Underfloor Heating - 13amp fused spur or plug

[hanrahan]

I have some underfloor heating (electrical) for my kitchen which i am planning on fitting myself, the instrutions say to run the power from a fused spur, via the thermostat. as part of the the instructions it says to test the heating (loose cable) with a multimeter or to use a fused plug for a few mins to check it works.

so here are my questions:
1) on a multi meter is resistance the Ohms sign?
2) if i can test it via a fused plug to test the underfloor heating why can't I just use a plug to power the underfloor heating rather than via a fuse spur (which i understand is essentially the same thing)? would this then comply with 17the Edition? (i will RCD the SPUR or PLUG)
3) what test (setting) do i need to have my multimeter on to check that the plug I will either use or spur of is not already a spur?

The kitchen is RCD protected and has been tested recently during a kitchen installation

sorry for all the questions - thanks for your time

 

[ColJack]

1 - yes...
2 - because a plug is not used for a permanent fixture, what would be the point? it's not like you can move it once it's tiled in... and you need to connect it inline with the stat for it, a fused spur is a nice convenient place to put the connections in the back of the box..
3 - you don't.. you need to trace it back..

if it has one cabke, it's likely a spur.. ( but not definite.. if it's on a 32A breaker then it's a spur.. if it's on a 20A or 16A breaker then it's a radial )
if it has 2 wires and is on a 32A breaker it's very likely part of the ring..
to test if it IS on part of a ring, seperate the 2 cables and put into connector blocks, ie 6 seperate wires..( with the power off obviously )..
then turn the power back on and test the 2 cables for live ( AC volts setting on the meter ) between it's live and earth cable, and live and neutral cable..

if you only get live on 1 cable then it's a radial ( from a ring if it's on a 32A breaker ) and is a bad sign anyway..

 

[skenk]

... the instrutions say...to use a fused plug for a few mins to check it works.

1) on a multi meter is resistance the Ohms sign?

Yes

2) if i can test it via a fused plug to test the underfloor heating why can't I just use a plug to power the underfloor heating rather than via a fuse spur (which i understand is essentially the same thing)? would this then comply with 17the Edition? (i will RCD the SPUR or PLUG)

No because to comply you have to follow the manufacturers instructions

3) what test (setting) do i need to have my multimeter on to check that the plug I will either use or spur of is not already a spur?

Low ohms, test between both legs of L, N & E (POWER OFF @ MAIN SWITCH) you can check your recent test paperwork as well - there should be no spurs off spurs

I expect this work will need to be notified to LABC before you commence etc etc

 

[ColJack]

actually yeah, skenk's way of testing for a ring is safer...
don't know what I was thinking...

 

[bongos]

1) on a multi meter is resistance the Ohms sign?

Yes

2) if i can test it via a fused plug to test the underfloor heating why can't I just use a plug to power the underfloor heating rather than via a fuse spur (which i understand is essentially the same thing)? would this then comply with 17the Edition? (i will RCD the SPUR or PLUG)

You should use a fused spur with the relevant fuse in it, as stated by the MI. If you fail to follow the MI then you may invalidate the warranty. I don't think there would actually be anything technically wrong with using a plug on the end but a FCU would be far better in my opinion. You say that you will "RCD the spur or plug" but if this circuit is already protected by a 30mA RCD (you say it is protected by a RCD but not what rating) then this would not be necessary.

3) what test (setting) do i need to have my multimeter on to check that the plug I will either use or spur of is not already a spur?

You would need to measure the resistance at all the sockets on the ring. They should all be of a similar reading. Those that are on a spur will be substancially higher. However, by the use of a FCU you would be limited to a maximum of 13A on a spur anyway.

Notify to your LABC before you start work.

EDIT: Far too slow!

 

[skenk]

Hey, it's late, and with your current post rate (& speed of reply ) you're bound to make a mistake every now and then!

 

[bongos]

Hey, it's late, and with your current post rate (& speed of reply ) you're bound to make a mistake every now and then!

Sounds about right. I normally seem to arrive when everyone's tidying up and leaving...

 

[ColJack]

i think that was aimed at me... but welcome to the party.. the beers all gone but we got some pernod round here somewhere.. and there's half a bottle of brandy left over from christmas somewhere...

 

[GaryMo]

would this then comply with 17the Edition?

I recommend you seek out a copy of BS7671:2008 and read Secion 753 on the requirements of floor and ceiling heating systems if you want compliance.
There's quite a bit of information you need to document.

Col - I've just polished off the red wine so that's out as well!

 

[ColJack]

err.. we didn't have any red.... white wine with pork..
there was some red-x under the sink though...

 

[GaryMo]

 

[ColJack]

or if it was in the fridge, it might be that bottle of cranberry juice that's been in there since july.. that might have fermented by now...

 

[ban-all-sheds]

I have some underfloor heating (electrical) for my kitchen which i am planning on fitting myself

When you made your application for Building Regulations approval, what did you say would be the way you'd comply with P1?