shower extractor fan

[Big_Spark]

Thanks a lot for the lively discussion, guys (& gals?) I find the points raised very helpful particularly the issues on fusing and the discussion on a potentially dangerous bridge.
For safety sake I think I'll install an untimed fan with an in-line lowered fuse to protect the fan.

Good stuff!!

Bry, if installed correctly, as I describe above, there is no danger installing a timed fan. Plugs has read the post incorrectly and introduced a dead argument.

 

[Bry]

Cheers ban-all-sheds.

I see you're based in France where my brother has a house.
Are you familiar with French wiring as well as it seems very different.

(Thinking of any problems you may be able to help with in the future)

 

[BR]

Ban, along which others using this forum appears to be touring the world present!

FWL, I think i can see were plug is coming from, as it is labelled "bad practice" in our RECI handbooks and is not permitted in a commercial/industrial installation. (just a piece of info, not casting any aspersions as to the situation in the UK!)

Suppose the permanent live for the overrun was to become shorted to the switched live, then the isolator would be bridged with a section of 1.5mmsq cable. (Personally I see no problem with what you suggest though. An example of yet more nonsense from RECI)

 

[Big_Spark]

FWL, I think i can see were plug is coming from, as it is labelled "bad practice" in our RECI handbooks and is not permitted in a commercial/industrial installation. (just a piece of info, not casting any aspersions as to the situation in the UK!)

Suppose the permanent live for the overrun was to become shorted to the switched live, then the isolator would be bridged with a section of 1.5mmsq cable. (Personally I see no problem with what you suggest though. An example of yet more nonsense from RECI)

Bryan, what on earth are you talking about, there is nothing wrong with the circuit I have laid out, it is normal and the way timed fans are installed, regardless of the circuit they are fed from, that is the whole point of triple pole switches.

Plugs post makes no sense what-so-ever as he has mis-read the original post and mis-understood how the circuit is connected.

If your RECI have a problem with that circuit, then with all respect..That's Irish!

 

[BR]

i do agree with you, as i already said. I was just supplying info as to the situation in ireland which yes (i agree again) is pretty of the wall.

But, you do see where this is coming from, suppose the 1.5sq from the shower isolator to the FCU became damaged and the permanent live and the switched live became shorted out, there would be a live path to the shower via a piece of 1.5sq cable.

Again, RECI rules on this are nonsense in my opinion. I was just trying to clarify what plug might be thinking.

 

[Big_Spark]

But, you do see where this is coming from, suppose the 1.5sq from the shower isolator to the FCU became damaged and the permanent live and the switched live became shorted out, there would be a live path to the shower via a piece of 1.5sq cable.

That happening is like Adolf Hitler climbing out of his grave and declaring undieing love for Israel!

IF this that and the other happened to any circuit it could be dangerous...that is the whole point of earths and correct circuit protection.

And also, your example is electrically impossible Brian, re-read what you posted mate, then look at the circuit diagram again. What you propose CANNOT occur.

 

[BR]

LISTEN!
I agree with you.
You are correct.
I believe that how you suggest is a suitable way of connecting this fan!

I have meerly being trying to show where somebody might be coming from and a reg here which agrees. No matter how much shi*te the entire thing might be.

 

[ban-all-sheds]

I see you're based in France where my brother has a house.
Are you familiar with French wiring as well as it seems very different.

Err - no and no, I'm afraid.

I was there this week, and whimsically made a temporary change to my profile. Flew back to Blighty today.

 

[securespark]

I was just about to say Allez F****.........!

Bienvenue, mon ami!

 

[phhut]

Searched here to find the answer to whether to wire my selv shower fan to the light circuit or to the electric shower - either has advantages and disadvantages. Found this discussion which almost answers me.

However the wiring diagram supplied by your good self FWL does NOT answer the original proposition if the timer option is required...

The "Shower Unit" drawn is presumably the actual shower and you have excluded the shower switch (wall or ceiling) which will be off to the left somewhere.

When the shower is switched on, power will flow to the switched fused spur, and on into the fan, with the timer bridge allowing that to happen. BUT, as soon as you switch the electric shower off then power is disconnected from the FSU and hence the timer and hence the fan. So the fan will not continue to run for the desired overrun.

I think this is where Plug was questioning the possible bridging - to get the fan to continue running after the shower is switched off, the live must come from before the shower switch (or 'upstream' as I think you said at the start FWL, but somehow was later overlooked).

To get around the bridging problem, ALL the circuit should come from before the shower switch, but then the shower switch will not turn on the fan!

 

[ban-all-sheds]

I don't believe that there is a bridging problem.

There is a fusing "problem" - both the live feed and the switched live come from the shower circuit, which is going to have a 40-50A protective device. So you need 2 3A fuses - probably the neatest way to do that would be to use a 2-module grid plate mounted in a dual box next to the fan isolation switch. If somehow the fan went haywire and did bridge the sower switch, and the shower had been left on, one or both of those 3A fuses would blow PDQ.

There are connection "problems". Ideally you should use the same size cable as the shower circuit to feed those two fuses, and the fuse modules are not designed to take 10mm² conductors. I believe that a short, well protected length of smaller cable is allowable, but connection problem #2 is that you'll struggle to get multiple conductors into the shower switch terminals, so you'll need a junction box.

There is a Plan B, which still has connection issues to resolve, but solves the fusing one. Use a contactor energised by the switched live to the shower to switch the lighting circuit for the fan.