Illuminated Bathroom mirror - not so simple???

[rhbmcse]

Hi,
I'm a competent DIYer with an illuminated bathroom mirror to fit tomorrow. However, I have a query...

It look like the ceiling rose for the bathroom light that I was going to use to connect the illuminated mirror to has already been used for the ceiling fan in the bathroom. Both the fan and the light are on their own respective switches.

I havent been into the loft space yet to confirm this but it looks like it - in the ceiling rose I have 3 x permanent lives, one switched live, 3 neutrals and an earth, so somethings going off there...and I'm assuming the fan has been connected in to the terminals.

Given that I have to add an illluminated mirror into the equation too, what would be the best way to do this safely, and yes I am well aware of the regulations concerning this, along with zones etc...

Incidentally, the mirror has its own built in switch and transformer, so all that would be needed is a straightforward live, neutral end earth.

Thanks for any advice.

Rob.

 

[ban-all-sheds]

I'm a competent DIYer

in the ceiling rose I have 3 x permanent lives, one switched live, 3 neutrals and an earth, so somethings going off there

That's short to the tune of 1 neutral and 3 earths....

...and I'm assuming the fan has been connected in to the terminals.

Don't do the work on the basis of assumptions - check it out.

Given that I have to add an illluminated mirror into the equation too, what would be the best way to do this safely,

Whatever else is going on at the rose you seem to have the permanent L/N/E that you need, but you'll probably struggle to get another cable in there.

I'd suggest installing a JB to take the existing and new cables

and then run cables from there to the ceiling rose, the fan, the mirror etc.

What do you plan to do about RCD protection for the mirror cable?

 

[rhbmcse]

Thanks for the speedy response - glad somebody else has nothing better to do an a fri night!!!

I absolutely will be getting into the loft space tomorrow before proceeding to find out exactly what is going on up there.

I have however just re-checked my facts and yes - the earth's will be tucked away in the roof space you're absolutely right. I definitely only have 3 x neutrals and 3 permanent lives connected into the rose.

I expected typically

1 x perm live from previous rose
1 x perm live to next rose
1 x perm live to switch

So that's the perm lives catered for

1 x Neutral from previous rose
1 x neutral to next rose

Instead of this I have 3 x neutrals which has thrown me a tad (when I say 3 this excludes the one connected to the fittiing itself - I'm referring to the thicker twin and earth style cable)

And of course the earths which Im sure will be in the loft space (they have to be unless my 5 year old house is very dangerous)...

I hadnt given consideration to a separate RCD for this device but it sounds like youre going to tell me that I should do...

Again, glad to take your advice and guidance on this.

Rob.

 

[rebuke]

Any electrical equipment in a bathroom should be RCD protected now, so if your lighting circuit isn't (quite likely if you haven't had a new CU recently), you'll need to add RCD protection somewhere.

Easiest way if your CU will support it would be to swap the current MCB for an RCBO, if this isn't practical, then you could put a small RCD unit just outside the bathroom, fed from the lighting circuit, and then feed the ceiling rose / junction box or whatever from the output side of the RCD. I'm thinking of something such as this: http://www.tlc-direct.co.uk/Products/CM4904.html

Obviously, swapping MCB for an RCBO is notifiable under Part P (as is adding this bathroom mirror, but since you state you are aware of the regulations then I assume you've already notified your LABC etc...)

 

[rhbmcse]

The house absolutely does have RCD protection (its only 5 years old) and thinking about it, it does cover the lighting circuit as a few times now when a bulb has blown, it has tripped the RCD out.

The only thing really perplexing me is why so many neutrals.

I guess I'll find out tomorrow but any suggestions so that I can actually have a decent nights sleep without thinking about it all night!?? (Yes I have that affliction).

 

[rebuke]

Obvious question, but are you sure it's an RCD that trips, not just an MCB (easiest way to tell is RCDs normally have a test button)?

Five years ago would have been the 16th edition of the regs, which didn't require RCD protection on cables buried less than 50mm in a wall, or lighting in a bathroom AFAIK (which are the reasons most lighting circuits are now RCD protected), so it's fairly unusual to find lighting circuits on an RCD unless the property has been recently rewired (or e.g. the entire CU is protected by one RCD because it's a TT system or whatever).

If you're not sure, then if you upload a pic of the CU, I'm sure plenty of people on here will be able to tell you. Obviously worth getting it right otherwise when the LABC inspect, if it's not RCD protected they will just make you sort it out...

 

[rebuke]

It does sound odd the number of wires you have, but at a complete guess, you might have:

Lives:
Supply in from previous fitting
To switch
Supply out to next fitting

Switched live back from switch

Neutrals:
Supply in from previous fitting
Supply out to next fitting
Neutral return from fan (e.g. if it takes its live from the perm. live going to the switch, it would still need a neutral from somewhere)...

 

[rhbmcse]

Yep, definitely RCD protected - 80A RCD with 30MA stamped on it. I'm absolutely positive that the RCD has tripped out on previous occasions of bulb blowing - I used to be area manager at a well known hire shop so I know about RCD protection, however, Im no electrician...

I had been thinking pretty much the same as you on the neutral front.

As the switch is a dual switch, the (common) permanent live comes into one common terminal in the back of the switch and has a short piece in linking it to the common for the other switch.

Therefore the fan would be taking it's switched live from there and presumably the neutral from the fan...but...better safe than sorry, I'll check it out tomorrow.

Thanks for all your help everyone.

Invaluable as ever.

Rob.