A recent electrical inspection /test of an industrial premises owned by my parents says:-
Crabtree MCbs BS3871 cat M3. Have no type number, recommend replacing
does not comply with BS7671...
My question is.. are they obsolete???
Pah!
Obsolescent, perhaps - their catalogue says this:
"The tried and trusted Magnetic/Hydraulic mechanism of the C50 remains as before, albeit in a slightly reduced range. The Enclosure system for the C50 MCBs however, is undergoing some dramatic change. The old enclosure system with separate Enclosure/ Interior and ?dished front plates is being phased out. Current stocks, once exhausted, will not be replaced. The New C50 Enclosure System will utilise a modern style enclosure with doors fitted as standard, but will only be available in assembled format with 100A or 200A Incoming Isolators prefitted."
Download the industrial circuit protection catalogue section from here:
So basically the answer is yes the C50 is obselete and the breakers are expensive to get anyway.
The breakers are still listed in the current manufacturer's catalogue and are available from wholesalers and several web sites. They're now made to BS EN 60898 (Type C, M4.5) not the old BS 3871. I wouldn't call that obsolete. Nor do I see any particular need to replace them in an older installation which was designed and wired before BS 7671 even existed (during 14th or 15th Edition eras, most probably) - provided there's no evidence of damage or deterioration of course.
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