Laminated Foil Underfloor Heating

[shazbutz]

Reading the installation instructions it states that a resistance test and an insulation resistance test have to be completed. No problem with the resistance test across the line and neutral through the foils that produces a figure well within the calculated tolerances for the area of film laid down. How is the insulation test carried out as there is no earth and the line and neutral are effectively the elements within the foils? I just know there is a simple solution..........

 

[telectrix]

is the foil the earth?

 

[shazbutz]

That's the simple solution I reached but the instructions state "test after the flooring is laid" which is tad disconcerting as the heating foils has disappeared under said floor!

 

[Darkwood]

Follow the manufacturers instructions if they are not available on site then download them or contact tech this way you can give a good judgement as to whether its been installed correctly .. their a hundreds of systems out there be it variants of the same brand or indeed different brands altogether so we can't give an informed answer without knowing which one you have.

Sorry you answered partly as i posted... contact the manufacturer then and ask them if the foil is the earth you can't connect it up without ensuring the foil has a good earth to it and as its now buried i think this is possibly going to be an expensive issue to correct. Ill reiterate though the instructions should explain if the foil is the earth.

 

[shazbutz]

Apologies, I did not complete my "that's the simple solution....". I was going on to say that it couldn't be the earth as the laminated foil (with line and neutral connections only) is laid on to a 6mm thick sheet of foam insulation and is therefore does not have a connection with earth. I take the point about contacting the suppliers tech team and will do so. But I'm left wondering if the insulation test requirement is a generic statement that is more appropriate to the wire based systems that the same organisation also sell.

 

[Darkwood]

Id be very surprised if the set up has no earth consider a fault to the floor that may be wet anyone turning the tap on in their bare feet (no sarky comments about why someone has a tap on their foot pls ).

It may be the case its double insulated but again check with the manufacturer is the best solution here if you don't have the info at hand.

 

[jackhammerJIM]

all electric underfloor heating systems i have connected up have a 2 core cable with braided earth .

has the braiding been cut off ?

 

[shazbutz]

No, it's single core double insulated cable. One for line and the other for neutral.

 

[specs]

is the foil the earth?

probably is, never seen one without an earth, 'yet'. OP, make an model no would be helpful.

 

[shazbutz]

It's a Swedish outfit called EBECO and despite reading their installation instructions over and over again the only reference to anything linked to an earth is the requirement for the "installation to be protected by a 30mA earth fault relay. The only occasion the word earth is used. What I'm now wondering is if in Nordic world a 6mm insulation sheet under and a 20micron film over is classed as double insulation!

 

[telectrix]

753.411.3.2 applies.

 

[specs]

"installation to be protected by a 30mA earth fault relay.

 

[telectrix]

and a metal grid if element does not have integral earthing.

 

[specs]

just trying to look it up

 

[shazbutz]

Cheers Telectrix. Looking forward to a chat with there tech team....

 

[specs]

Cheers Telectrix. Looking forward to a chat with there tech team....

Not sure if this helps or not. but its all I could find on the subject. I have never heard or seen the one you describe and would be interested to hear the outcome.

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Earthing Grid





You are here: Home » FAQs » Heat Mat Glossary » Earthing Grid
An earthing grid is a metallic structure that must be installed above an unsuitably earthed heating system when it is used in a wet area such as a bathroom. The earthing grid is connected to an RCD and this ensures that the system is switched off if there is damage to the floor.
In bathrooms it is a legal requirement to place earthing grids above many systems if including carbon films, some heating ribbons and any normal heating cables if they are not fully earth protected. Earthing grids add to the cost and time of an installation and it is always preferable to use a system with a fully integrated earth rather than having to install a separate earthing grid.

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Tel: 01444 247020

 

[shazbutz]

The more I read the more that it is as simple as 753.411.3.2. Good job the floor is far from fully down and is floating. The natural progression on this question now - where do I get the 30mm grid. Just searched CEF and local independent wholesaler with no joy.

 

[specs]

So what did the tech dept say. they must have answered the phone by now

 

[specs]

I am interested in this as I have never come across a system without an earth, and I find it hard to believe that anyone would choose a system that would require an earth grid purely on cost grounds.

 

[shazbutz]

It's a long story! The Swedish manufacturers, despite multiple emails from me requesting an answer from their technical and design team failed to respond at all. The UK team's answer was pretty much no earthing arrangements as long as not in a wet room and must be protected by a 30mA RCD. When I pushed the requirements stated in BS7671, the response was pretty much; " yeah we have had a few enquiries about that but an earthing grid is not required."
The system was not selected on cost but the most appropriate for the construction of the kitchen floor and layout. The grid went in but played hell with the previously established levels so there was much huffing and puffing from the builder. I remain surprised that there is no reference to earthing in promotional clips, installation instructions or in quite a long YouTube video of an installation. Lesson learned!