Why do I have an FCU and should I keep it?

[dentarthurdent]

I have a feed from the consumer unit, protected by the downstairs lighting RCB, which used to run a bell transformer. It has a 3A FCU (not switched) between the transformer and CU. I would like to run a light and an extractor off this. Is there any object in keeping the FCU (was it there for a good reason?) and what isolator should I use with the fan?

I'd like to run a timed fan, but I'd like the light to be switchable independantly. This is in a windowed toilet - under the stairs.

I'd be grateful for any advice your combined expertise can provide.

 

[ban-all-sheds]

I have a feed from the consumer unit, protected by the downstairs lighting RCB, which used to run a bell transformer.

The way you say that leaves little doubt that it no longer does run a bell transformer.

(was it there for a good reason?)

It was there to fuse down to the requirements of the bell transformer.

The bell transformer is no longer there.

Is there any object in keeping the FCU

The bell transformer is no longer there.

and what isolator should I use with the fan?

One which will isolate all the conductors to the fan, so if you put it after the switch you'll need a 3-pole one, if you put it before then you'll only need a 2-pole one.

I'd like to run a timed fan, but I'd like the light to be switchable independantly.

You'll need two switches then - one for the light and one for the fan.

This is in a windowed toilet

Does the window open?

 

[ban-all-sheds]

well artur dent, i think the guide says "if all else fails look in the sticky or wiki" (and while arthur was looking at the book some pictures appeared)

and while BAS was typing his post, breezer's post disappeared....

 

[dentarthurdent]

The window can be made to open, though that may constitute another DIY project, since it was secured and boarded up after a football accident. I presume an opening window affects the regs regarding extractor fans?

I am grateful for your reply. Actually, the transformer circuit was lacking an earth, so I shall renew the cable and make a clean start.

 

[ban-all-sheds]

I presume an opening window affects the regs regarding extractor fans?

It means you don't need one.

Even if you never actually open the window.

But then again - if the toilet is already there there's no compulsion to install a fan even if it's required by the Building Regulations.

Of course, you may well want a fan whether you have to have one or not. Don't get a puny 4" jobbie - it won't cope with jobbies.

Even puny 4" ones....

 

[dentarthurdent]

Thank you Ban-all-sheds, most useful. I'll come clean - the toilet itself is actually just a twinkle in my eye at the moment, but I have 12 coming for Christmas, so it needs to be there!

I am interested in getting a fan which makes a difference; I note your comment on choice of unit. Can I still run a higher-rated one from the lighting circuit? I'd imagined mounting it in the top (non-opening section) of the window, through a timber panel. The floor void above has absolutely no space for running a concealed duct.

I was considering simplifying things and just providing a switched two-pole FCU mounted on the CU board in place of the redundant one, to isolate all the toilet electrics. Would this fulfil the regs?

I also have the challenge of making the wall fart-proof, of course.

Any comments welcome.

 

[ban-all-sheds]

Thank you Ban-all-sheds, most useful. I'll come clean - the toilet itself is actually just a twinkle in my eye at the moment, but I have 12 coming for Christmas, so it needs to be there!

You'd better crack on then, as you need Building Regulations approval, and possibly connection approval from your sewerage undertaker.

And for the sake of a fan it's probably not worth arguing the toss with the BCO about the opening window.

I am interested in getting a fan which makes a difference; I note your comment on choice of unit. Can I still run a higher-rated one from the lighting circuit?

You can run any size you'd ever consider getting from the lighting circuit.

I'd imagined mounting it in the top (non-opening section) of the window, through a timber panel.

Seems a shame to reduce the amount of daylight - why not drill through the wall?

I was considering simplifying things and just providing a switched two-pole FCU mounted on the CU board in place of the redundant one, to isolate all the toilet electrics. Would this fulfil the regs?

That would be OK, as long as there'd be enough daylight to work on the fan when necessary.

I also have the challenge of making the wall fart-proof, of course.

Mine needed to be Lamb Jalfrezi-proof this morning....