Diagram review for Bathroom Re-Install

[sergeantash]

Hi all,

Thanks to those that have assisted so far, the old thread was a little cluttered and the topic has changed a little so I thought it best to start clean.

I have created a diagram to show what I intend to do/have done, please could someone take a look and let me know whether this is safe and the best way to achieve the end goal.

Untitled

• sergeantash
• 6 May 2010
• 3

This circuit will spur from the upstairs light circuit within the loft replacing the bathroom's existing single pendant loop-in, the circuit is connected at the CU via a 5amp trip-switch.

Many thanks in advance for your help

 

[1john]

why are you using FCU's ??

 

[sergeantash]

why are you using FCU's ??

It was suggested in a previous thread by Holmslaw and Bongo that a 3amp FCU should be used for the fan circuit

If the circuit already has RCD protection then you could just use a standard FCU fitted with a 3A fuse.

Are they not necessary in your opinion? Thanks for your help.

 

[sergeantash]

I have just noticed that I missed the isolation switch for the fan, ill add this later

 

[electronicsuk]

Although there are many finer points to electrical installations in bathrooms beyond the functional layout of the circuit, what you propose should work. However, the mirror de-mister and LED lights will be on all the time, unless you plan on using a switched FCU to control them. If that is indeed the plan, you'll need to consider where you locate it, which will most likely be outside the room.

You also haven't accounted for any timer run-on for the fan, although this would only require an extra core from the JB to run a permanent live.

You also don't need to use 30A junction boxes on a lighting circuit that is presumably protected at 6 or 10A. I assume there is no RCD protection at your consumer unit?

Finally, you may not need an FCU for the fan - you'll need to check the instructions, as some manufacturers stipulate one be fitted, others don't. In any case, an RCD FCU fused at 3A and protecting the fan, demister, LED lights and downlights should be more than adequate on its own.

 

[333rocky333]

You also don't need to use 30A junction boxes on a lighting circuit that is presumably protected at 6 or 10A.

Proberly unlikely to get a 30 amp with 4 terminals anyway.

 

[sergeantash]

Thanks for all of the feedback, just to clarify some points from questions asked:

- Yep happy that the mirror and LED's remain on permanently as during the day someone might not switch on the bathroom light, in which case I want the mirror lights to still illuminate.

- I have already bought some circular 4 pole 20amp and 30amp junction boxes from B&Q, I assume they're fine to use anyway besides their generous amp allowance?

- The fan that I have chosen doesn't have a timer circuit, I'm a bit annoyed as I didn't notice that there were two variants at the time but I'm stuck with the non-timer version now so at least won't need the permanent live to it. Guess I can always leave the light on

- Regarding the FCU for the fan, the instructions say that it should be protected with a 3amp fuse, however UltimateHandyman (http://www.ultimatehandyman.co.uk/diy/electrics/extractor_fan/shower_extractor_fan_fitting.htm) doesn't state that one is required - for safety shall I leave that inline with the circuit?

- An electrician friend mentioned earlier today that all the elements (fan, leds, mirror and bathroom lights) need to be protected by their own specific FCU with appropriately amped fuse but with an RCD inplace however protecting the entire spur (as per my diagram) am I safe to stick an FCU only on the fan unit?

I won't get chance to amend the diagram until tomorrow but will at that point add the Isolation switch.

Thank you very much for your help guys!

 

[electronicsuk]

- I have already bought some circular 4 pole 20amp and 30amp junction boxes from B&Q, I assume they're fine to use anyway besides their generous amp allowance?

If they are capable of securely holding the conductors then there is no problem.

- Regarding the FCU for the fan, the instructions say that it should be protected with a 3amp fuse, however UltimateHandyman (http://www.ultimatehandyman.co.uk/diy/electrics/extractor_fan/shower_extractor_fan_fitting.htm) doesn't state that one is required - for safety shall I leave that inline with the circuit?

If the instructions specify a 3A FCU then really you should fit one. It's not at all uncommon for many people, electricians included, not to bother, but that doesn't make it right.

- An electrician friend mentioned earlier today that all the elements (fan, leds, mirror and bathroom lights) need to be protected by their own specific FCU with appropriately amped fuse but with an RCD inplace however protecting the entire spur (as per my diagram) am I safe to stick an FCU only on the fan unit?

I would say that at a minimum the fan and mirror de-mister manufacturers will specify an appropriately fused FCU be fitted. I'd protect everything bar the main room lighting.

There is no need for an individual FCU for each item to be protected, as the entire load is less than 3A anyway, so apart from more points of isolation there is little benefit.

New circuits in the bathroom must be RCD protected, but there is no point in a second RCD if you have a modern consumer unit fitted within the past few years that includes an RCD for the lighting circuit.

 

[sergeantash]

Whooops, duplicate post...

 

[sergeantash]

If they are capable of securely holding the conductors then there is no problem.

Yeah they've got a good secure hold so will be ok, I do always give them a tug before finishing the job to ensure that they're safe and secure.

If the instructions specify a 3A FCU then really you should fit one. It's not at all uncommon for many people, electricians included, not to bother, but that doesn't make it right.

Very true, I guess I'm a bit paranoid about getting third parties in to do jobs on my house because of corner cutting - there are some very good contractors out there, also some very bad so at least by learning about the best way to complete a job, I can ensure that it is done properly. I'll put a 3amp FCU inline as you suggest, good plan.

I would say that at a minimum the fan and mirror de-mister manufacturers will specify an appropriately fused FCU be fitted. I'd protect everything bar the main room lighting.

Cool, so separate FCU for the fan, then a separate FCU for the mirror and LEDs leaving the main bathroom downlighters without an FCU? For the sake of safety and ease of layout, can I run the downlighters through the fan's FCU anyway?

New circuits in the bathroom must be RCD protected, but there is no point in a second RCD if you have a modern consumer unit fitted within the past few years that includes an RCD for the lighting circuit.

I did check my fusebox and it doesn't appear that the upstairs lighting circuit is an RCD tripswitch but I am unsure how to identify the difference - I'll take a photo and post it tomorrow.

The CU looks about 8/9 years old to me, fitting during the house's last rewire before my moving in - all wiring is pre-harmonised colours if that gives any indication.

Thanks again for your assistance!

 

[sergeantash]

Right, here's an updated diagram - I have added the Isolator and although the FCU isn't apparently required for the main bathroom lighting, I was wondering whether it was acceptable to run it through the FCU anyway?

I haven't had chance to check my CU yet but will do tonight, if there isn't an RCD unit MCCB fitted for the upstairs lighting circuit, is it a case of tripping the master switch off and replacing that circuit's fuse unit?

Untitled

• sergeantash
• 7 May 2010
• 1

Looking forward to your feedback!

 

[GaryMo]

- Yep happy that the mirror and LED's remain on permanently as during the day someone might not switch on the bathroom light, in which case I want the mirror lights to still illuminate.

Most LED demister mirrors have a non-touch movement sensor built in so you just wave your hand in front it it to turn it on. It shouldn't be permanantly on.

 

[FDJ]

- Yep happy that the mirror and LED's remain on permanently as during the day someone might not switch on the bathroom light, in which case I want the mirror lights to still illuminate.

Pointless waste of energy
You have money to burn?

 

[sergeantash]

- Yep happy that the mirror and LED's remain on permanently as during the day someone might not switch on the bathroom light, in which case I want the mirror lights to still illuminate.

Pointless waste of energy
You have money to burn?

Sorry guys you've taken me too literally, I mean always on as in provided with a permanent power supply - the switching is built into the device as GaryMo says, the mirror has a built in sensor and the LED's are wireless on/off.

Is everything else compliant and acceptable/safe?

 

[bongos]

It was suggested in a previous thread by Holmslaw and Bongo that a 3amp FCU should be used for the fan circuit

No - I suggested either a RCD FCU with a 3A fuse or if you already had RCD protection I suggested a FCU with a 3A fuse.

These were to provide local isolation for the fan. I didn't mention the lights!