Sitting here drinking my coffee about an hour ago, when 'click' the
sockets power goes off.

There are 4 sockets circuits, 3 each have their own RCBO, one via a
separate 100ma time delayed RCD. In a new CU installed about a year ago,
no problems since then. TT earth.

All three RCBO's had switched off.

Turned them back on, and everything is fine, but left wondering why all
3 would go off like that together
--
Chris French

In article ,
chris French writes:
Sitting here drinking my coffee about an hour ago, when 'click' the
sockets power goes off.

There are 4 sockets circuits, 3 each have their own RCBO, one via a
separate 100ma time delayed RCD. In a new CU installed about a year ago,
no problems since then. TT earth.

All three RCBO's had switched off.

Turned them back on, and everything is fine, but left wondering why all
3 would go off like that together

Some RCDs/RCBOs also trip on other fault conditions, such as
disconnected neutral (requires that the device has an earth
tail connection). It may also be that some type of voltage
spike triggered them, either on the supply, or in the ground
where your rod is (will look like a disconnected neutral),
due to someone else's earth fault or lightning strike.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

chris French wrote:
Sitting here drinking my coffee about an hour ago, when 'click' the
sockets power goes off.

There are 4 sockets circuits, 3 each have their own RCBO, one via a
separate 100ma time delayed RCD. In a new CU installed about a year ago,
no problems since then. TT earth.

All three RCBO's had switched off.

Turned them back on, and everything is fine, but left wondering why all
3 would go off like that together
Earth neutral short?

On Mar 9, 11:40*am, chris French
wrote:
Sitting here drinking my coffee about an hour ago, when 'click' the
sockets power goes off.

There are 4 sockets circuits, 3 each have their own RCBO, one via a
separate 100ma time delayed RCD. In a new CU installed about a year ago,
no problems since then. TT earth.

All three RCBO's had switched off.

Turned them back on, and everything is fine, but left wondering why all
3 would go off like that together
--
Chris French

Also, some are effected by transients in the mains (glitches or spikes
caused by faults elsewhere.)

harry wrote:
On Mar 9, 11:40 am, chris French
wrote:
Sitting here drinking my coffee about an hour ago, when 'click' the
sockets power goes off.

There are 4 sockets circuits, 3 each have their own RCBO, one via a
separate 100ma time delayed RCD. In a new CU installed about a year ago,
no problems since then. TT earth.

All three RCBO's had switched off.

Turned them back on, and everything is fine, but left wondering why all
3 would go off like that together
--
Chris French

Also, some are effected by transients in the mains (glitches or spikes
caused by faults elsewhere.)
Wrong. They are effected my manufacturers and electricians.

Transients may affect them, but never effect them, unless you are a
creationist.

On Mar 9, 6:00*pm, The Natural Philosopher
wrote:
harry wrote:
On Mar 9, 11:40 am, chris French
wrote:
Sitting here drinking my coffee about an hour ago, when 'click' the
sockets power goes off.

There are 4 sockets circuits, 3 each have their own RCBO, one via a
separate 100ma time delayed RCD. In a new CU installed about a year ago,
no problems since then. TT earth.

All three RCBO's had switched off.

Turned them back on, and everything is fine, but left wondering why all
3 would go off like that together
--
Chris French

Also, some are effected by transients in the mains (glitches or spikes
caused by faults elsewhere.)

Wrong. They are effected my manufacturers and electricians.

Transients may affect them, but never effect them, unless you are a
creationist.- Hide quoted text -

- Show quoted text -

http://en.wikipedia.org/wiki/Affect

On 09/03/2011 12:15, Andrew Gabriel wrote:

Some RCDs/RCBOs also trip on other fault conditions, such as
disconnected neutral (requires that the device has an earth
tail connection).

That's pretty-well all of the single-module solid-neutral types now.
They trip if the voltage between the neutral and functional earth tails
exceeds 50 volts (in practice about 42 volts for an MK branded one I
tested recently).

It may also be that some type of voltage spike triggered them, either
on the supply, or in the ground where your rod is (will look like a
disconnected neutral), due to someone else's earth fault or lightning
strike.

Agreed. I'd expect the RCBOs to have some low-pass filtering to protect
against tripping on 'spikes' (fast transients), so we're most likely
looking at a 'surge' on the supply neutral. As you say a line-earth
fault in the supply network or someone else's installation could lift
the neutral enough to do this.

--
Andy

Andy Wade wrote:
On 09/03/2011 12:15, Andrew Gabriel wrote:

Some RCDs/RCBOs also trip on other fault conditions, such as
disconnected neutral (requires that the device has an earth
tail connection).

That's pretty-well all of the single-module solid-neutral types now.
They trip if the voltage between the neutral and functional earth tails
exceeds 50 volts (in practice about 42 volts for an MK branded one I
tested recently).

It may also be that some type of voltage spike triggered them, either
on the supply, or in the ground where your rod is (will look like a
disconnected neutral), due to someone else's earth fault or lightning
strike.

Agreed. I'd expect the RCBOs to have some low-pass filtering to protect
against tripping on 'spikes' (fast transients), so we're most likely
looking at a 'surge' on the supply neutral. As you say a line-earth
fault in the supply network or someone else's installation could lift
the neutral enough to do this.

RCBOs work by monitoring the differential current between line and neutral.

If, anywhere within the installation, there is a neutral earth short,
some current will be diverted to the earth path.

If that causes a big earth spike with respect to the neutral anything
(and tehse dauys athats most electronics wit RFI filtering) that has an
AC path between live, neutral an earth, will screw with the balance and
cause things to trip.

As will a major sure on the live line.

On 10/03/2011 10:38, The Natural Philosopher wrote:

RCBOs work by monitoring the differential current between line and neutral.

Yes all types of RCD do that. Additionally the modern RCBOs also
monitor the voltage between neutral and earth, and trip if it exceeds 50
V, or if the neutral goes o/c.

If, anywhere within the installation, there is a neutral earth short,
some current will be diverted to the earth path.

Yes, but that won't cause tripping of other final circuits. Here three
final ccts tripped together. That's far more likely to be caused by a
common fault, viz. something causing earth and neutral to move more then
50 V apart. Bearing in mind that this is a TT-earthed installation it's
either something dumping current into the local earth electrode, or
something remotely lifting the neutral. The latter seems more likely
since local current diverted to earth should trip an RCD well before the
rise in earth potential reaches 50 V.

If that causes a big earth spike with respect to the neutral anything
(and tehse dauys athats most electronics wit RFI filtering) that has an
AC path between live, neutral an earth, will screw with the balance and
cause things to trip.

Those sorts of transients don't usually cause RCD tripping problems,
unless the situation is already marginal with respect to leakage. And
then they will only tend to affect a single circuit.

--
Andy

In message , Andy Wade
writes
On 10/03/2011 10:38, The Natural Philosopher wrote:

RCBOs work by monitoring the differential current between line and neutral.

Yes all types of RCD do that. Additionally the modern RCBOs also
monitor the voltage between neutral and earth, and trip if it exceeds
50 V, or if the neutral goes o/c.

If, anywhere within the installation, there is a neutral earth short,
some current will be diverted to the earth path.

Yes, but that won't cause tripping of other final circuits. Here three
final ccts tripped together. That's far more likely to be caused by a
common fault, viz. something causing earth and neutral to move more
then 50 V apart. Bearing in mind that this is a TT-earthed
installation it's either something dumping current into the local earth
electrode, or something remotely lifting the neutral. The latter seems
more likely since local current diverted to earth should trip an RCD
well before the rise in earth potential reaches 50 V.



Ok, thanks folks, some external event then seems likely. shall file it
away in list of odd things that have happened.

Though it didn't trip the 3 x lighting circuits or the boiler circuit
RCBO's
--
Chris French