On 22/06/2015 19:28, wrote:
On Monday, 22 June 2015 15:47:38 UTC+1, John Rumm wrote:
On 22/06/2015 11:37, nt wrote:
On Monday, 22 June 2015 11:05:10 UTC+1, John Rumm wrote:
On 22/06/2015 09:56, Jim x321x wrote:
John Rumm wrote in
:

with the existing setup, and I rarely get any
inexplicable tripping of the circuit breakers. As far as
I am aware, the old fuse boxes (even when fuses contained
fuse wire) did what they were designed to do, with no
problems.

They did what they were supposed to - and will still do
so. The main thing your current setup lacks is RCD
protection.


Thanks to all for the excellently helpful advice.

If I added an RCD covering the entire house (without
replacing the existing fuse box which is already fitted with
MCBs, would that constitute a change to the wiring and thus
require building control notification?

Firstly you don't want a single RCD covering the whole house -
that is a practice that was common during the 15th edition, but
is deprecated now since it offers no "discrimination" in the
event of a fault (i.e. the fault will take out the supply to
the whole house, not just the circuit causing the problem). So
many circuits on one RCD are also more prone to nuisance
tripping in the first place.

A single RCD is moderately likely to not even work.

True, but the failure rate is not high enough to make that relevant
I would say. (IIRC, 15% of those that have never been tested may
fail to operate when they should - but that sill leaves 75% that
will work and potentially prevent an injury)

What I meant is in some cases you will have no power because the
install trips the RCD when powered

That's hardly an ongoing problem... it means you have either a fault, or
too much combined leakage. Both fixable, neither relevant since no one
will be fitting a single whole house RCD anyway.

So if your only reason for the change is to make the house
more saleable, I would not bother. If however you are planning
to carry on living there, then its worth it (IMHO) for other
reasons.

Work out the cost & size of risk reduction. Compare with other
options. The benefit per pound is far from top of the list.

If your only criterion is avoidance of death due to electrocution,
then the argument is plausible, since from a statistical point of
view you may as well ignore the risk of death - its low enough to
be insignificant.

Death risks all come with injury risks too. Its harder to get injury
risks, but if you tabulate them its still not a priority on the table
of preventable risks.

That is nonsense, as you are well aware.

None of that however diminishes the effectiveness of a RCD at
preventing shock injury - the occurrences of which are commonplace
rather than rare. (100's K of hospital admissions per year)

How do you conclude that all those are injuries?

These are the cases where either an ambulance was called or someone went
/ was taken to A&E.

They will include the full range of injuries from a mild burn - no real
treatment required, to life changing and permanent injury / disfigurement.

I have posted links to the stats before. Even if we are only talking
about 20K serious injuries, that is ample justification for spending a
couple of hundred quid on your home for your family's protection in my
view.

If we apply your logic, there are only 10s of K serious car accident
injuries a year, so why waste money on seatbelts or MoT tests?

Last time they
wanted to admit me all I needed was tea & aspirin.


--
Cheers,

John.

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