On Thu, 2 Feb 2012 18:53:15 -0000, "Mortimer" wrote:

I suppose the element had developed a pinhole in the outer metal sheath
which would have tripped an RCD in a modern house long before the fault
worsened to the point that it blew a 30A fuse and left black stains all over
the fuse box.

I'm now inclined to wire immersions through their own RCD or RCBO, for
exactly that reason. A couple of times it's been useful, giving
warning of failure without any drama.

wrote in message
...
On Thu, 2 Feb 2012 18:53:15 -0000, "Mortimer" wrote:

I suppose the element had developed a pinhole in the outer metal sheath
which would have tripped an RCD in a modern house long before the fault
worsened to the point that it blew a 30A fuse and left black stains all
over
the fuse box.

I'm now inclined to wire immersions through their own RCD or RCBO, for
exactly that reason. A couple of times it's been useful, giving
warning of failure without any drama.


The main thing is that you need just the bad circuit to trip. The one
problem with RCDs is that they tend to take *everything* out and shut the
whole house down, which is bloody annoying if it happens when you are out
and the freezer defrosts or TV programmes aren't recorded. Ideally (if cost
wasn't an object) you need each circuit to have its own RCD which is set to
be more sensitive than a master RCD which is there only as a safety net in
case the individual RCD doesn't trip.

In article , Mortimer
wrote:
wrote in message
...
On Thu, 2 Feb 2012 18:53:15 -0000, "Mortimer" wrote:

I suppose the element had developed a pinhole in the outer metal sheath
which would have tripped an RCD in a modern house long before the fault
worsened to the point that it blew a 30A fuse and left black stains all
over the fuse box.

I'm now inclined to wire immersions through their own RCD or RCBO, for
exactly that reason. A couple of times it's been useful, giving warning
of failure without any drama.


The main thing is that you need just the bad circuit to trip. The one
problem with RCDs is that they tend to take *everything* out and shut the
whole house down, which is bloody annoying if it happens when you are
out and the freezer defrosts or TV programmes aren't recorded. Ideally
(if cost wasn't an object) you need each circuit to have its own RCD
which is set to be more sensitive than a master RCD which is there only
as a safety net in case the individual RCD doesn't trip.

The 'individual' RCD is the one preferred in the current Wiring
Regulations. I admit to having a "whole house" RCD - installed in the
early '80s.

--
From KT24

Using a RISC OS computer running v5.16

In message ,
writes
I'm now inclined to wire immersions through their own RCD or RCBO, for
exactly that reason. A couple of times it's been useful, giving
warning of failure without any drama.
What is an RCBO?
--
Clive

On Thu, 9 Feb 2012 15:42:40 +0000, Clive
wrote:

In message ,
writes
I'm now inclined to wire immersions through their own RCD or RCBO, for
exactly that reason. A couple of times it's been useful, giving
warning of failure without any drama.
What is an RCBO?

http://en.wikipedia.org/wiki/Residual-current_device

A Residual Current Circuit Breaker with Overload protection (RCBO)
combines the functions of overcurrent protection and leakage
detection.

--
Peter Duncanson
(in uk.tech.digital-tv)

On Thu, 9 Feb 2012 15:42:40 +0000, Clive
wrote:

What is an RCBO?

Really Cheap Bicycle Object

A combined Residual Current Device and Min Circuit Breaker -
Residual Current Circuit Breaker w/Overload protection.
Really should be RCCBO, but there you go.
http://en.wikipedia.org/wiki/Residual-current_device