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Extractor fan wiring to ceiling rose

Postby dazmaul » Sun Apr 29, 2012 12:05 pm

Hi, hope some one can help.

For decorating purposes I disconnected the extractor fan in my bathroom from the ceiling rose BUT cannot for the life of me work out how it needs to be wired to get it working again.

What I have is a ceiling rose (as standard, in, out, switch, light flex, etc - all wired correctly).

The Extractor fan is a Greenwood Airvac TX100DT and has three wires coming from it L, N and L1. This was wired into a 13A fuse plate (also disconnected) which then connected to the ceiling rose via two cables, one of which has wires L, N and E, the other has just the L wire (which I believe is because the Extractor fan needs a connection for the timer to operate).

What I need to do is:
Connect Extractor fan to fuse plate (which has IN (L,N) and LOAD OUT (L,N) as well as earth connections
Then connect fuse plate to ceiling rose

I have attached an image which maybe explains it better.

Any help much appreciated.

Bathroom Extractor fan wiring
bathroom.jpg (13.02 KiB) Viewed 10676 times
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Postby ericmark » Wed May 02, 2012 11:51 pm

There are two ways to connect an extractor fan with run on timer.
1) Use a triple pole isolator and rely on the lighting MCB or fuse for protection.
2) Use a FCU and a double pole light switch. In which case there is no connection between the fan and lights.

The first method is only suitable where the room does not have a window or does not require a fan by law. It also is a problem where the fan manufacturer states use a 3A fuse although likely using a 6A MCB is not really a problem.

The Part F (think that the one?) regulations say if you not have to switch on the lights i.e. there is a window then to use the lights as only means to switch on the fan is not good enough so one has to fit a push button to start fan manually as well. Unless one is going to use relays then only way is really the double pole light switch.

However there is no need to use the lights so a pneumatic push button is really all that is required. Plus likely an isolator with a fuse. All bathroom electrics must now be RCD protected so if there is no RCD in the consumer unit then a RCD FCU would be required.

Many fans were fitted with three pole isolators in bathrooms controlled just by lights. But because the window will open no fan is in fact required so it does not need to comply with the control part of Part F. However there is also a bit about where the air is replaced from as there has been problems where fans which of course includes kitchen and even a tumble drier have resulted in flue gases being drawn back into the room because of lack of enough air to replace that pumped out.

It seems you have a mismatch of both systems.
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