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I came across these old PDL devices that I suspect are MCBs. Can anyone provide any information on them including what range they are from, are they MCBs and what fault currents they are rated for etc? Thanks in advance for any help!

Seen heaps of them in late 70's early 80's house builds, don't know any details other than sometimes when they tripped they wouldn't reset, a well placed tap of the handle end of a screwdriver usually fixed the problem.

I believe that - like "Lupus" mcbs and some others - they have only a thermal trip and no magnetic trip.
However being mcbs; under rules of the time they were classed as 'close protection'.
The effect of that was - and remains - they they were / are allowed more than 2 sockets on the circuit, compared with max 2 for "coarse protection" SERFs.
'Close protection' (mcb / HRC) also increased the CCC for any given size of cable; though generally offset by an equivalent de-rating for BTI.

For today's world, eg when extending an existing circuit, generally treat them as C-curve.
For non-RCD sockets they may not actually operate within 0.4 sec as required for fault protection; but fitting an RCD will solve that problem

Not sure of FC rating, but Lupus were / are 3 KA, and I would expect these to be no less;
So likely to be OK for wherever they are

Hi there guys,
These are almost similar to the old "Quicklag" breakers that used to be fitted in the older Gael switchboards.
I had to remove one of them elderly units last week as the fuse-switch unit at the bottom had failed destructively at 5 am.
I'm surprised that there are any of these still around, we fitted them when I started my apprenticeship around 30 years ago, most had got torn out due to the switch-fuse issue over the years.

Cheers,
Mike T.