Exactor fan advice much appreciated...

[abone]

Hi,

I am installing a new extractor fan in our bathroom (in Scotland).

It is a timer and humidistat fan and ideally I would like the fan to be able to run on even when the light is off, so it needs a live, a switched live and a neutral.

The light wiring is quite old and only has three wires at the fitting, switched live, neutral and earth.

It is not possible to get access to the permanent live of the lighting circuit without major demolition.

My question is, can I wire up the extractor fan using a live and neutral from a socket ring circuit (which is easily accessible in the loft space) and take the switched live from the lighting circuit? (I am not joining up the neutrals of the different circuits and the only place where the lives could meet is in the fan electronics.)

I have set it up this way and it works, but not sure if this would be frowned on. If it is not an approved way of wiring it up I would be really interested to understand why.

Many thanks!

 

[AndyPRK]

Can't you get access to the switch in the loft ? That would have the live.

 

[Taylortwocities]

My question is, can I wire up the extractor fan using a live and neutral from a socket ring circuit (which is easily accessible in the loft space) and take the switched live from the lighting circuit?

No! Not only would itr be dangerous (two lives from different sources at the fan), but any RCD in your consumer unit would trip as soon as the fan turns on.

Your option is to do the thing you don't want to do, it needs a new cable to the fan. Sorry.

 

[PrenticeBoyofDerry]

Your other option would be to decommission the lighting circuit within the bathroom, any unwanted cable would need to be electrically isolated and removed if possible, if not possible to remove electrically the ends must be safely terminated in insulated accessible boxes or a maintenance free method used. Then you could use the supply source from the loft space to power the bathroom light and fan. I assume the equipment has been correctly cabled, fused and has 30mA RCD protection.

 

[Taylortwocities]

There will be a permanent live for the lighting circuit at the light switch (and probably the other light switches in the rooms near the bathroom.
Also, somewhere, there may be a large junction box for the lights - there will be a live there too.
(My assumption is that you do not have a loop-in system because there is only swLive, neutral and earth at the light fitting.

 

[AndyPRK]

Is the wiring in conduit?