underfloor heating and part p

[abz2002]

Hello all

first post!



Just installed a 4m2 undertile heating mat (about 200w in all) and wired in the digital thermostat outside the bathroom via a 30ma RCD.

All is well and heats up nicely.

Trouble is I didn't realise that this requires part p

what options do I have other than to rip up the floor and start again?

1) can a 'competent person' come and check the installation of the thermo and RCD, make any adjustments they think necessary and self certify as their own work?

2) If I get the council to come and look at it now as retro planning application, will they want to see the layout of the mat or would they be happy seeing the wiring to the thermostat and RCD only?

As the cabling is pre installed on the mat, the 50mm gap has been observed and there are no crossing over etc etc so I'm happy with my installation. As there is an RCD surely thats all they should be interested in if they were to inspect?

Any help much appreciated.

 

[ModernMaterials]

This is such a grey area: Particualrly the 'competent person' aspect.

a) you could stay silent and forget about this, happy in the knowledge that you have done a safe and competant job.

b) you could seek certification... and to be honest i think the best thing would be to bite the bullet and get the B.C. inspector in explain exactly what you have done and hope for the best.

to answer your questions:

1)a competent person is not a part p qualified electrician who by definition does not have to be described as such. a competant person could be an electrician who has not yet passed part p or indeed it could be you, yourself.

2) god knows! it varies from region to region. when i enquired about a job i wanted to do in my kitchen, it transpired that they wouldnt even be interested in checking to see if an earth was present.

 

[Dippy]

Sounds like you know what you are doing and have done a safe job. So the only issue you face is IF you need to provide certification details in the future. The only reason for this is maybe for insurance purposes or if you come to sell the property and the buyer wants to see such certification (or if the HIPS law requires it then). However also remember that a periodic inspection should be done at appropriate intervals, so maybe you can just get it certified when you next have a PIR done.

Out of interest, how do you operate the heating? Is it on a timer or do you need to turn it on manually? I have toyed with the idea of underfloor heating but have dismissed it as the hot-water type is a PIA to retrofit and the electric type can be expensive to run...

 

[abz2002]

Update: Just rung a few sparkies up in the local area having selected them from the niceic.com website.

Great news is that for £280 this one guy will put in a new consumer unit (a good branded one Wylex or MK etc) which I desperately need as mine is 25 years old and he will ensure all bathroom bonding is OK, he will check continuity in my underfloor heating installation and provide 'self certification' for the lot.

I couldnt't believe the price! Others quoted £450 upwards plus £80 for each area that may need bonding!!

I'm booked in for a couple of weeks time and if anyones interested I can pass on his details. Surrey area.

Dippy, the underfloor heating was relatively straightforward to fit but requires a little experience with wiring. I got a 2m (4m2) tile-it mat from B&Q for £85 and a tile-it thermostat for £28 off ebay (£70 in B&Q!). The thermostat is digital and 7 day programmable.

Wiring was straighforward, once mat is laid using the self sticky backing (you can lift and resit many times before adhesive goes down), you simply ensure that there is at least 50mm gap between the element cable which is straightforward as its done for you, only time to watch this is where you cut the mat to change direction on the flooring. Drill a 10-12mm hole out of the bathroom to a position where you can fit thermostat and take the two 'cold end' cables through it. Then cut a trench in the plywood to seat the supplied conduit where the thermostat cable sits between two of the elements.

Test the resistance of the thermostat cable before and after installaton - very simple with a cheap multimeter -set to k omhs and ensure reading falls between 8-12.

Other installations may vary but this brand had simple and clear instructions.

I had a redundant 13a spur from an old towel rail install so sat the thermo in that and the RCD next to it where a single socket existed so not digging out for boxes!

unless the supply you hook up to has one at the consumer unit, a 30ma RCD is 'recommended'. I didnt have one given age of consumer unit so bought a standalone one off ebay for £25 but when consumer unit gets updated I shall take it off and put the single socket back on.

All in all 6 connections to the thermostat box and 2 for earth, 2 L and N feed via the RCD, 2 L and N for the mat (load), 2 for the thermostat cable which can be wired either way round, 2 for the earth from the mat don't actually attach to thermo but to the earth from the RCD feed and to the back box for added piece of mind.

I have programmed it such that it comes on in the morning and evenings during the week and all day at weekends (26 degrees). All other times is goes into 'economy' mode and I've set that at 21c. Simple to programme as instructions very clear.

For larger areas I guess you're right electric may be expensive but for a 2x2 bathroom I had no issues with running costs. Also the programmer I bought is apparently 'intelligent' as it has 5 heat settings so will only apply the least amount of heat required to bring up to the required temperature and also adjust the times it comes on and off depending on past patterns?!

I only went for it to take the chill off porcelain tiles and at 26c you can hardly tell its on (28 is much better but not necessary) but when the proper chill comes I'm sure even 26c will be appreciated!

 

[DESL]

Great news is that for £280 this one guy will put in a new consumer unit (a good branded one Wylex or MK etc) which I desperately need as mine is 25 years old and he will ensure all bathroom bonding is OK, he will check continuity in my underfloor heating installation and provide 'self certification' for the lot.

I couldnt't believe the price! Others quoted £450 upwards plus £80 for each area that may need bonding!!

Seems a bit cheap for Surrey depends a lot on the size of your house whether there is any remedial work required (undoing dodgy diy) that might appear as extras on the final invoice.
I also hate to say what level of inspection and testing will be carried out for the price. I usually allow a full day for a CU change but must admit that a lot of time is wasted identifying circuits.

 

[Softus]

I don't understand how he can do it for that amount of money. I would be suspicious of the extent of testing he'll do, the amount of bringing-bonding-up-to-standard, and the verify of his claim of being registered.

You did ask him if he was registered, didn't you?

Edit: oh b*gger, I was just pipped to that one.

 

[Steve]

This is what you get for £200 in Doncaster south yorkshire.

Not pretty. I wouldnt expect any better for £280 down south.

I'd rather have accepted the £450+ quotes.

And you dont "deperately" need a new CU. 25 years isnt ancient, as CU's go. Least it wont have a wooden back

 

[Softus]

This is what you get for £200 in Doncaster south yorkshire.

Oh. My. God.

 

[megawatt]

My wife could do a better job than that

 

[Softus]

My wife could do a better job than that

She certainly can.

 

[Steve]

This is what you get for £200 in Doncaster south yorkshire.

Oh. My. God.

Thought you'd like it Softus

 

[JohnD]

we all know that was really done by a young lad called Crafty.

 

[Softus]

Actually I was a bit hasty in my assessment. After studying the photo again I can now see one conductor that's neatly terminated.

BTW, do those two black wires from the third MCB really go straight to the protected neutral busbar?

 

[Steve]

BTW, do those two black wires from the third MCB really go straight to the protected neutral busbar?

No. they go behind that MCB. Said MCB is spare.

we all know that was really done by a young lad called Crafty.

Nope. My workmanship was saved for the shed.

 

[Softus]

Said MCB is spare.

Steve, it was a joke. Or, as they (reputedly) say in Yorkshire - it were a joke lad. Aye, 'appen.