Bathroom extractor fan

[davidstewart]

Dear all,

I hope you can help.

I have an S.E.L.V. (low voltage) fan (this) installed in the bathroom. The fan unit itself is directly over the shower which according to the instructions is fine.

The transformer is right next to the fan, though. This is not fine as it is in the splash area by the bath. It has been disconnected and made safe by an electrician.

The electrician wants to move the transformer. out of the splash area of the bath. I understand why and am happy with this. But he claims that it needs earthing with a massive 10mm or 15mm (can't remember) earth which has to be connected to the switchboard 2 floors down. He also wants to install an RCD. There is nothing about this in the instructions for the fan, though.

His reasoning was that this is part of the 17th edition electrical regs: whenever you have any electrical devices other than lighting in the bathroom you need a massive fat earth cable and an RCD.

I think he might be being over-cautious--obviously what he proposes will cost lots of money. How much of this is actually necessary?

David

 

[Sparky Ninja]

He is wrong, I think he is confused.

The room is considered a special location in the wiring regulations and certain criteria have to be achieved.
It is likely that if he has to install more cabling in this area then it will need RCD introduction.

Is there access to above? Or is it a concrete ceiling affair?

Regarding the earthing, supplementary bonding may be required to create an equipotential zone, if this is the case it would be amongst the metal pipework withing the room and not at the transformer as the already existing earths in the cable (assuming there is one) can be used.

 

[m4tty]

You sure he's not upgrading the water bonding to 10mm not running it to the bathroom but to the water meter? Sounds more like it

 

[davidstewart]

widdler:

yes--I think I have negotiated access above from the upstairs neighbours so he/they should be able to rewire and reposition the transformer with no problem. There are other complications--fibreglass near the lights making the wiring melt--that they have to sort out anyway.

Bonding--they also do want to do this. Initially they wanted to take a 10mm cable from the combi-boiler next to the bathroom to the switchboard through the 2 floors of the house but I managed to convince him to simply bond across the pipes at the boiler and then bond and earth the pipes in the kitchen as they will ultimately be connected. So now he (only) wants to take a 10mm cable from the kitchen pipes to the switchboard which is on the same floor as the switchboard is. He also wants to RCD the switchboard.

Where can I find out the criteria for needing an RCD?

m4tty: the water meter is in front of the property (patio) next to the electricity meter. I would be very surprised if that has not been properly bonded as it's easily accessible to the water company.

He DEFINITELY initially wanted to bond the pipes at the boiler on 1st floor then run a cable from there to the kitchen pipes (basement), bond again and then continue running the earth to the switchboard.

Now he is saying that he can avoid running the massive cable IF I change the extractor fan to a non Low Voltage one and move it so it's out of the splash area.

Thanks both for help!

 

[Des 56]

This thread seems to portray 2 things to me
Firstly the person posing the questions is unclear on requirenments of Bs7671 and what is entailed with earthing and bonding and his choices
second ,the electrician may have been responsible for this, by either being wrong or his recomendations were mis understood
You need David to explain first
What work was the electrician engaged to do
Why were you not informed of adequacy of earthing bonding and rcd protection at the tender stage

 

[davidstewart]

When you say the 'tender' stage, do you mean the survey when I bought the house?

Was 4 years ago so maybe it did not need rcd protection at that stage?

There is 'bonding' in the kitchen but the electrician says it doesn't go anywhere. So there is a green wire but there is nothing connected to earth. So possibly the surveyor had a brief look, saw the green wire and thought it was all bonded AND earthed?

David

 

[Des 56]

Badly worded on my part sorry david
What was the electricians role ?
Was he there to do work on your behalf ?
Was it a periodic inspection, engaged by yourself or others ?
Earthing and bonding are seperate issues
The electricians duty and the work involved, can be better explained, if it is known what his function was in the first place, and the type of work he was there to do. and then the requirements and procedures can be made clearer to you

 

[davidstewart]

Badly worded on my part sorry david
What was the electricians role ?
Was he there to do work on your behalf ?
Was it a periodic inspection, engaged by yourself or others ?
Earthing and bonding are seperate issues
The electricians duty and the work involved, can be better explained, if it is known what his function was in the first place, and the type of work he was there to do. and then the requirements and procedures can be made clearer to you

One electrician came to sort out the extractor fan on my behalf. The bathroom installation was done by some Polish builders who, it subsequently turns out, may not have known exactly what they were doing. Anyway, the fan was not working.

He was looking for the permanent live; there was a switched live, left by the Poles, but it's a timer fan so it needs both. Electrician unscrewed some spotlight fittings to try to find it. But he discovered there was fibreglass in the ceiling above which was insulating the lights and burning the wire around when turned on.

This guy called his mentor, who is NICEIC registered, to ask for advice. Mentor comes round and agrees that the lighting needs condemning until the fibreglass is removed.

The mentor then goes around looking at the rest of the installation and property more generally. No bonding in the bathroom or kitchen, he says, though can be fixed by bonding across the five pipes coming from the boiler. This seems reasonable to me. What did not seem reasonable was the idea that a fat earth cable needed taking through the property from the boiler to the switchboard.

Again there's a green wire hanging about in the pipes underneath the sink in the kitchen, but I don't know what it's connected to. Electrician says that they are connected to nothing useful.

So the plan was to bond all the pipes AND earth them. Again, I can see the point of this; but if all one needs is an 'equipotential zone' then this is, I imagine, bonding without earthing? So again, do not see why fat earth cable etc.

I explain my reasoning which seems to go down okay, resulting in a reduced quote, but then he says that the earth is needed for the extractor fan so if I want to use this fan then I may as well have the earth cable attached to the bonding at the pipes at the boiler anyway. BUT if a DIFFERENT (non low-voltage) fan is used it needs to be relocated as it should not be in the splash area.

However, I know that the fan I have IS designed to go in the splash area, while the low voltage transformer should be moved to be outside the splash area.

If there is no bonding, it is, I imagine, a pretty quick job to sort it out. Is it typical to EARTH pipes in a property or not? Do you just need to earth one of them (like at the meter) on the basis that the rest of them will be earthed in turn as a result of the bonding that you have done?

David

 

[nickblake]

Under 16th edition earth supplimentary bonding is required ,but we are no up to 17th edition , bond to water and other service is required this has to be installed within 600mm of the incomming services , if you have no RCD protection , then it would be advisable , if you have your main bond to water gas oil etc 10 mm and you have a new distribuition board so that you meet the requirements of the regs then you can eliminate the need for supplimentary bonding , some fans also require additinal fusing as well as isolation switches for maintainance ,the supplimentary bonding can be a minimum of 4 mm thats if required