Clever electrical scheme

Just replacing a bathroom light fitting. Running from it in the opposite direction to the standard 1.5sqmm T&E supplying it is a single core 1.5sqmm red cable (proper PVC outer sleeve and everything). This connects to an extractor fan, providing a live connection switched by the light switch. The light circuit is part of a 10A light circuit, eminently reasonable so far. However, the fan is also supplied with its only neutral and a permanent live connection from a fused (13A) but unswitched spur off a nearby socket circuit.
Don't ask me how I know, but this is an electric shock risk (fortunately only to parts of one hand owing to good self-training).
Does anyone think this is a good idea?
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Roger Hayter

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On Saturday, 19 November 2016 12:43:21 UTC, Roger Hayter wrote:

It's a very bad idea. There is the possibility in the event of a fault that live can backfeed from the extractor fan if the semiconductor timer circui t fails, to the socket circuit even if the socket circuit is switched off a t source. Someone working on the wiring could easily have full 240V hand-to -hand if only the socket live source was disconnected (MCB opened or fuse p ulled).
Owain
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Yes one should strive to get all connections from the one place not two separate ones as in the future you may not be around to warn them. Personally I do still find having unswitch lives in ceiling roses a bit of a nonsense, but then that is probably just me. Brian
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On 19/11/16 12:43, Roger Hayter wrote:

No, that's not OK.
For one, you are effectively sharing a neutral between two circuits.
And you are potentially sharing the lives if the fan electronics fails in an interesting way.
If you had to do this, using a relay as a full galvanic isolator (relay coil driven by lights, contacts on the socket spur side) would be theoretically OK - but it will still confuse the next person who looks at this.
Can you not pick up a lighting live from somewhere?
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It was a bit of a rhetorical question - I didn't leave it like that!
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Roger Hayter

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On 19/11/16 19:43, Roger Hayter wrote:

Oh - OK :)
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