Crabtree C50 breakers.

monkee · Aug 16, 2011

HI all,

what BS number is the crabtree c50, if there is one?

are thay acceptable as PIR reports, say a sub main 16 amp feeding a caravan ( fixed static ) with an old ELCB?

any thoughts

regards P.:crazy:

Electro-tech · Aug 16, 2011

BS 3871. Is the ELCB a old Chilton voltage operated?

MarkieSparkie · Aug 16, 2011

Hi monkee, The Crabtree C50 MCB is BS EN 60898, NOT BS 3871 as stated by Electro-tech. If your sub-main cable is only rated 16A, then a 50A MCB is inappropriate and needs to be de-rated, Code 1, requires urgent attention, on the PIR.
Check whether a C type is appropriate for the application, they are usually specified when there is fluorescent lighting, small motors etc that may produce switching surges that would operate a B type MCB.
Voltage operated ELCBs do not comply with BS 7671 and should be Code 1, requires urgent attention (replaced by RCD/RCBO) on your PIR.

Simlec · Aug 16, 2011

“Crabtree C50” I think he means the old ones that are black and the size of an old house LOL. I'm not 100% but are they BS 3871 as said.

IQ Electrical · Aug 16, 2011

If this is the C50 range of miniature circuit breakers then yes, they are BS 3871, normally with a short circuit capacity of between 3 and 10 kA.

They are acceptable if the other design parameters are met.

The ELCB was the name given to the early residual current devices and may be acceptable however, if it is a VOELCB (usually has a yellow test button and a terminal marked 'F' or 'Frame') then it should be replaced with a suitably sized RCD.