Wiring up underfloor heating - PICS ADDED

[electronicsuk]

Consumer Unit

OK, so we can see that the sockets in your house are protected by a 30mA RCD. This is good news as, aside from the fact that it is required for the underfloor heating, it will also mean you don't need to worry about meeting the requirements for mechanical protection/burial depth that apply to non-RCD protected circuits under the 17th Ed.

Plaster Board cut away, 2 cold cables and sensor cable coming from
tiles and up into loft space. The cold and sensor cables will be installed
in plastic round conduit to be on the safe side

Looks as if you have a problem here with regard to safe zones, as once the plasterboard is back in place there will be no evidence as to the presence of the cables in that wall. If the stud wall is <=100mm then the placement of an electrical accessory vertically inline with the cables on either side of the wall may be sufficient to create a 'safe zone' for the cables, subject to certain conditions (follow link to the WiKi).

The alternatives are for the cable to be buried at a depth of >50mm (although it's hard to see how you'd manage that from either side, the wall doesn't look deep enough) or provide earthed mechanical protection by way of SWA cable/Pyro/earthed metal conduit, none of which are particularly practical in your case.

Bottom right of the picture, where i am pointing is a socket on the ring
with 1 in and 1 out. Could this be a possible socket to spur off from back
up into the loft ???

If you can confirm this socket is part of the ring final then yes, you can take a spur from it.

But then, when i had a brew and some brain food (Sausage & Egg butty)
i had another look at the set up and if you follow the level to the end,
directly opposite to that in the other room is a 1 gang socket, same hight
as end of level. This i thought might be perfect as all i would need to do
is cut more away of the plasterboard to expose the back of the socket
and spur off from this, though the battens and up the conduit with the
cold cables. Is this my best option or not chaps or am i barking up the
wrong tree ???

Again, if said socket if part of the ring final then you may spur from it. However, there will only be a horizontal safe zone extending from the existing socket, so you can't just run the cable horizontally and then take a 90 degree bend into the vertical and up into the loft without an accessory on the wall to create a vertical safe zone.

 

[electronicsuk]

John,

Just got off phone from manufacturer, nice chap and said that i can spur
off from an existing ring main (socket) and feed into loft space but it must be protected by a metal clad RCD - FCU unit
I presume its one of these
http://www.screwfix.com/prods/24825/Electrical-Supplies/RCDs/Volex-13A-RCD-FCU-Metal-Clad[/QUOTE]

Nice chap, but obviously doesn't know a lot about electrics. Firstly, as we have seen, the socket outlets in your house are already protected with a 30mA RCD at the consumer unit. There is absolutely no point in adding a second RCD to an already protected circuit.

I have absolutely no idea why you were told that it must be metal clad, even if an RCD protected FCU were needed, there would be no requirement for it to be metalclad or otherwise.

Right, i removed the plasterboard in corner, opposite to switch in other
room and located ring main and back box to socket



Is there anything stopping me from spurring from this socket using 2.5mm
T&E through battens and clipped, up through conduit with cold cables
and into loft to the RCD-FCU ??? Then from RCD-FCU down to thermostat
in wall ???
At least then i can replace plasterboard and my tiler can crack on with the
walls tommorow.

As per my previous post (I'm struggling to keep up with you!) you will need to consider the safe zones. If you have a read up on the bathroom zones in the WIKI at the same time then you may find that it will be permissible for the thermostat to be mounted in the bathroom directly above the cables from the heating mat. In that case, you can happily take a spur horizontally from the socket in the adjoining room, and the U/floor heating supply and probe cable cold cables can run vertically to the stat and FCU.

 

[Taylortwocities]

If you have a read up on the bathroom zones in the WIKI at the same time then you may find that it will be permissible for the thermostat to be mounted in the bathroom directly above the cables from the heating mat.

WarmUp instructions say their stat must not be inside the bathroom.

 

[electronicsuk]

If you have a read up on the bathroom zones in the WIKI at the same time then you may find that it will be permissible for the thermostat to be mounted in the bathroom directly above the cables from the heating mat.

WarmUp instructions say their stat must not be inside the bathroom.

They do indeed state "In the case of bathroom installations, electrical regulations prohibit the installation of the thermostat within the bathroom itself. In such cases, the thermostat should be fitted to the outside of an internal wall of the bathroom, as close to the undertile heating as possible, for example in an adjacent airing cupboard."

However, the electrical regulations don't actually prohibit the installation of a stat in the bathroom at all, so I can't see any problem with installing one in a permitted zone.

 

[Taylortwocities]

Just so long as its suitable for the environment. If it were me I'd follow the manufacturer's instructions.

 

[Kristoff28]

Mathew,

Many thanks for your input mate and bringing me to light on the
safe zone matter.

Had a good look at the wiki and yep i was well out the safe zone until i
remembered that i have a fan switch on that wall in close proximity of the
cables so went up to bathroom and took some pics.

This is the large cut out inside the bathroom. You can see the fan switch
above


This is more of a close up and what distance the switch is from the line
if cables, which is 170mm


Now would this me suitable mate and classed as a safe zone or would i
need to move the switch to a more inline approach with the cables ???

Also i contacted warmup regarding the position of the thermostat and
technical told me under no circumstances shoud the stat be positioned
inside the bathroom due to steam and moisture. He said it would
fail very quickly if the room gets steamy etc which mine does as its
only small and the fan aint to good either.

Thanks

Chris

 

[electronicsuk]

My interpretation of the regs is that the safe zone is only as wide as the accessory that created it. You can either re-route the cables or move the fan controller across a little, I wouldn't have thought the latter would be too much trouble?

Fair play on the manufacturers advice regarding the thermostat, it's just a shame that they chose to word the installation manual the way they did. Perhaps there is a seperate instruction sheet with the thermostat with more detailed information that would have covered this issue.

 

[Kristoff28]

Cheers matey
I will cut another hole in line with the studs and line up with the
existing switch with the cables or at least within 15mm of them.
It will be easier than re routing them as that was a ball ache.

cheers

Kris

 

[ban-all-sheds]

FYI - everything you ever wanted to know about concealed cable zones:

• http://www.voltimum.co.uk/files/gb/attachments/niu/l/attachments/c5-43.pdf
• http://web.archive.org/web/20061110111450/http://www.niceic.org.uk/downloads/concealedcables.pdf
• IEE article
• IEE Article on 17th Edition requirements for concealed cables.

 

[Kristoff28]

All sorted now

Sparky came round this morning and completed all works. He said i hadnt
done a bad job and was on the right track but just needed a few tweeks
to make it spot on.
He never moved the fan switch in the end, all he did was fit another back
box inline with cables, passed them through the box then fitted a blank
plate.
He also checked out my work that i did earlier this month when i fitted
some bathroom downlighters and blue LED lights, he made a few minor
adjustments and is now all passed.

He then fitted two outside lights to the back and side of my house aswell
as made everything ready to get power to my sheds later next month.

All for a grand total of £100

Im now a happy man

Many thanks for all your help lads

Kris

 

[ban-all-sheds]

All for a grand total of £100

For that, did he also lie to the council about him having done the work?

 

[Kristoff28]

All for a grand total of £100

For that, did he also lie to the council about him having done the work?

Friend of a friend BAS

Oh yeah and 24 cans of carling

 

[ban-all-sheds]

Personally I think you are a complete **** to be amused to have become part of a criminal conspiracy.

 

[Kristoff28]

Now Now dont get your G-String in a twist Mr Keyboard Warrior.

It cost me alot more than that, only put £100 cos i knew you would bite

HOOK - LINE - AND SINKER

HAPPY NEW YEAR

Topic Closed

 

[ban-all-sheds]

It comes as no surprise to find that you are also a liar, and pathetically inadequate.