For the last week we've had our RCD trip two or three times a day. We
can switch it back on immediately so we can't identify which circuit
the fault is on. We're not doing anything when it happens so we
presume it's something being switched on by thermostat. At present we
are trying to find out what is doing it by a process of elimatation.
Where possible we are unplugging things, keeping in mind not all 13amp
sockets have double pole switches, and the fault could be neutral-
earth. However it's like trying to prove a negative. Has anybody any
ideas of any other way of finding out what it is, and why does the
fault disappear so quickly? The consumer unit is fairly new, and the
RCD covers everything.

Richard

On 18 Feb 2007 04:34:49 -0800, "fido" mused:

For the last week we've had our RCD trip two or three times a day. We
can switch it back on immediately so we can't identify which circuit
the fault is on. We're not doing anything when it happens so we
presume it's something being switched on by thermostat. At present we
are trying to find out what is doing it by a process of elimatation.
Where possible we are unplugging things, keeping in mind not all 13amp
sockets have double pole switches, and the fault could be neutral-
earth. However it's like trying to prove a negative. Has anybody any
ideas of any other way of finding out what it is, and why does the
fault disappear so quickly?

Could try testing everything, with the correct meters. May need to
find yourself an electrician for this bit.

The consumer unit is fairly new, and the
RCD covers everything.

Think that may need attention, depending on what type and why.
--
Regards,
Stuart.

fido wrote:

Has anybody any ideas of any other way of finding out what it is, and
why does the fault disappear so quickly?

Appliance faults are more likely than fixed wiring faults. The usual
suspects are immersion heater, washing machine and dishwasher heaters,
fridges and freezers. If you can, try isolating those things in turn
and see if the problem goes away.

The consumer unit is fairly new, and the RCD covers everything.

Oh dear, single 30 mA whole-house RCD? That's no longer considered
acceptable practice.

--
Andy

On 18 Feb, 14:17, Andy Wade wrote:
fido wrote:
Has anybody any ideas of any other way of finding out what it is, and
why does the fault disappear so quickly?

Appliance faults are more likely than fixed wiring faults. The usual
suspects are immersion heater, washing machine and dishwasher heaters,
fridges and freezers. If you can, try isolating those things in turn
and see if the problem goes away.

The consumer unit is fairly new, and the RCD covers everything.

Oh dear, single 30 mA whole-house RCD? That's no longer considered
acceptable practice.

--
Andy

Thanks for all the answers. It's rented property and we don't want to
get the landlord involved until we can find out what it is in case
it's one of our appliances. If it's the immersion heater then it's
their problem.

Richard

On 18 Feb, 17:14, "fido" wrote:
On 18 Feb, 14:17, Andy Wade wrote:
fido wrote:

Has anybody any ideas of any other way of finding out what it is, and
why does the fault disappear so quickly?

Appliance faults are more likely than fixed wiring faults. The usual
suspects are immersion heater, washing machine and dishwasher heaters,
fridges and freezers. If you can, try isolating those things in turn
and see if the problem goes away.

The consumer unit is fairly new, and the RCD covers everything.

Oh dear, single 30 mA whole-house RCD? That's no longer considered
acceptable practice.

--
Andy

Thanks for all the answers. It's rented property and we don't want to
get the landlord involved until we can find out what it is in case
it's one of our appliances. If it's the immersion heater then it's
their problem.

Richard

The logical thing is to check all your plugin appliances with a
multimeter, which will pick up close to 100% of earth leakage faults,
if not quite all. Test for any conduction from E to L&N.


NT

On Sun, 18 Feb 2007 13:29:31 +0000, Owain wrote:

Whole-house RCDs are contrary to Regulations.

Not quite true. They are required when the earth loop impedance is too
high to allow overload devices to trip quick enough. In which case the
whole installation RCD is 100mA time delayed rather than a normal 30mA
"fast".

The OP just states "RCD" he doesn't give any further information.

--
Cheers
Dave. pam is missing e-mail

wrote:

The logical thing is to check all your plugin appliances with a
multimeter, which will pick up close to 100% of earth leakage faults,
if not quite all.

I was looking at a fridge-freezer yesterday: insulation resistance
according to Fluke 77 multimeter ~ 6 Megohm, according to 500 V Megger
100 kohm. (The leakage turned out to be in the defrost heater.)

This is nothing like as rare as you're trying to suggest.

--
Andy

On 18 Feb, 14:17, Andy Wade wrote:
fido wrote:
Has anybody any ideas of any other way of finding out what it is, and
why does the fault disappear so quickly?

Appliance faults are more likely than fixed wiring faults. The usual
suspects are immersion heater, washing machine and dishwasher heaters,
fridges and freezers. If you can, try isolating those things in turn
and see if the problem goes away.

The consumer unit is fairly new, and the RCD covers everything.

Oh dear, single 30 mA whole-house RCD? That's no longer considered
acceptable practice.

--
Andy

yes... my wife got caught out yesterday evening with the torch in the
wrong place
stil eliminating items

On 19 Feb, 09:46, Andy Wade wrote:
wrote:
The logical thing is to check all your plugin appliances with a
multimeter, which will pick up close to 100% of earth leakage faults,
if not quite all.

I was looking at a fridge-freezer yesterday: insulation resistance
according to Fluke 77 multimeter ~ 6 Megohm, according to 500 V Megger
100 kohm. (The leakage turned out to be in the defrost heater.)

This is nothing like as rare as you're trying to suggest.

--
Andy

I didnt say what you describe is rare, I said failure to detect
leakage is the exception. When testing appliances with a mulitimeter,
write down the figures and zero in afterwards on the main suspects.

One always need be aware that leakage often worsens as V rises,
perhaps I should have mentioned that rather than assume.


NT

On 18 Feb, 22:13, "Dave Liquorice" wrote:
On Sun, 18 Feb 2007 13:29:31 +0000, Owain wrote:
Whole-house RCDs are contrary to Regulations.

Not quite true. They are required when the earth loop impedance is too
high to allow overload devices to trip quick enough. In which case the
whole installation RCD is 100mA time delayed rather than a normal 30mA
"fast".

The OP just states "RCD" he doesn't give any further information.

--
Cheers
Dave. pam is missing e-mail

it is a 30ma trip and I'm still having problems