RCD test button not tripping the RCD.


R

Rednadnerb

Hi all
After working OK since it was installed a couple of months ago the RCD
started tripping whenever anything was switched on.
After failing to isolate the problem by disconnecting circuits we (the
installer and I) realised that the RCD test button doesn't work, so
after a quick dash to Screwfix we got an identical one and installed
it but it's exactly the same! pressing the yellow test button does
nothing. Could it be we have two faulty RCD's or is there something
we're obviously missing?
 
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A

Andrew Gabriel

Hi all
After working OK since it was installed a couple of months ago the RCD
started tripping whenever anything was switched on.
After failing to isolate the problem by disconnecting circuits we (the
installer and I) realised that the RCD test button doesn't work, so
after a quick dash to Screwfix we got an identical one and installed
it but it's exactly the same! pressing the yellow test button does
nothing. Could it be we have two faulty RCD's or is there something
we're obviously missing?
Does the RCD have an earth connection? (Most don't, but a few do.)
If it does, I might guess the earth connection is faulty.
 
T

tony sayer

com> said:
Hi all
After working OK since it was installed a couple of months ago the RCD
started tripping whenever anything was switched on.
After failing to isolate the problem by disconnecting circuits we (the
installer and I) realised that the RCD test button doesn't work, so
after a quick dash to Screwfix we got an identical one and installed
it but it's exactly the same! pressing the yellow test button does
nothing. Could it be we have two faulty RCD's or is there something
we're obviously missing?
I might be wrong but you haven't got the input and output's reversed?.

Or a Neutral to Earth short?...
 
R

Rednadnerb

You got it, a neutral to earth short.
We weren't thorough with our checks, it turned out to be a neutral
wire trapped between the faceplate and the backbox.
Thanks to you both.

Brendan.
 
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J

js.b1

Do test RCD (or RCBO often).

I nearly got caught out in April 2009 when I cut through an outdoor
cable.
My spine is usually rough (left front quadrant spinal muscle is
essentially missing on an MR scan) so I will drop anything if I sense
problems. On that day I did drop some aluminium, severing a cable, the
RCBO did not trip. I only knew because the cable steamed the puddle I
was standing in. The RCBO would not trip by test button, it had been
tested one year before and all figures were exactly in line with
others & expectations).

Aside - having seen similar RCBO failures, they all ran signficantly
warmer to those nearby. To the extent that a palm run along the top of
the RCBO body (CU lid on) was "point hot". Terminal tightness was not
an issue, nor load (unloaded).
 

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