Bathroom questions.....

[bradhawkins7]

Hi all

I am redoing my downstairs bathroom to include water based underfloor heating. All the cabinets, radiators, fixtures, fittings and tiles to be replaced.

What are the thoughts of an extractor fan in the bathroom? It is a smallish bathroom with an airbrick to the outside and an opening window. Would an extractor fan be overkill or useful to reduce condensation.

Another thing, there is an electrical wire coming out of the wall above the basin unit. It was connected to a light fitting in the cabinets. Would this be 240 Volts? The wire is embedded in the wall and I cant see where it comes from or whether there is a transformer or anything. Perhaps this is controlled by the main light switch to the bathroom found outside the bathroom? Or was it only controlled by the cabinet light switch. So many questions......

There is also an electrical spur from a socket in the bedroom alongside which connects to the towel radiator.

All help greatly appreciated.

 

[Spark123]

Extractor fans are usually a good idea.

You'll have to assume it to be a mains cable poking out the wall until it is proved otherwise - likelyhood is it will be mains.

Are all circuits within the bathroom protected by a 30mA max RCD?
Are all the circuits supplementary bonded to gether and to all metal pipework?

 

[bradhawkins7]

Extractor fans are usually a good idea.

Ok - then I intend to extend the circuit from the lights to the extractor fan. So the fan will come on when the lights are switched on. Any suggestions as to what kind of extractor to get?

You'll have to assume it to be a mains cable poking out the wall until it is proved otherwise - likelyhood is it will be mains.

Should I terminate this within the wall and tile over? How do I do this?

Are all circuits within the bathroom protected by a 30mA max RCD?

I doubt it. How would I check. If they aren't, can I install one myself. What is involved?

Are all the circuits supplementary bonded to gether and to all metal pipework?

I am not sure with regards to the terminology? The pipework is all earthed just outside the bathroom with some green and yellow cables. Are you suggesting that I take the earth cable from the extractor fan and from the towel radiator heating element and join them to a pipe and then make sure all the other pipes are joined to the "earthed" pipe either directly or via an electrical wire "bridge"?

Thanks for the patience......i am new to this.

 

[ban-all-sheds]

So you are re-doing your bathroom, including electrical work, and you don't own a multimeter or know where to isolate the circuits entering the bathroom.

That is a very bad combination.

 

[bradhawkins7]

So you are re-doing your bathroom, including electrical work, and you don't own a multimeter or know where to isolate the circuits entering the bathroom

That is why I am doing the research. Is this forum the correct place to look for help on this type of thing? I also figured that if I replace like for like the situation will be no worse than when I started.

Any help still greatly appreciated.

 

[ban-all-sheds]

Is this forum the correct place to look for help on this type of thing?

Yup.

The Wiki and For Reference topics are very useful.

Another thing, there is an electrical wire coming out of the wall above the basin unit. It was connected to a light fitting in the cabinets. Would this be 240 Volts?

Nobody who isn't there can possibly tell. Buy a multimeter and measure it.

Perhaps this is controlled by the main light switch to the bathroom found outside the bathroom?

Perhaps. Nobody who isn't there can possibly tell. Buy a multimeter and see if the light switch controls it.

Ok - then I intend to extend the circuit from the lights to the extractor fan. So the fan will come on when the lights are switched on. Any suggestions as to what kind of extractor to get?

One with a timed overrun. Look through the Wiki for rules regarding bathroom zones to see whether you need a SELV fan for where you want to put it, or if LV will be OK.

Don't forget to also read the rules regarding Part P.

Should I terminate this within the wall and tile over?

Not unless you disconnect it at the other end - the Wiki has info on rules for concealed cables.

Are all circuits within the bathroom protected by a 30mA max RCD?

I doubt it. How would I check.

Look at your CU.

If they aren't, can I install one myself. What is involved?

You could change your CU, or add an external RCD for the circuits concerned, or change MCBs to RCBOs, or rearrange/modify your CU. Nobody can tell what would be best without being there.

Don't forget all of that is also notifiable.

Are all the circuits supplementary bonded to gether and to all metal pipework?

I am not sure with regards to the terminology?

See the Wiki.

The pipework is all earthed just outside the bathroom with some green and yellow cables.

That's bonding, not earthing. See the Wiki.

Are you suggesting that I take the earth cable from the extractor fan and from the towel radiator heating element and join them to a pipe and then make sure all the other pipes are joined to the "earthed" pipe either directly or via an electrical wire "bridge"?

See the Wiki.

I also figured that if I replace like for like the situation will be no worse than when I started.

But if it didn't comply with BS 7671 before you started then you may not be able to leave it non-compliant, assuming that BS 7671 is to be your route to compliance with P1.

Thanks for the patience......i am new to this.

• //www.diynot.com/forums/viewtopic.php?p=75416#75416
• http://www.tlc-direct.co.uk/Book/1.1.htm (out of date, but the basics don't change)
• http://www.kevinboone.com/electricity.html
• http://www.kevinboone.com/domesticinstallations.html
• http://www.kevinboone.com/cableselection_web.html[/list]

 

[stem]

Electrical equipment in bathrooms must be suitable for the Zone in which it is located.

If a fan is installed in Zone 1 above the bath for example, it will normally need to be a 12v fan supplied from a transformer mounted elsewhere (SELV)

Look on the websites for Vent Axia & Xpelair etc. for suitable fans

Also see link for details of bathroom zones

http://www.fantronix.com/acatalog/bathroom_Zones_Explained.html