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Topic Title: Switched Neutral in Xpelaire XIM100+T bathroom extract fan
Topic Summary: is functional switching of the neutral permitted or desirable
Created On: 23 July 2013 04:05 PM
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 23 July 2013 04:05 PM
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graham mcgregor

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Joined: 29 January 2009

I recently got involved in a discussion with Xpelaire regarding the control of one of their extract fans, model XIM100+T.

Their control drawing indicates that the run on timer signal is infact a neutral switched through a separate switch as opposed to the conventional looped switchwire from the light switch.

it makes it completely impractical to install in most domestic wiring situations without using an additional switch which switches a neutral conductor.

Regs 530.3.2 and 537.5.1.2 would seem to forbid the use of a single pole switch in the neutral line as a switching device, but Xpelaire seem to disagree.

does anyone else have any experience of this?
 23 July 2013 06:19 PM
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Isn't the neutral switch for speed control not the timer run on - ie the neutral connects via a two way swich to either of two terminals but not both.

This sort of thing has been common on many fans for years from memory

Personally, I don't like it, but given the DP switch up front anyway, and the two way action with no centre off of the neutral, I'm not sure it's a real breach of BS 7671 to be honest.



Let the wind blow you, across a big floor.
 24 July 2013 10:17 AM
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Instructions seem muddled to me: Looking here:
The 'Diagrams' tab give a wiring diagram which seems to show a S.P. switch for 'on/off' connected between the "T" terminal on the fan and N. (fig 8) The fan having terminals marked N/L1/L2/T.

The operating manual on the downloads tab though seems to think the terminals are marked L/N1/N2/T and shows the on/off switch connecting the T terminal to L (if before the fuse?!).

I suspect, being a simple a.c. device, that the fan itself doesn't care if L and N are reversed just as long as power is supplied between the bottom terminal and one of the 1 or 2 terminals and the T terminal is momentarily connected to the bottom terminal to start it.

So it looks like the fan could physically be wired conventionally (with a switched L) - but maybe someone had a bright idea of switching things around so that a single fuse could be used?

You'd think that xpelair would want to sort this out properly - the web reviews (on Screwfix and others) are pretty off-putting.

- Andy.
 24 July 2013 06:26 PM
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I live in hope that the fan manufacturers will eventually get rid of the silly requirement to install a 3A fuse in the fan circuit. This can only be to protect the fan.

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