On 20/05/10 00:15, Dave Plowman (News) wrote:
In ,
Tim wrote:
On 19/05/10 11:22, Dave Plowman (News) wrote:
Water damaged pyro is pretty obvious to the experienced - the MI isn't
a powder anymore. It also progresses through the cable pretty slowly -
so normal stripping will sort most.
And an ordinary decent DVM will show clearly if you have this
condition.
As regards water getting in later - take care making the termination
and it won't. Unless the cable gets badly damaged - which is a
different matter.
You may ask why test any new installation?
I'd ask how many times faults are found.
In my personal experience, once in the last 2 years. Broken neutral in a
ring. Would never have noticed if I hadn't followed the standard testing
regime.
So, categorically, I say, without any hestistation, new work *should* be
tested. Perhaps *inside* a house with all new components and T+E, one
could skip the IR test (I've never seen that anything than offscale),
but there, continuity and RCD tests are very wise.
You may argue that in the case above, a simple multimeter would have
been good enough for the end-end ring test that would indicate a broken
conductor. Yes it would. Even the diagnostic search was done with a
binary search rather than trying to be clever with conductor resistances.
But, what if the RCD was out of spec? That does happen and it's rather
harder to test those. Pyro, especially if it is terminated for the first
time by an inexperienced person, AFAIC *must* be tested, if if the test
is gerry rigged. Pyro has a known failure case (mositure) that is
considerably more likely to occur compared to leakage in a T+E installation.
With respect, I don't care if *you've* done thousands of pyro
terminations - that means you have a feel for what's right. Newbies
don't. I wouldn't either, so they and I ought to be testing the stuff.
And IMHO *we* (uk.d-i-y) ought to be promoting good practises
Not
saying "********" to someone who is doing so...
Cheers
Tim
--
Tim Watts
Hung parliament? Rather have a hanged parliament.