Connecting a fan to shower power

[tirfor]

Hi all, a newbie requiring advice.
I have been asked to fit a fan within a bathroom with the following constraints:
1. fan needs to work in daylight when light is off.
2. ideally on a timer so steam can be removed after showering.
3. humidistat not to be used as past units did not work to well.
4. be able to use 3a fans.
5. cheap as poss so no expensive fans or expensive pir's

So i have thought it would be best to connect the fan to the showers power.

My question is:
1. Is this ok to do or is there a better idea?
2. A timed fan requires a live and switched live, so is a fused spur available with twin fuses?
3. My idea is to tap into the supply side of the shower switch to provide the live feed and then tap into the load side of the shower switch to provide the switched live. Both lives will go to separate fused spurs (located in assessable attic) then both spurs will be connected to an isolation switch (in wall be bathroom door) then of to the fan. Is this ok or am i missing something?

Cheers for your help.

 

[telectrix]

don't tap into the shower. feed the fan from lighting circuit, but with it's own switch, independent of the light. if customer wants it to come on automatically, switch it with a PIR sensor.

 

[R G]

Occupancy sensor is your best bet and cheapest , like Tel says don't tap into shower circuit

 

[ArseyDee]

Fan with integral pull cord switch and timer fed from lighting circuit?

 

[overskilled]

As said above, lighting circuit NOT the shower circuit...
Surprised Glenn hasn't seen this yet......

 

[tirfor]

The fan is being fitted in a rental property and the customer doesn't trust the tenants to turn on the fan so a pull cord option is not viable. A PIR would do the job but the customer suggested that it would keep coming on even if someone just went in to brush there teeth. I did suggest placing the sensor near the bath but a zone 1 sensor was around £60. The customer was also worried that it may break down regular and have a high costs to repair. Hence he rather have a simple system.
Is there any reason why I shouldn't tap into the shower cable as the fan only takes less the 1A?

 

[ArseyDee]

A PIR would do the job but the customer suggested that it would keep coming on even if someone just went in to brush there teeth

Fan unit with a delayed start module may be the answer here.

 

[HandySparks]

Flow switch in the shower supply pipe works for me (on a pumped shower) with timer run-on. Mine's been in nearly 10 years and has just started playing up, so I have the replacement waiting to go in.

 

[guest119]

Single Range AC Current Operated Switches

 

[shanky887614]

Guys why not simply fit a humidity sensor.

Power the fan and humidity sensor off the lighting circuit and bob's your uncle

 

[tirfor]

OK, I have spent all day looking through the regs book and online and can't find any reason why I can't tap into the shower cable. I have seen posts from others stating its not a good idea but nothing to back it up so I can go back to a customer and give them a good enough reason why it cant be done.
When I say I am planning to tap into the shower cable, I mean using 60A junction boxes with 6mm cable continuing to the 3a fused spurs then 1.5mm to the isolation switch and fan.
Does anyone know why it cant be done? I was going to sign it off but now I'm thinking I've missed something from the regs.

 

[MDJ]

OK, I have spent all day looking through the regs book and online and can't find any reason why I can't tap into the shower cable..

Because it is a crappy DIY method, I would never consider doing it.

 

[guest119]

Saw it before with a 5a mcb inside the shower unit tapped off the low (always comes on) element.
1.5 te out to a spur, 3a fuse and the fan ran when the shower was on.

Boydy

 

[MDJ]

I mean using 60A junction boxes with 6mm cable .

Gasp.....

 

[LED Lighting]

I understand what your saying with regards to the landlord. Some tenants are very stupid!
use a 1.5mm cable from shower supply (prior to iso) to FCU (3A) to permanent supply of fan.
a 1.5mm cable from shower supply (after iso) to FCU (3A) to switched supply of fan.

personally a PIR would be better and just as cheap!
2 FCUs including the fuses would not far off be the same price as a recessed PIR. I'm picking these up for as little as £5 each!

 

[Zebra Stripe]

Christ, tell the client it requires a PIR sensor, it will cost this much, if he's still not happy tell him you'll stand in the shower room all day holding a big feather and promise to swoosh it up and down when someone comes in....charge £2.50 per hour for the swooshing..good luck..
p.s dont think its a good idea to have 2no separate FCU as you suggested, as I think you'll then have a borrowed neutral on load side

 

[Spearmint]

Because it is a crappy DIY method, I would never consider doing it.

Agreed. What if there's already other loads on the circuit even though there shouldn't be? If you're working above the lighting circuit is ideal. As others have already mentioned... FCU from lighting circuit with 1.5/1mm².

 

[tirfor]

I can see its not ideal but still can't get my head around why it wouldn't be safe and follow the regs????????

"p.s dont think its a good idea to have 2no separate FCU as you suggested, as I think you'll then have a borrowed neutral on load side"

Would this be a problem as I thought as the neutral is from 1 circuit it is ok?

 

[Spearmint]

So it's safe and follows the regs?

Safe? What's the total loading on the circuit and can the 6mm²(?) cable handle the extra load after taking into consideration the installation methods? You're trying to avoid cables melting here, use the lighting circuit.

 

[Zebra Stripe]

My question is:
1. Is this ok to do or is there a better idea?
2. A timed fan requires a live and switched live, so is a fused spur available with twin fuses?
3. My idea is to tap into the supply side of the shower switch to provide the live feed and then tap into the load side of the shower switch to provide the switched live. Both lives will go to separate fused spurs (located in assessable attic) then both spurs will be connected to an isolation switch (in wall be bathroom door) then of to the fan. Is this ok or am i missing something?

I beleive what your suggesting here would ineffect create a borrowed neutral situation as both OCPD (the fuses on the switched & unswitched) would be sharing the same neutral and as such would not comply and be rather dangerous IMO