Re: LF: mains wires

[Scott Tilley <sthed475@telus.net>]

On 10/10/2011 1:19 AM, mal hamilton wrote:

Tnx Scott and others for the info. Your system is more complicated because of the 117 v and 230v dual supply required.

In the UK there is more conformity to wiring and the plugs are non reversible into the socket, whereas your 2 blade plug goes in either way round and no Earth.  In EU their 2 pin plug is also reversible but does have an earth.

There is a conformity here too.  Just different!

Ours is non-reversible as well.  The neutral blade on a reinforced insulation class plug set is wider than the hot so you can't switch them around.

There are two main ways to achieve safety from electric shock in equipment design:

1) Supply the equipment with a ground conductor and bond it to all conducting surfaces.  I.e. a three wire cordset...

2) Reinforce the insulation such that it is unlikely to degrade and ensure that is used throughout the appliance.  Most often this is used with non-conducting enclosures etc.  This allows the use of a 2 wire cordset.  SPT-2 cord is the smallest allowed for most appliances.  SPT-1 is only now allowed on lighting products there the wire is pulled into a chain or otherwise protected...

When using NA 117v  equipment in the UK it is probably best to use a step down ISOLATION  transformer, and  rewire the 230v equipment  mains cord to be compatible with all the other shack eqjuipment.

Yes it can be a trial to get equipment from around the world to co-operate.  It's even worse in industry where all of the complexities and differences of the grids cause alot of headaches...

73 Scott