Why 3 Pole for Fan Isolator Switch

[RzB]

I'm intrigued as to why a Fan Isolator is three pole?

See...

is that?

Thanks, Roy

[Christian McArdle]

You need to isolate neutral, permanent live and switched live.

The isolator is intended for fans that are switched by the light switch, but have an overrun timer. A device that doesn't use the light switch, such as a separately switched or humidistat unit does not normally need a 3 pole isolator.

Christian.

[Andy Wade]

Because in the case of bathroom and loo fans there are usually three lines requiring disconnection to completely isolate the fan:

- permanent live (enables run-on under timer control, also for PIR or humidistat controls, where fitted),

- switched live (from light circuit, brings fan on with light),

- neutral.

[RzB]

Ahh - I see - It's not to switch the earth then... :-)

Many thanks, Roy

[Owain]

Ah now, did you bond the pattress box to the supply or the load side of the earth switch?

Owain

[The Natural Philosopher]

Why not shove a double pole IN FRONT OF the light switch..

[John White]

You might be in a bathroom without a window and need to see so you can clean the fan.

Isolating the three wires for the fan allows the light to function normally.

John

[gort]

Do we smell a dodgey circuit then....

Dave

[RzB]

No, no - not at all - I just happened across this item whilst searching for other stuff on TLC and thought to myself - wots that for... Hence my question.

The "earth switching" was my poor attempt at humor :-)

My bathroom doesn't have a fan - yes yes - I know...... but that's after the kitchen refurbishment!!!!

Thanks, Roy

[gort]

Ah I see, ok

Cheers

Dave

[NoSpam]

[NoSpam]

When you do the refurb think about having 2 pull cords - one for the light over the shower + the fan and one for the rest of the lights. It works well and means you don't have to switch the fan on in the middle of the night unless it's REALLY necessary :-). I also put a dimmer on the room lights; it's mounted outside and above the door so you can turn down the lights before you turn them on - saves that dazzle at 3 in the morning!

Dave

[RzB]

"NoSpam"

Dave, Thanks for your help - I'm sure I'll come back to this post when I get around to the bathroom. At the moment I'm totally swamped by the kitchen. BTW - I'm ex Hursley too ... Roy