My RCCD trip yesterday evening and I have narrowed it down to the down
stairs ring main but having unplugged everything it still trips. I have
also disconnected the central heating and kitchen fan at the spur box
but it still trips.
That only leaves the built in oven which I think is connected by a spur
so if it isn't that I am at a loss. I should be able to get to where
the spur for the oven breaks out from the ring but I don't see why this
should suddenly have gone as it wasn't in use at the time.
I can only assume that the next course of action is to progressively
disconnect sections of the ring between junction boxes to highlight
where the fault lies?
Is there anything else I should try before I call in a sparks?

Kevin

"Kev" wrote in message
oups.com...
My RCCD trip yesterday evening and I have narrowed it down to the down
stairs ring main but having unplugged everything it still trips. I have
also disconnected the central heating and kitchen fan at the spur box
but it still trips.
That only leaves the built in oven which I think is connected by a spur
so if it isn't that I am at a loss. I should be able to get to where
the spur for the oven breaks out from the ring but I don't see why this
should suddenly have gone as it wasn't in use at the time.
I can only assume that the next course of action is to progressively
disconnect sections of the ring between junction boxes to highlight
where the fault lies?
Is there anything else I should try before I call in a sparks?

Kevin

Sounds like you're almost there. I would check insulation and proximity of L
and N wiring in downstairs ring-main boxes and junctions in case one is
inadvertently touching E.
Also look for any water moisture or dampness seeping near bare conductors,
which fault condition would trigger a tripping.
Jim

On Mon, 12 Dec 2005 09:31:04 GMT, "Jim Gregory"
wrote:

"Kev" wrote in message
roups.com...
My RCCD trip yesterday evening and I have narrowed it down to the down
stairs ring main but having unplugged everything it still trips. I have
also disconnected the central heating and kitchen fan at the spur box
but it still trips.
That only leaves the built in oven which I think is connected by a spur
so if it isn't that I am at a loss. I should be able to get to where
the spur for the oven breaks out from the ring but I don't see why this
should suddenly have gone as it wasn't in use at the time.
I can only assume that the next course of action is to progressively
disconnect sections of the ring between junction boxes to highlight
where the fault lies?
Is there anything else I should try before I call in a sparks?

Kevin

Sounds like you're almost there. I would check insulation and proximity of L
and N wiring in downstairs ring-main boxes and junctions in case one is
inadvertently touching E.
Also look for any water moisture or dampness seeping near bare conductors,
which fault condition would trigger a tripping.
Jim



Might also simply be a socket fixing screw having finally gone
through some insulation.

Andy

In article .com,
Kev wrote:
My RCCD trip yesterday evening and I have narrowed it down to the down
stairs ring main but having unplugged everything it still trips. I have
also disconnected the central heating and kitchen fan at the spur box
but it still trips.
That only leaves the built in oven which I think is connected by a spur
so if it isn't that I am at a loss. I should be able to get to where
the spur for the oven breaks out from the ring but I don't see why this
should suddenly have gone as it wasn't in use at the time.
I can only assume that the next course of action is to progressively
disconnect sections of the ring between junction boxes to highlight
where the fault lies?
Is there anything else I should try before I call in a sparks?

How did you 'narrow' it down? Simply switching off an MCB doesn't disable
that circuit as far as an RCD is concerned - a neutral to earth fault will
still trip it. The only way to truly disable the circuit is to disconnect
line and neutral.

By far and away the likely cause is a faulty mineral insulated heating
element. To be found in immersions, washing machines etc and ovens.

--
*Stable Relationships Are For Horses.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

How did you 'narrow' it down? Simply switching off an MCB doesn't disable
that circuit as far as an RCD is concerned - a neutral to earth fault will
still trip it. The only way to truly disable the circuit is to disconnect
line and neutral.

By far and away the likely cause is a faulty mineral insulated heating
element. To be found in immersions, washing machines etc and ovens.

--
*Stable Relationships Are For Horses.

Dave Plowman London SW
To e-mail, change noise into sound.
I flicked off each MCB then switched them on in turn, as soon as the
down stairs ring mcb is switched the RCCD trips out. I must admit that
I was surprised that it was the down stairs ring as it is usually a
circuit for the garden with pond pumps that trips. Failing that it has
always been the kettle or the wife's rice cooker so having disconnected
everything I am puzzled why it still trips.

Kevin

Kev wrote:
Dave Plowman (News) wrote:

How did you 'narrow' it down? Simply switching off an MCB doesn't disable
that circuit as far as an RCD is concerned - a neutral to earth fault will
still trip it. The only way to truly disable the circuit is to disconnect
line and neutral.

By far and away the likely cause is a faulty mineral insulated heating
element. To be found in immersions, washing machines etc and ovens.

--
*Stable Relationships Are For Horses.

Dave Plowman London SW
To e-mail, change noise into sound.
I flicked off each MCB then switched them on in turn, as soon as the
down stairs ring mcb is switched the RCCD trips out. I must admit that
I was surprised that it was the down stairs ring as it is usually a
circuit for the garden with pond pumps that trips. Failing that it has
always been the kettle or the wife's rice cooker so having disconnected
everything I am puzzled why it still trips.

Kevin

This effect can be deceptive.

I had a similr problem and thought that I had narrowed it down as well.
As it turned out, the only only reason that the RCCD tripped was
because of the MCB load suddenly appeared on the RCCD [and the load
only needs to be marginally out of balance (before it settles) to trip
out the RCCD!]

Thus giving a false impression.

There is no easy way without a megger (which is the way I did it in the
end).

Cheers

Peter

Dave Plowman (News) pretended :
How did you 'narrow' it down? Simply switching off an MCB doesn't disable
that circuit as far as an RCD is concerned - a neutral to earth fault will
still trip it. The only way to truly disable the circuit is to disconnect
line and neutral.

Just to qualify that a little....

If the RCD can be made to reset by turning MCB's off, the one which
does cause it to trip as it is turned on will most likely protect the
circuit with the problem.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk