On 19/05/10 00:58, Dave Plowman (News) wrote:
In ,
Dave wrote:
Just to be clear on this point, you absolutely *must* megger each piece
of pyro/micc after you have potted it but before it is terminated. It is
*not* suitable for DIY if you don't have access to a 500V insulation
tester.

With respect, ********. I'm assuming you're using new cable - not
something stored in the rain for years. There simply is no need in
practice if you work carefully.

BTW, what do you consider the difference between 'potting' and
'terminated'?


No, I agree with Dave O. PVC if new and visibly undamaged can reasonably
be assumed to have good insulation.

You cannot assume that, in particular, a piece of pyro bought from ebay,
or an offcut from the wholesaler, hasn't been subjected to damp.

Also, as a DIYer, I wouldn't feel happy unless I could megger the thing
3 months down the line. Potting is possible to get wrong, letting in
moisture later.

Noone said you couldn't DIY a tester for this purpose - it is after all
only a 500V DC test. Given pyro can cope with 1000V tests, the simplest
(and slightly dangerous, but not if you're careful) tester would be a
mains driven voltage doubler (couple of diodes and capacitors), limiting
resistor and an micro-ammeter.

Cheers

Tim

--
Tim Watts

Hung parliament? Rather have a hanged parliament.