Extractor fan twin and earth question

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My electrician has messed up and mistakenly fitted a twin and earth from the isolator instead of a 3 core and earth. The extractor fan has L, and S/L. He's suggested that he'll wire S/L directly into the extractor fan from the adjacent downlight and will thoroughly label the extractor fan that it has a dual supply.
He's obviously trying to save costs not to chase another cable.
Can someone please advise if this would be a safe way to remedy the situation?

Thanks in advance
 
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The best thing to do is to fit a low voltage fan, and fit the transformer next to the fan isolator.

Low voltage fans only require two cores, as the timer unit is within the transformer.
 
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How many times have we seen this question...

Solution: Take the timer circuit board out of the fan housing and fit it in an enclosure at the origin of the T&E / accessible place.
 
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No, as you would have an isolator that doesn't isolate.

'Isolator that doesn't isolate' seems pretty common on early 1990s jobs, I presume as timer fans started to become standard and 3 pole fan isolators were uncommon/expensive/not known about? (looking for pointers here - before my time) and you have a MK logic switched fused spur with live and neutral going through the spur, and switched live jointed with a 5A connector block in the back.
 
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There is a difference between the meaning of words as used in everyday English, and when used as technical terms by professionals among themselves.

In the same way that, botanically, a tomato, a cucumber or a banana is a berry, and a strawberry isn't. Nor is a raspberry.

Professionals with a brain bigger than a flea are aware of this and can understand ordinary people speaking ordinary English.

Only a numbskull like Winston would order "fresh berries and ice cream" in a restaurant and then spend days complaining that it contained no tomatoes or cucumbers.
 
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There are ways around the problem, but an isolator for three core is different to the one for two core, and if simply he picked up wrong reel of cable, the question is does it really need three core or is there another method?

We have seen this with borrowed lines with two way switching, and by using a wireless linked switch we can get around the problem, Quinetic switches are not cheap, so there is a balance between pull in a three core and use electronics.

In the main we worry about the borrowed neutral, in most cases actually the line is borrowed, but it means you can get current on a neutral wire which should not be there.

Using extra low voltage or in USA it is called low voltage, means the borrowed neutral does not cause danger, because USA will not conform there is a problem with the term low voltage, which most countries except for USA think as being 50 - 1000 volt AC. But since stuff is sold to both USA and other countries and the citizens of USA seem to be lacking common sense, and love to take things to court, often packaging has USA labels, in general rest of world not as pedantic as them.

Bathroom rules have it seems changed a bit, originally in a room with non opening window it was required to turn on fan without turning on the lights, this seems to have been dropped, but there is nothing to say lights need to be connected to the fan, you can have for example a pneumatic switch which when pushed runs the fan for 15 minutes.

As one point we were using two pole switches in bathrooms so we could turn the fan on independent to lights.

The PIR was another option, this ensured fan always runs when bathroom is used.

Two reasons for a fan in a bathroom, one smells, the other water vapour, but to work air also needs to enter the bathroom, I have seen vents in the door to allow air in, but it depends on the temperature of the area other side of door, using a heat recovery unit upload_2022-4-10_12-15-41.png gets around the problem of replacement air. OK £180, but although a door vent upload_2022-4-10_12-18-51.png is far cheaper, may be £9 you need some one to fit it, so looking at cost of job not cost of items used to do the job.

Be it extra low voltage, or a system which only needs twin and earth, or replace the cable, or even use a PIR or timer switch it is some thing for you to agree with your electrician.

Last house shower was in the bath, glass doors around shower, but room above and below the shower doors, so air circulated, and room filled with steam, this house shower doors seal at the bottom, so air does not circulate and room stays dry. So in this house the extractor fan is never used.

Same with mothers house, wet room and because no shower curtain or door, there was no chimney effect, so steam did not seem to fill the room, and the fan was never switched on, mainly as it sucked in cold air from the hall, and with a sliding door it was left open when room not in use, so room naturally dried.

The LABC inspector insisted on a fan, as he said even when windows could open, people could see in from the drive, so needed extractor, once the completion certificate was issued it was switched off never to be used again.

But my house did not have a fan and needed one, due to the shower doors causing the chimney effect. Never a problem with just a bath, it was the shower which caused the problem.
 
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Hi All,

Thanks for all the replies and advice. The extractor fan has some sort of a humidity sensor in conjunction with a timer. I'll be asking for a new cable run.
 

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