Now on its knees ;-)

Just starting to move the kitchen spur, with the fuse out of the fuse box.

The whole house RCOCB tripped!

Put my meter on the wires, and Neutral and Earth seem the same, but there is
about 3V between the live and Neutral/Earth.

How worried should I be?

Is this likely to be induced current from loads of parallel wires, or
potetially something more serious?

The house was checked over by an electrician before the Combi boiler was
wired in.

TIA

Dave R

--

In article ,
"David W.E. Roberts" writes:
Now on its knees ;-)

Just starting to move the kitchen spur, with the fuse out of the fuse box.

The whole house RCOCB tripped!

Caused by you shorting the neutral and earth together
(or live and earth if there's a load still connected
to the circuit, which is connecting live to neutral).

How worried should I be?

Not worried -- it's normal.

Is this likely to be induced current from loads of parallel wires, or
potetially something more serious?

If you short the neutral to earth, some of the current
returning in the neutral from other circuits will be
diverted to earth, causing an imbalance at the RCD, so
it will trip.

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

"Andrew Gabriel" wrote in message
...
In article ,
"David W.E. Roberts" writes:
Now on its knees ;-)

Just starting to move the kitchen spur, with the fuse out of the fuse
box.

The whole house RCOCB tripped!

Caused by you shorting the neutral and earth together
(or live and earth if there's a load still connected
to the circuit, which is connecting live to neutral).

How worried should I be?

Not worried -- it's normal.

Is this likely to be induced current from loads of parallel wires, or
potetially something more serious?

If you short the neutral to earth, some of the current
returning in the neutral from other circuits will be
diverted to earth, causing an imbalance at the RCD, so
it will trip.

Thanks - I have now wrapped the bare ends in tape.

I hadn't realised that you could trip with the fuse out.

The message
from "David W.E. Roberts" contains these words:

Now on its knees ;-)

Just starting to move the kitchen spur, with the fuse out of the fuse box.

The whole house RCOCB tripped!

Put my meter on the wires, and Neutral and Earth seem the same, but there is
about 3V between the live and Neutral/Earth.

How worried should I be?

Is this likely to be induced current from loads of parallel wires, or
potetially something more serious?

The house was checked over by an electrician before the Combi boiler was
wired in.

The fuse (or MCB if that is what you have) just isolates the live side
of the circuit it serves. If you have equipment in use on other circuits
shorting the neutral to earth on the circuit you are working on will
allow some current to bypass neutral side of the RCD and the imbalance
will cause it to trip. BTDTGTTS.

Nanny will be along in a minute to tell you you *must never* work on
individual circuits without isolating the whole supply at CU main
switch. :-)

--
Roger Chapman

In article ,
David W.E. Roberts wrote:
Just starting to move the kitchen spur, with the fuse out of the fuse
box.

The whole house RCOCB tripped!

No need to be surprised - it looks for an imbalance between the current
flow on line and neutral, so if you short neutral to earth it'll trip
regardless of the fuse or whatever being removed.

--
*Why are a wise man and a wise guy opposites? *

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

On Sat, 04 Aug 2007 18:34:23 +0100, "Dave Plowman (News)"
mused:

In article ,
David W.E. Roberts wrote:
Just starting to move the kitchen spur, with the fuse out of the fuse
box.

The whole house RCOCB tripped!

No need to be surprised - it looks for an imbalance between the current
flow on line and neutral, so if you short neutral to earth it'll trip
regardless of the fuse or whatever being removed.

*Can* trip, they don't always. Depends on the difference in potential
between N + E.
--
Regards,
Stuart.

On Sat, 04 Aug 2007 18:51:17 +0100, Lurch wrote:

No need to be surprised - it looks for an imbalance between the current
flow on line and neutral, so if you short neutral to earth it'll trip
regardless of the fuse or whatever being removed.

*Can* trip, they don't always. Depends on the difference in potential
between N + E.

I was going to say that, a N E short doesn't cause an RCB trip here but
then the E is bonded to the N and into the real ground at the pole
outside...

--
Cheers
Dave. pam is missing e-mail

In article ,
Lurch wrote:
No need to be surprised - it looks for an imbalance between the current
flow on line and neutral, so if you short neutral to earth it'll trip
regardless of the fuse or whatever being removed.

*Can* trip, they don't always. Depends on the difference in potential
between N + E.

Yes - I suppose there's less likelihood on a PME installation. But I
doubt the OP has this with a fusebox.

--
*If at first you don't succeed, then skydiving definitely isn't for you *

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

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "David W.E. Roberts"
saying something like:

Now on its knees ;-)

That's offal. Still, I'm sure you'll get to the guts of the matter.
--

Dave