On 8 Nov, 09:42, PeterC wrote:
On Sat, 7 Nov 2009 13:30:16 -0800 (PST), robgraham wrote:
It was the lathes that concerned me most as the end of each session
(twice a day often) the plugs are removed. *I don't know what regime
is in place to inspect the plugs, but such frequent movement could
lead to disconnection of the any of the leads inside the plug, with
the corresponding hazard.

We had this at work - the sockets (MK metal-clad) occasionally failed by
falling apart internally sometimes with bang and smoke. Checking sockets
mechanically every few years might be necessary.
Another consideration is the plug: the sort that has a medial split can
fail in a dangerous way, as the operator's fingers can contact the
conductive parts if the sccrew fails, so the fully capped type is better
(the ones that need a bit cutting out to get on after wiring :-) *).
--
Peter.

You need to replace the '13 Amp' BS1363 plugs & sockets with
industrial connectors, such as the 'Commando' type, made by many
manufacturers to BS EN 60309-2 (formerly BS 4343). These do vary a bit
in quality, but these two manufacturers seem to offer a quality
product, available in metalclad versions as well as the more common
plastic:

http://www.lewden.net/

http://www.a-belco.co.uk/Connectors/CEEGO.html

or for real class there's the 'Reyrolle' BS196 connectors:

http://www.a-belco.co.uk/Connectors/Easigo.html

as used by the former nationalised industries, BR, CEGB, LT etc.

BS1363 connectors were only really intended for domestic purposes, to
provide sockets which could be mass-produced cheaply for the post-WW2
rebuilding programme, they do not stand up to industrial use. Even
BS546 round-pin connectors are better.

Lewden do make a superior weatherproof version of the above types
though, both the plugs and the sockets, look up the 'Weathertight'
range on their website.