooker to a suitable switch, would there be any issues with cable load or power at the hood - apologies if this is basic but I'm happiest with spanners!

 

[phatboy]

Yes, it wouldn't be acceptable - you need to continue at least 6mm cable from the cooker switch. If you can possibly fit 2 cables into the terminals, you could use a 6mm cable, to a FCU, then fit a 3amp fuse and reduce to 1mm T&E

 

[mbga9pgf]

We did this, but dont forget an MCB/fuse of a suitable rating in an enclosure prior to reducing CSA to protect the cable, in the event the cable is damaged and you get a LN fault. Its not good enough (IMHO) to rely on the fuse in the appliance or fused switch to protect the cable.

 

[OwainDIYer]

It may be permissible to use 2.5 from the cooker switch to the FCU. The MCB provides short circuit protection and the downstream FCU provides overload protection.

However, will the cooker switch terminals accept 10mm+2.5mm with firm connections to both wires?

 

[ban-all-sheds]

What is the rating of the MCB for the cooker circuit? Will it actually provide adequate fault protection for 2.5mm² ?

 

[mbga9pgf]

What is the rating of the MCB for the cooker circuit? Will it actually provide adequate fault protection for 2.5mm² ?

If it doesnt, the cable will...

I just about managed to fit 2X 6mm cables in the cooker outlet, only downside is the cooker switch now turns off the oven as well. One 6mm goes to t'cooker, other t'oven MCB enclosure (inside integrated oven cupboard) to a 16A rated MCB (protecting 2.5mm cable, accounting for elevated temp inside cupboard).

 

[Taylortwocities]

There is nothing to stop you powering the fan from the lighting circuit. Most bathroom fans are like this!

The lighting circuit is in the ceiling, and usually that is where the kitchen fan is.

May be an option?

 

[2997V8]

Thanks for the replies guys, I've been reassured then concerned by all this and now unsure if it's OK or not

The new consumer unit has a B32 MCB protecting the feed to cooker switch. The hood that I ran the spur to is double-insulated (so earth not connected) and pulls 87W in total (80w fan, 7w low energy lamp).

Forgive my ignorance (may sound laughable to electrics experts ...) will the cable or appliance be overloaded with the current? The hood instructions just talk about wiring to an 'all pole disconnection switch with contact separation of at least 3mm' and 'a switxched fused connection unit'

Much appreciated