Connecting a fan to shower power

tirfor · Jan 12, 2014

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.

D Skelton · Jan 15, 2014

A fused spur from the light circuit, then to a flow switch on the shower supply. From the flow switch you can take a P/L, SW/L and N to the fan.

ChrisElectrical88 · Jan 15, 2014

This thread is daft.

tirfor · Jan 15, 2014

D Skelton said:
A fused spur from the light circuit, then to a flow switch on the shower supply. From the flow switch you can take a P/L, SW/L and N to the fan.

This sounds like a good idea, only problem is the bathroom is in a finished state so would be very heard to run wires and get to the pipework. But defo an idea for future jobs. Thanks.

phil d said:
ok if you are determined to go down the route of connecting into the shower here goes,put a current transformer around the live on the load side of switch,connect this to a current sensing relay,then take a permanent live and neutral from the lighting circuit through this to the fan.should only cost about 60 quid but hey ho if that's the route you insist on going down and connecting to the shower.

Another good idea, but like you said how long will it take to sort out:38:.
Just out of interest, if there was a readily available unit which does all that for you (yes with patent and BS standards etc) how many off you would use it when you have a job brief like mine?

I'm looking into good quality humidity fans and a 3A fused isolation switch, this will be my last resort.

I'm still surprised why nobody can explain why a showers power supply cannot be used to run a fan as well if all is within tolerance levels. All I have seen is its a daft thread and a DIY job but still no answer. Come on then help me end this thread with an appropriate answer???????????

MDJ · Jan 15, 2014

tirfor said:
Wow! I never knew dummy spiting kids worked in the electric trade :rolleyes2:

Please do not comment on this thread unless you can be helpful and explain why certain ideas cannot be used with backed up evidence. Rather than just ranting on.

Thanks to all who have suggested why my original idea may not work due to the neutral. I’m still looking into that.

But I still haven’t had answers on why the shower circuit can’t be used as a power supply for another circuit and the use of junction boxes, even if the total current load is within the cables tolerance as per regs book?

Just too clarify, yes I can take the easy option of a humidity sensor or pir but as stated it does not solves the job brief. Ie past humidity fans fitted can be temperamental and a pir will cause the fan to run pretty much all day. If someone gives me a problem I like to try to solve it so they are happy, don’t you guys?

Thanks for the idea of a fan with a built in pir and timer, but the original fan hole is already at the far end of the bathroom where someone will not be able to walk past it in order to set it off. Making a new hole is not an option.

Thanks for the 3A idea, ie the lights circuit into the bathroom. Although this does solve the problem of using 3A fan it does not solve the problem of having the fan only work if the shower is in use.

What about the idea of a switching relay, anyone done it before?

:mad2: So you think cutting into a 6mm2 cable which is controlling a shower and adding a Joint then teeing off it for a fan is pretty cool? I would avoid at all costs interference with a conductor feeding a shower, I expect others who were trained properly like myself over a period of years under a professional mentor would think so to. As your other question regarding the relay, IMO you are totally over complecating a very very easy job, why go to all the bother of this, were talking about a fan in a Domestic bathroom not a door entry system which is fed via relays on a fire alarm system. Tell you customer to have a plain simple PIR controlled fan fed from the lighting circuit, you could have it on a pull cord or on a timer, but fed from the lighting circuit and not the Flucking Shower feed, comprende.

tazz · Jan 15, 2014

Dear Guinness Book Of Records.....I would like to claim the record for the longest thread ever posted on a UK forum......
Yours Sincerely
TAZZ

DPG · Jan 15, 2014

tazz said:
Dear Guinness Book Of Records.....I would like to claim the record for the longest thread ever posted on a UK forum......
Yours Sincerely
TAZZ

Apart from the rewire one a week or two back! Daz

tazz · Jan 15, 2014

Don`t forget the 32a ring main....!! DPG

MDJ · Jan 15, 2014

shower feed, shower feed :mad2::mad2::mad2::mad2::mad2::mad2::mad2::mad2::mad2::mad2:

Geordie Spark · Jan 15, 2014

He'll do it HIS way!

(with apologies to the late, great Frank)

Frank Sinatra Live in London 1971 My Way - YouTube

Badged01 · Jan 15, 2014

MDJ said:
... trained properly like myself over a period of years under a professional mentor .....

Called knocking-shops in my day ..... :lol::lol::lol:

tazz · Jan 15, 2014

How abaut a selectable current sensing Din mounted relay in the Cu.....The L from the shower passes through the relay and the current measured switches on the fan. Safer than tapping into the isolating switch or shower

[ElectriciansForums.net] Connecting a fan to shower power

Badged01 · Jan 15, 2014

Why not just open the window like we used to do when I was a kid? That was after we had moved up from the tin bath infront of the coal fire! My mum was posh like that .....

tazz · Jan 15, 2014

Badged01 said:
Why not just open the window like we used to do when I was a kid? That was after we had moved up from the tin bath infront of the coal fire! My mum was posh like that .....

Those were good days.......if you ask the OP nicely....he may fit a immersion heater in your tin bath for you.....and bond it...!!!

MDJ · Jan 15, 2014

tazz said:
Those were good days.......if you ask the OP nicely....he may fit a immersion heater in your tin bath for you.....and bond it...!!!

:lol::lol::lol: Love it

Guest55 · Jan 15, 2014

the comedy value of this thread is staggeringly good

anywho , theres no point in taking a fan feed from the shower supply if the the shower is switched on and off at the shower rather than at the pull-cord , regardless of everyones demented interpretations of bs7671 , as it will just run all the time.

the only alternative i can think of is a nuclear powered flux capacitor actuator linked to a laser detection grid.
or maybe just open the window , which seems to have worked fairly well for the last 50 years.......
;-)