Wiring Extractor Fan

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Hi all,

I need to wire up the extractor fan in our new downstairs bathroom, it has a timer run on as opposed to a humidistat.

The simplest way would be via the light switch as is fairly standard but I want to avoid this method as the bathroom is below the main bedroom and I can already picture the wife moaning about it being switched on at 3am.

Ideally I'd like it wired via the shower switch which is a 50a double pole switch wired with 10mm t+e to a 9.5kw shower.

My understanding of this is its not straight forward as you'd use 1.5mm t+e for the extractor which obviously isn't protected by the 40a mcb supplying the switch so how would I go about making this setup work?

Thanks
Chris
 
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You can get fused connection units (FCU) to fuse down the supply, but the basic requirement is it must run on, if no opening window, but can be controlled by a simple switch.

The pneumatic push button seems good way, but the main reason for an extractor fan is to satisfy the LABC inspector, who can some times be a pain in what they want.

I used the lights with mothers wet room, and a triple pole isolator, and once the inspector passed it all was switched off, and rarely used again. Note the one linked also has a fuse built in.
 
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An fcu would work but leaves me with the issue of trying to get 3x 10mm t+e into the first switch neatly, getting 2 pairs in is enough of a pain
 
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The simplest way would be via the light switch as is fairly standard but I want to avoid this method as the bathroom is below the main bedroom and I can already picture the wife moaning about it being switched on at 3am.
Buy a good quality modern fan with a ball-bearing motor and rubber mounts.
 
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Ideally I'd like it wired via the shower switch which is a 50a double pole switch wired with 10mm t+e to a 9.5kw shower.
No. That is an isolator not a switch and is for isolating for maintenance. It does not and should not be turned on and off every time you use the shower.
 
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Your allowed to use up to 3 meters of cable to the fuse of the value to match fuse if protected from mechanical damage. It does not need to be 10 mm² to the FCU from isolator.

That's ideal and something I didn't know
 
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No. That is an isolator not a switch and is for isolating for maintenance.
I assume the isolator switch is something like either of these:
and the titles of both of them include the word switch as they are switches and operating them switches the power on or switches the power off.
It does not and should not be turned on and off every time you use the shower.
When was the last time you saw a rotary switch used for a domestic shower to be able to turn the power on and off?
Why do you say the shower should not be isolated when not in use?
In my opinion it shoud be, we always isolate ours and always have done since fitting our first in mid 70's, apart from anything else it saves wasting power (currently ~3W or £15/year in our case) when not in use. However the main reason, in my opinion, is shower units are far from reliable units and failure of the mechanics, microswitches and electronics is far from uncommon often resulting in flooding or over heating and in one case I know of fire gutting the floor above the shower.


One example:
https://www.diynot.com/diy/threads/shower-isolator.595585/
at todays prices 3500KW of energy being circa £2K and 300m³ of valuable drinking water circa £900. seems to be an expensive mistake to me.
 
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It's that one to be exact, being mounted next to the light switch as you first enter the room well away from the zones.

I hate the pull cord type with a passion.

As for use, apart from the next 6 weeks where the bathroom in question will be the main bathroom whilst I sort out the new upstairs bathroom, in the medium term future the shower in the downstairs bathroom will see very little use, it's mainly there as future proofing should an elderly relative need to move in as we already have a good size downstairs bedroom so it would remove the elderly relatives need to negotiate the stairs if that time ever occurs, the rooms primary function in our current situation is just a downstairs loo and basin.
 
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When was the last time you saw a rotary switch used for a domestic shower to be able to turn the power on and off?
Never, but has that got to do with it.
Why do you say the shower should not be isolated when not in use?
In my opinion it should be, we always isolate ours and always have done since fitting our first in mid 70's, apart from anything else it saves wasting power (currently ~3W or £15/year in our case) when not in use.
You have a greedy neon in your isolator and a greedy supplier. 3w x24 x365.25 /1000 =23.6kWh. £15/23.6= 63.5pence per unit.
However the main reason, in my opinion, is shower units are far from reliable units and failure of the mechanics, microswitches and electronics is far from uncommon often resulting in flooding or over heating and in one case I know of fire gutting the floor above the shower.
We get far more complaints about faulty shower pull isolators than faulty showers.
One example:
https://www.diynot.com/diy/threads/shower-isolator.595585/
at todays prices 3500KW of energy being circa £2K and 300m³ of valuable drinking water circa £900. seems to be an expensive mistake to me.
Insurance?
 
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That's ideal and something I didn't know
It's not true - if the smaller cable is able to withstand the fault current there is no length limit and the protective device may be positioned anywhere on the cable.

If the cable cannot withstand the fault current then three meters is the limit and also fire precaution measures must be implemented.
 
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In BS 7671 there is a chart of BS EN numbers and which can be used for switching, isolation, emergency and other uses, in the main looking at the list isolator can be used to switch.

Main diffrence between an isolator and switch is an isolator switches all live wires, including neutral, where a switch only turns the line or phases on/off.

But for DIY this is over complicating it, and I was linking to a fan isolator not a shower isolator, which I and sure can be used daily.
 
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I assume the isolator switch is something like either of these:
and the titles of both of them include the word switch as they are switches and operating them switches the power on or switches the power off.

When was the last time you saw a rotary switch used for a domestic shower to be able to turn the power on and off?
Never, but has that got to do with it.
Just employing your usual preference for pedancy.

apart from anything else it saves wasting power (currently ~3W or £15/year in our case) when not in use. .
You have a greedy neon in your isolator and a greedy supplier. 3w x24 x365.25 /1000 =23.6kWh. £15/23.6= 63.5pence per unit.
OK I lied, we are currently still in a fixed price contract for a couple more months but 23KW per year is still very wasteful and some people are on 70p/KWh

We get far more complaints about faulty shower pull isolators than faulty showers.
So what? It's far easier and cheaper to replace a switch and yes it is a switch and that is what matufacturers list them as than the overheated/burnt shower unit or bathroom

One example:
https://www.diynot.com/diy/threads/shower-isolator.595585/
at todays prices 3500KW of energy being circa £2K and 300m³ of valuable drinking water circa £900. seems to be an expensive mistake to me.
Insurance?
Good heavens, do you really live your life putting in insurance claims in preference to flicking a switch?
It's very likely insurance would put that down to negligence and not pay for the loss of power and water.
It's that sort of fraudulant claim that makes all of our insurances so expensive.
 
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