Another Bathroom extractor question

[JMFUK]

Hi All

This is my first post to the forum having read it quite a bit over the last year or so. I have tried to find an answer to my situation in the FAQ and WIKI and past posts but did not find it exactly so decided to post. I hope I am not covering old ground with this.

I have notified building regs and had my first inspection on the electrics/bonding done etc. and all went well so I am all legal and above board at the moment. I am just completing the electrics now prior to my final inspection where they will hopefully certify that it all complies. But have hit a little stumbling block.

My problem is the normal one, I have a timer fan and the manufacturing instructions say I need to wire it through a 3 amp fuse, but this cannot be done in line due to the permenant live and switched live, and only being able to find a DP fused spur. I could redo the wiring and place the fuse before the light and fan but this would be alot of work, also, if my calculations are right I think the light in the bathroom may draw just over 3amps anyway (4x12v 10w G4, and 4 x 230v 35w G10?)

My question, is it acceptable to wire in the L,N,E to the DP Fused spur and place another inline 3 amp fuse on the swL and try and fit it into the fused spur mount box?

If I can't do this I will probably need to do a fair bit of rewiring to fit a DP Switch or similar since there was no fan previously so it has not be wired for.

On another subject, the whole upstair lighting circuit (incl fan and Bath Light) will be protected with a 6 amp RCBO which satifys the 17th Edt regs in any case, however I submitted my plans before the 17th edition came in, so would I be subject to the 17th or the 16th?

I hope this is clear but please post back if more info is required.

Many Thanks

Jody

 

[ban-all-sheds]

if my calculations are right I think the light in the bathroom may draw just over 3amps anyway (4x12v 10w G4, and 4 x 230v 35w G10?)

Don't know how you are doing your calculations, but mine come to 180W, plus transformer losses, so well under 1A.

My question, is it acceptable to wire in the L,N,E to the DP Fused spur and place another inline 3 amp fuse on the swL and try and fit it into the fused spur mount box?

Don't know what you mean by "try and fit it into the fused spur mount box". You could have 2 FCUs next to each other, or, as it seems you're switching the fan via the light switch, if you change the latter for a DP one and use it to separately switch the lives for the lights and the fan, you can supply the fan via a single FCU:

If I can't do this I will probably need to do a fair bit of rewiring to fit a DP Switch or similar since there was no fan previously so it has not be wired for.

Not that much more work...

On another subject, the whole upstair lighting circuit (incl fan and Bath Light) will be protected with a 6 amp RCBO which satifys the 17th Edt regs in any case, however I submitted my plans before the 17th edition came in, so would I be subject to the 17th or the 16th?

Doesn't matter - you were allowed to have the upstairs lights on an RCBO under the 16th.

 

[JMFUK]

Many thanks for you reply. I think I will go the DP Switch route. I know it is not too much work but it does mean crawling round in a really small loft maintaining various stress positions .

My calcs are probably wrong, thanks for correcting me ..... it did sound a bit high!

On the "try and fit it into the fused spur mount box" I meant fit it in behind the FCU face plate if that makes any more sense. i.e the swL would be wired into a separate single in line fuse all within the one FCU enclosure. I have a fan isolator switch inline before the FCU and then from the FCU to the Fan so the isolator would isolate all connections in the FCU.

In thinking about this though if the fuse went the face plate would need to be removed to change it and there is then a danger to whoever is doing it if they do not Isolate the fan. Also it would not be an obvious way of doing things, so it is better to spend the time doing it right.

On the 16th or 17th question I was just curious. I started the work when subject to the 16th and my initial inspection was done back then also. However the final inspection will be done in the near future so am just wondering if I need to go back and ensure that the whole bathroom meets all 17th regs. Actually I think it already does but no harm in checking.