Xpelair oddly connected

[securespark]

Called out today to quote for replacement CU.

Had a good look round as I always do, and amongst other things found this:

A 30A cooker circuit feeding an MK CCU with socket outlet. The only difference being that the cooker switch feeds an Xpelair. The socket feeds a kettle.

Everywhere is beautifully decorated. How can I make this set-up comply?

 

[Inspector]

Is there also a cooker supplied from the switch or just the fan?
Is the size of cable from the CU to the cooker switch and the link to the fan >4mm?
Has the ext fan a fused spur unit in-circuit (with correct fuse size fitted)?

 

[securespark]

Just a fan fed from the cooker switch, and a kettle from the socket.

CU- CCU = 6mm2

CCU- FAN =1.00mm2

NO FCU.

 

[Big_Spark]

If you reduce the breaker to a 16A 30mA RCBO it will comply.

 

[securespark]

FW-

Without any futher means of fusing down for the fan?

 

[Big_Spark]

FW-

Without any futher means of fusing down for the fan?

No need, In an ideal world you would, however fans are often put on lighting circuits which routinly have 6 and 10A MCB's on, a 16A 30mA RCBO give the circuit all the protection it needs, when fans fail, no MCB or RCBO will prevent the death knell of the unit, which is the only way a small fan would overload a breaker anyway, and as they are double insulated do not pose a significant shock hazard under normal conditions.

 

[AdamW]

But should a switch labelled "Cooker" really be switching on an extraction fan? Just a thought.

Seems a bit dodge to me, I wouldn't want to buy a new cooker only to find out that the fan is wired into the outlet already. Quite likely that the next owner may disconnect the fan to install an electric oven and thus break regs on the gas boiler that might be sitting in that kitchen.

Baaaaaaaaaad design!

 

[plugwash]

i think the best simple fix (though it would involve some decor distrubance in the kitchen) would be to replace the cooker unit with a socket and fcu (for the fan)

if you do this it would be a good idea to downrate the breaker to 16A but not esssential

 

[AdamW]

Yes, you could replace the back box with a double accessory box. That will be one sturdy radial!

 

[Big_Spark]

But should a switch labelled "Cooker" really be switching on an extraction fan? Just a thought.

Seems a bit dodge to me, I wouldn't want to buy a new cooker only to find out that the fan is wired into the outlet already. Quite likely that the next owner may disconnect the fan to install an electric oven and thus break regs on the gas boiler that might be sitting in that kitchen.

Baaaaaaaaaad design!

Adam, Even with a cooker connected to this circuit, the 16A RCBO would still hold up as most Ovens are rated at about 11 to 12.5A today. The Fan will be rated at about 30W and thus is not a significant draw on the circuit. It would be expediant to re-label the switch, but there is nothing electrically unsound in the circuit, nor is it a breach of the Regs.

It may not be IDEAL DESIGN, but if the walls cannot be disturbed, there is little choice.

 

[plugwash]

i see you said oven he said cooker

standalone single ovens don't draw much
double ovens draw quite a bit but not a huge amount
hobs and combined oven/hobs draw a lot!

 

[Big_Spark]

Plug, the thing is we could all second guess what will happen to any installation all day, but then we would get not work done. You can only deal with what you have and what you know, afterall, X-Files is just a program

 

[kendor]

It's not the Fan on the 16amp mcb that worries me as much as the 1mm2 cable being properly protected for overload!

 

[AdamW]

Obviously a fan won't be drawing 16A (although I have done some work with wind tunnels that draw just a little bit more ).

I was just thinking it would all be a bit Mastercard, you know, "finding out the blender still works"... Perhaps I should spend less time watching telly and more time finishing my bathroom

I just thought it was a bit odd about using the existing cooker switch, I wasn't so concerned about the electrical regs as any ventilation requirements for gas appliances... I thought people only install fans (as opposed to extractor hoods) when they have a gas boiler in the kitchen. Hence my concerns about someone coming along later and saying "What's these wires here then? Just remove them and wire in the oven."

I personally would use Plug's suggestion on replacing the cooker switch, that's just my preference though.

 

[plugwash]

that cable size is an issue too

what size is the cooker control unit

if it is the size of a normal double socket you could replace it with a single socket and fcu without too much disruption to decor and i think that is the best way you can get recessed boxes that take 2 single plates for
this you sill need to widen the hole a bit and make the existing part shallower (probally with readymix morter or similar) but if you are carefull you sould be able to do wit without too much decor damage

ie
20A breaker----existing 6mm cable---single socket---new 2.5mm cable--fcu-existing 1.0mm cable-fan