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16A sockets in domestic installation

I'm intending to use a small CNC at home. It needs a 16A single phase supply and preferably I'd just connect via an interlocked EN 60309 commando socket, but that would be a departure from 553.1.201 because commando sockets aren't shuttered.

Ironically I would be okay installing a European Schuko on a 16A radial - because they are shuttered but clearly not particularly robust for a workshop and not polarised either. Maybe get an IEC 60906-1 from South Africa.

Of course I can risk assess a departure from 553.1.201 given that interlocking offers a greater level of safety than shutters. 

I could use a 15A BS 546 but these days protective devices are harmonised at 6, 10, 16A etc. And BS 546 / BS 1363 haven't kept up, so a 15A wouldn't have sufficient protection and in any case i think an interlocked commando offers a greater level of protection.

I presume many electicians just put commandos in people's garages without even considering that they're departing from BS 7671.

I get the impression 553.1.201 is a old provision which when read today has unintended consequences. It is of course a national departure from HD 60664.

What are people's thoughts on using commando sockets in a dwelling? In terms of the departure risk assessment, are there circumstances in which an interlocked socket may offer less safety than a shuttered socket? 

  • A CNC has drives to precision control the motors so you've just got to go of the nameplate. 

    It says 15.4A. In reality I'm probably never going to draw that but the nameplate is all you can go of.

  • Turned pins into a metal hole with a transition fit gives a very reliable contact, and if it's past it's best it's got enough copper to draw away heat from hot contact spots.

    Not all plug pins are solid brass ... I agree that most industrial plugs and appliance inlets to BS EN IEC 60309 series tend to be ... but provided the temperature rise, durability, etc., tests of the standard are met, I don't believe there would be anything to prevent a product with a hollow, or plastic filled hollow, contact pin (give or take getting patent licenses where necessary, as with other design features).