Extractor fans in bathrooms

Hi All

Wonder if you can help?

I am working on a project and creating a new bathroom and en-suite.
In each I need to install a small 4” extractor fan. In the bathroom there will be a shower curtain around the bath for the electric shower so it’s about 2.3m off the floor, in the en-suite it’s the same height but above the electric shower cubical.

My initial research showed that these can be run of the lighting circuit which ran 1.5 (as they’re both timers run 1.5 from this 4 core).

I’m running a split load consumer unit and read that the fans should in fact be protected by the RCD. This means I should really run the power from the ring main and not the lighting circuit. Is that right?

The whole lot needs to be certified when finished as it’s through building regs but obviously want to get it right!

Any help would be appreciated.

Thanks

It can be run off the lighting circuit & this is the best way as the lights operate the fan (!).

The MCB that protects the lighting circuit needs changing to an RCBO (combo RCD/MCB).
Also the earthing & bonding needs to be up to current regs.

Re your

The whole lot needs to be certified when finished

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This will be done by the registered electrician who does the work. It cannot be done "afterwards".

If he is registered then he will do all the paperwork to complete Building Regs requirements for LABC.

Why the split load board if it's to meet current regs (17th edition)? Assuming you're talking a domestic installaltion, all your circuits will need to be RCD protected. So your bathroom lights will also be RCD protected.

PJ

Under 17th ed regs you can run fan from lighting circuit via an isolator switch. As this is a new installation your lights should be from an RCD protected circuit so the fans will be protected also. If you are using a registered electrician he should know all about this if he is to certify the completed installation.

PJComp Thanks

The work is being done by me and the building inspector was quite happy that the work would be certified afterwards.

Yes I know technically it should be done by a suitabley qualified electriction but on small builds this is not practical, what are you meant to do get him to run a piece of cable that takes 20 mins, then get him back when the plastering and tiling is done to fit the fan and switch for another 30 mins?!

The fan will not be triggered by the light swith but swithched on by a seperate fused double pole swith (not sure given proximity this is neccessary but wil run it anyway) and yes the lighting circuit is run through a MCB.

Thanks All

Gonna jump in on the bandwagon here, as I need to extend this question. I am doing some alterations on a property, moving a bathroom to a different area of the flat. Had the building inspector round today, and told him of the alteration work I am planning. I will be getting a call from an electrician that works for the council to talk through my plan in the next few days.

Extending the ring, and lighting circuit is not a problem - nor installing the bathroom fan and light on the same switch. I suspect, depending upon my design, I will need a Low Voltage Fan, and hence a transformer. I haven't bought the transformer yet of course, but I am guessing it sits between the isolator and the fan. i.e. the L1 / L2/ N out goes to the transformer before feeding the fan? Can anyone tell me if this is correct?

doni said:

I will need a Low Voltage Fan, and hence a transformer. I haven't bought the transformer yet of course, but I am guessing it sits between the isolator and the fan. i.e. the L1 / L2/ N out goes to the transformer before feeding the fan? Can anyone tell me if this is correct?

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You'd be better off starting a topic of your own, rather than hijacking someone elses. But we are here now.
When you buy an extra low voltage fan (not low voltage - that is 230V) it will come with the transformer and the SELV fan.
It will also come with a handy leaflet called "Installation Instructions".
You'll just need a pair to carry the 12v to the fan from the tranny. At the transformer you need live, neutral and switched live.