shower extractor fan

[barrytuvey]

hello

i want to wire an extractor fan off my shower,so when i turn the shower on the fan works. can i take a live a neutral straight from the pull cord that controls my shower bearing in mind i will only be using cable suitable for house lighting.
i have done this and it does work but is it safe?

 

[nstreet]

Not much point asking 'is it safe?' if you have already done the work

 

[pipme]

hello

i want to wire an extractor fan off my shower,so when i turn the shower on the fan works. can i take a live a neutral straight from the pull cord that controls my shower bearing in mind i will only be using cable suitable for house lighting.
i have done this and it does work but is it safe?

I am no expert, but tis unsafe.

I guess you are new here, so go to //www.diynot.com/forums/viewtopic.php?t=7553 The 'UK Electrics For Reference area' and read through .. loads of diagrams etc.

 

[ban-all-sheds]

Is it an instant electric shower, or a pumped "power shower"? I can probably guess given that you mention a pull switch, but it might be an isolation switch for a pump.

 

[spence_spark]

I am "guessing" that you have connected directly from the load side of the pullcord to the fan...in this case it is unsafe as the pullcord will more than likely be fed by a cable that has a fuse / mcb that has a rating of anything upto 50amps(dependent on shower model fitted)((and assuming fitted correctly!!))
as your fan is normally rated to 5 amps(usually) you will see that if it ever develops a major fault the fuse will never blow and hence fan will basically melt causing fire etc ...worst case!


you should de-rate the supply by putting a fused connection unit within the new cable run and put a 5amp fuse in it
hope this helps


spence

 

[andy]

hello

i want to wire an extractor fan off my shower,so when i turn the shower on the fan works. can i take a live a neutral straight from the pull cord that controls my shower bearing in mind i will only be using cable suitable for house lighting.
i have done this and it does work but is it safe?

it is extremly dangerous. id expect the shower MCB/fuse to be about 45A. this will not protect the fan and if there is a fault then make sure you have a fire extinguisher handy

 

[ban-all-sheds]

You can do what you want, safely, but it requires the use of items which are out of the ordinary.

The problem you have to solve is that the cable to the shower is protected by a large MCB - 45 or 50A is not uncommon, but even a small shower is likely to be 40A, and that is way too big to protect the 1mm² or 1.5mm² cable you've used for the fan. If you could wire to the fan in 6mm² or 10mm² then you'd be OK, but you'll struggle to get 2 cables that size into the terminals of the switch. So you end up needing some kind of junction box for the cables, which can be done - TLC sell a 60A JB with terminals that will take 2 x 10mm² cables. Then you need to go from there to an FCU (or two if the fan is a timed-overrun one) in 6/10mm², and then to the fan in1/1.5mm²

I've got just such an arrangement of a fan switched by the shower, but instead of a junction box I used DIN-rail mounted connection blocks and a fuseholder, and a contactor so that I could use the lighting circuit to supply the fan:

It actually didn't get built quite according to plan, as I didn't have enough space on the rail for a block for the fan neutral, but as the contactor was a DP one, I was able to use one of its terminals instead.

Under construction:

(can you spot the deliberate mistake?

)

All installed. No way to get the items to sit upright on the rail:

But when the cover is in place you can't see them.

(The cover, BTW, should have a warning label about it being fed by multiple circuits. I'll stick one on sometime....)

 

[andy]

(can you spot the deliberate mistake? )

yes. it looks as tho u put the blue (neutral ) form the fan on the top of the contactor (and the neutral from the light is in the bottom). which means the neutral is broken when the shower is off and the timer doesnt work

when do i get my award for 'observer of the year'?!

 

[ban-all-sheds]

Spot on - give that man a cuddly toy.

Yup - when I found I didn't have room for the other terminal, I thought "that's OK - I'll use one of the contactor poles."

But I did realise what I'd done before I installed it and found that the timer didn't work....

 

[andy]

Spot on - give that man a cuddly toy.

Yup - when I found I didn't have room for the other terminal, I thought "that's OK - I'll use one of the contactor poles."

But I did realise what I'd done before I installed it and found that the timer didn't work....

at a school a few month ago i done a similar thing (actually it was the electricians idea, but no1 realized at the time). there was a wire coming to a DP switch then to the light. there was a switch on the other side so i took a single brown between the switches and a single brown to the light (this side was only SP). we then took a single blue to the other light. turned on power. light from DP switch worked. light from SP switch only worked when other light was on.

solution to above? jam all neutrals in the same terminal. the specs didnt say i had to be DP

 

[OwainDIYer]

(can you spot the deliberate mistake?

Contactor coil fused at 45A?