Bathroom PIR & Fan with a timer

[travispuk]

Hello everyone.

I am looking to replace some bathroom lights for rated downlights, GU10 LEDs, including some IP65 ones for above the shower area. I want to not have the old string switch and instead use just a PIR in the room.

I have a fan isolator outside the room which is triple pole.

My first question is do I need to have an isolator switch outside the bathroom for the lights also or is it fine just to have the PIR as the switch, ie do I need an override switch?

Also, I have read here that some people who have the fans connected to the lighting circuit and use a PIR also have some issues because of the noisy switching of the fan. Does anyone have any advice or thoughts on that?

With the wiring of the fan, do I use the switched output from the PIR to feed the live (L1) for the fan isolator?

I guess the other final question is can anyone see any issues with the above plan or recommendations?

Thanks in Advance.

 

[ericmark]

From what you are saying you are asking what is allowed so first point is Part P building regulations mean it is more expensive to DIY to within the rules than have a scheme registered electrician do the work for you.

Other parts of the building regulations also come into play I think it's Part F for fans which talk about how triggered. Although you can where either a fan is not required or where there are no windows use the lights to trigger the fan. However where there may be times where the lights are not required then another method (could be as well as lights) is also required.

The regulations as to isolators is again complex and often they are not strictly required but fans, timers and PIR's do fail and not to have isolators would be a little silly. Should the lights PIR fail then one would want to be able to switch off the lights without switching off all lights. The same applies with the fan.

Clearly if lights always work as one walks into the room then the same PIR could run lights and fan.

There are other aspects of the regulations which can become a problem including all items in a bathroom now need RCD protection so what seems a simple job can when following the regulations snowball into a much bigger job.

Remember I am talking about following the regulations to the letter I can't really comment about breaking regulations or law. Likely first step is to get a quote from a scheme registered electrician then consider if really worth paying the £100+ fees vary from area to area to DIY.

 

[travispuk]

Thanks for the reply Eric.

The bathroom is already fed via an RCD. The previous extractor fan was run from an isolator and controlled by the lighting pull cord switch.

My main question is that I am effectively replacing the pull cord switch with the PIR and whether it would be wise to also provide as an isolator for the lights. The reason being as you say, the PIR might fail or some other scenario where being able to turn off the whole circuit may be of benefit. Your response would suggest yes it would be wise.

Therefore I would have an isolator for the lights that is fed from the existing light feed. This would then go to the live and neutral of the PIR. The switched live output from the PIR would then go to the live feed on the fan isolator and the new downlights. I would then also have a separate live feed going into the second input on the fan isolator to provide the timed power.