"Jim K" wrote in message
...
Dave W

No apparent way in!

Moulded brown plastic with 3 terminals.

How come contacts welded with a 30ma rcd installed & working?

Jim K

The 30ma is the current to earth before it trips.
It probably tripped as a result of a transient ie not a "real" fault to
earth.
The actual damage was due to the short circuit & could have been 60-100a
for a few miliseconds.
A lot depends on what part of the cycle is happening at the instant the
fault occurs.