In message ,
"Owain" wrote:

"Martin Angove" wrote
| (jim_in_sussex) wrote:
| you need an RCD - even then that takes 0.4s -
| Leaving aside the merits or otherwise of RCD protecting
| and/or bonding everything in sight, I thought the specification
| for the "life saving" 30mA trip RCD was 40ms, not 400ms

The requirement is for a 0.4s disconnection time (through EEBADS) on socket
circuits, whether that is achieved by fuse, MCB or RCD, and is in the wiring
regs. The BS for the RCD is a different matter.


Yes, I realise that the requirement for the circuit is 0.4s (or 5s
depending on the circuit), but Jim wrote something which implied to me
that he thought that an RCD took 0.4s too; the bit which went:

a fuse/mcb won't trip on the current/voltage that gives a fatal shock -
you need an RCD - even then that takes 0.4s

In testing RCDs I have to admit that even at 1x current I've only once
seen a (30mA, non-delay) RCD take longer than 40ms to trip, and that was
because it was mechanically knackered. At 5x current most seem to manage
around 10ms. Again though, I realise that this is a feature of the RCD,
not a specific requirement of the BS disconnection times.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
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