Underfloor Heat Mat Earth Grid

[sparkie_Al]

Hi,
I have a customer who has purchased a underfloor heat mat for his bathroom, to fit under his carpet. When fitting this thing I told him it required an earth, as it was not within the cable feeds to the elements. I put a 1.5mm Earth cable down to behind a pedastal basin, so that they could plaster and finish the walls, however the company that supplied the heat mat say that their mats are double insulated and do not require an earth!!(in the UK they definately DO) Every wholesalers that I have tried say that no such earth grid mat is available for underfloor heating, so I am hoping someone on this forum has indeed come across a solution to this, as so far I will not connect until it complies.

 

[Philpot]

The problem with introducing an earth to a DI device of any sort it the you will possibly introduce an additional risk. After all what are you going to attach it to? I have heard of people putting an earth to DI down lighters and causing more trouble than they cure.

The bit I am not clear on is ....is the mat designed to go under a carpet. I cant't say I have ever installed one underneath a carpet as they would be in danger from high heeled shoes to name but one.

 

[Philpot]

Hi again Sparkie I did say that I had not fitted one but it seems that they are about. Underfloor Heating | Underfloor Heating Systems


It seems that the manufactures instructions are the the most important consideration and the necessary EC etc certificates of compliance. It just seems that it a problem waiting to happen when they have been installed for about 10 yrs....maybe I'm being a bit cautious?

Who make the one you are being asked to install?

 

[sparkie_Al]

The problem with introducing an earth to a DI device of any sort it the you will possibly introduce an additional risk. After all what are you going to attach it to? I have heard of people putting an earth to DI down lighters and causing more trouble than they cure.

The bit I am not clear on is ....is the mat designed to go under a carpet. I cant't say I have ever installed one underneath a carpet as they would be in danger from high heeled shoes to name but one.

Hi
Thanks for reply, however I do not believe that there is such a thing as DI underfloor heating mat that could comply with the regs in the UK, I telephoned the company direct and they had to agree that it did not comply. The mat is designed for under carpet on wooden floors too!

 

[sparkie_Al]

The underfloor heating store! London based I think. I feel that it could never comply with any room, let alone a bathroom. I have also seen people advising to earth the RCD protecting the Mat only...which I am afraid I disagree with.
I also think the IEE regs would be against the manufacturers instructions should someone be killed.

 

[Sparkii]

I've fitted a few heating mats under in kitchens/bathrooms that havent had an earth included, always been able to source a seperate earthing grid pretty easily, jus sits on top of the heating mat. Never fitted one under a carpet though...

Google "allbrite grounding mat"

 

[Philpot]

It is a case of the availability of new innovations before the regs have caught up. We are just left to do the best we can but then that leaves us exposed if things go wrong. This is not very helpful as it just states the obvious but there may be no definitive answer at present. Have you talked to the IET, they have a help line that may be able to give some guidance.
They just don't sound like a good idea to me. 230v heating cable under a carpet ?????

Please let us know what you decide to do.

 

[sparkie_Al]

I've fitted a few heating mats under in kitchens/bathrooms that havent had an earth included, always been able to source a seperate earthing grid pretty easily, jus sits on top of the heating mat. Never fitted one under a carpet though...

Google "allbrite grounding mat"

Mint! I will be checking ASAP.

I agree with Phillpot though heating mat bathroom and carpet.....no good
I will let you know what transpires.
AR

 

[sparkie_Al]

AllBrite Grounding mat ordered, will let you know what the result is.

Thanks for replies.....

 

[trev]

however the company that supplied the heat mat say that their mats are double insulated and do not require an earth!!(in the UK they definately DO)

Can you quote a reg on that please mate. Even if you can, is it not the case that the manufacturer's requirements rule

 

[sparkie_Al]

however the company that supplied the heat mat say that their mats are double insulated and do not require an earth!!(in the UK they definately DO)

Can you quote a reg on that please mate. Even if you can, is it not the case that the manufacturer's requirements rule

It will be in the Special locations bit, 750 whatever. No The manufacturer have not said their mat is DI but the Supplier did, even so, if there was a death resulting from this or a similar installation, it would be the regs that were thrown at you. I bet you could not just say...I followed the suppliers instructions.

I maybe wrong, but DI underfloor heating Mat...Nah dont buy that one sorry.

I am pretty sure that The regs want an RCD controlled heat-mat, so without an earth potential apart from say supplimentary bonding, if the customer was being fried, you have to hope she/he touches a tap, to operate the ADS. could not be happy with that.

 

[trev]

Al I've fitted a load that have had the DI symbol on the box and in the instructions. Be very careful adding earths to things which may not need them, you're inviting problems.
I've never seen one suitable for fitting under a carpet mind, but I'm always open to new experiences