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Old July 6th 11, 11:30 PM posted to uk.d-i-y
Andy Dingley Andy Dingley is offline
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First recorded activity by DIYBanter: Jul 2006
Posts: 5,175
Default Earthing question - plastic in metal?

Suppose a piece of kit is Class II double insulated and doesn't need
an earth wire (proper factory stuff with magic stickers & everything).

It's now placed inside a big tin can.

This tin can is placed temporarily in an environment that's full of
high power electrics, ad hoc connections, extreme hazard for shock or
falls from a height. The culture here (on paper at least) is that
everything has to be carefully earthed and PAT tested before use,
especially if it's foreign kit coming in from outside.

If you're wondering, it's stage lighting gear.

What's the situation here, both practically and legislatively? An
argument can be made that a class II device that is safe without an
earth doesn't (or does it?) become unsafe if it's inside a conductive
metal outer housing. Despite this though, any sensible spark with
responsibility for incoming kit will presumably see a metal housing
and want to see an earth connection to it - they have neither time nor
credible ability to open it up and demonstrate that the insides are
safe without?

Thanks for any comments.