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- 27 Sep 2004
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Had a look at some electric underfloor heating tonight causing RCD to trip.
It has only recently been installed and all metered ok when fitted a couple months ago. Has been working fine since, the place is still undergoing building work.
RCD trips instantly when heating is turned on on the stat. Meggered to start with at 250v and had 200M to earth. All ok I thought. Tried it at 500V, and got 0.00M. Tried again at 250V and still now at 0.00M.
The chippy there said that one tack nail when fitting the wooden flooring was put in the wrong place, so he showed me which nail it was, it was near where the UFH element runs. Put megger to the nail and to the live conductors, got 1.3M. Other nails near by up to around 70M.
Thinking the nail may have hit the element, we took up the floor, no damage was visible, however now the reading L-E and N-E is back to 200M at 250V.
Tried plugging it back in without the thermostat just straight on a plug top, and RCD tripped again.
Continuity of the element is at 16ohms.
Any ideas?
It has only recently been installed and all metered ok when fitted a couple months ago. Has been working fine since, the place is still undergoing building work.
RCD trips instantly when heating is turned on on the stat. Meggered to start with at 250v and had 200M to earth. All ok I thought. Tried it at 500V, and got 0.00M. Tried again at 250V and still now at 0.00M.
The chippy there said that one tack nail when fitting the wooden flooring was put in the wrong place, so he showed me which nail it was, it was near where the UFH element runs. Put megger to the nail and to the live conductors, got 1.3M. Other nails near by up to around 70M.
Thinking the nail may have hit the element, we took up the floor, no damage was visible, however now the reading L-E and N-E is back to 200M at 250V.
Tried plugging it back in without the thermostat just straight on a plug top, and RCD tripped again.
Continuity of the element is at 16ohms.
Any ideas?