Wiring bathroom fan/light combo

[sergeantash]

Thanks Holmslaw. One last question, I am also fitting a mirror with demister pad and built in pullcord on/off function - could this come from the 3amp FCU or once again a separate one?

 

[holmslaw]

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[sergeantash]

Never seen a demister, but assuming its 200 or 300 watts, treat it the same as the shaver point. What rating is it? in watts

Approximately 8 watts for the demister and builtin lights for the mirror.

Also for this entire circuit spurred from the light loop, is 1mm or 1.5mm cable satisfactory?

 

[bongos]

It must be more than 8w. Have another look...

1.5mm² should cover it. Make sure it is no smaller than the existing lighting cable though.

 

[sergeantash]

It must be more than 8w. Have another look...

Lol I've confirmed with the manufacturer and the demister pad is 4w (very low ampage heatmat), and the builtin LED's (60 of them) total 0.1w each giving a total 6w, so therefore 10w for the complete unit

I'd prefer not to have another FCU so could I pair this from the fan's FCU?

1.5mm² should cover it. Make sure it is no smaller than the existing lighting cable though.

Cool, this is what I had hoped as I've already started to lay down the basics.

Thanks for your help!

 

[sergeantash]

Quick question, on my CU, the light circuit upstairs is protected by a 5amp circuit breaker (dedicated mini trip switch), am I right to assume that in this instance you would classify that circuit as RCD protected and hence on FCU's would be required for any bathroom related items?

The reason that I ask is that in the bathroom, I am replacing the pendant lamp with 12v downlighter spots (with inclusive transformer) and the instructions state the following "If being fitted in a bathroom, a 30mA RCD must be used", so is my circuit already protected at the CU due to the circuit's dedicated 5amp circuit breaker?

 

[holmslaw]

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[sergeantash]

A circuit breaker is not the same as an rcd.

And an rcbo combines the functions of a circuit breaker and an rcd.

Either, change the 5A breaker for a 5A 30mA rcbo,

Or, fit a 5A 30mA rcd in an enclosure beside the cu, and wire from the circuit breaker through the rcd and then to the bathroom.

Rcd's and rcbo's have to be tested to prove correct operation so you need to contact a spark with the correct test equipment.

Thanks for your patience here, looks like I'm making a lot of work for myself, in summary here's the electrical changes to the bathroom...

Presently there is just a single ceiling rose which I am removing to replace with the following:

- Mirror with demister and LEDs (8w total) - loose wires
- 10 x 12v Mini LED's in bath panel (0.1w total) - transformer fused plug
- 5 x 12v downlighters (100w total) - loose wires
- Shower Fan/Light Combo unit (50w total) - loose wires

I intend to power all of the above via the lighting circuit above the bathroom (within the loftspace) - Sorry to be a pain but could you help me to plan what needs protecting via what means so as to make this circuit efficient without needing multiple RCD and FCU units?

The only two elements that won't be controlled via the bathroom pullcord will be the 10 x LEDs and the Mirror so I assume they could be connected via a single FCU?

Finally, I'm a bit confused as to the FCU and RCD bit - on what occasion do you need one, the other or both?

Really appreciate the help!

 

[holmslaw]

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[sergeantash]

I think you should contact a part p registered spark, this is less than a days work.

I'm concerned that you have'nt got your head round you're requirements.
eg. you now advise you have "10 x 12v Mini LED's in bath panel (0.1w total) - transformer fused plug".

I do appreciate that but I am on a budget and want to get my head around the protection elements that I have to implement to look after it all, I genuinely do want to learn.

Sorry I didn't mean 'fused' transformer - but I wanted to reflect that the LED's are equiped with a transformer plug, not bare wires - i.e. I'll need a socket into which to plug it.

I just found this quote from an electrical information site compliant with 17th ed...

If the only work you are carrying out is the replacement of the light fitting, I would recommend that you provide RCD protection for the lighting circuit. You would not, in my opinion, be required to provide RCD protection for other circuits within the bathroom, although this could be commented on in any certification provided.

Would it be acceptable to protect the entry of the bathroom lighting circuit with an RCD so that all electrical elements are RCD protected within the bathroom loop-in, then use individual FCUs per additional element?

 

[sergeantash]

As the topic has changed a bit, I've started a new thread and posted a diagram of what I intend to achieve:

//www.diynot.com/forums/viewtopic.php?p=1603547

Thanks again for the help from all of those that responded.