11:24 Jul 18, 2010 

After reading the ST again (pouvant inclure entre autres) - author seems to review the possibilities - one of them might be a backup power source - mentioned simply as "réserve". So the CB is not a "backup" one per se - it if for connecting the "backup power source". My 5 cents.

11:12 Jul 18, 2010 

Here, we are not talking about spare as in spare parts (supplied separately, stored in a cupboard somewhere...) — this would be a case of installing CBs that are not actually assigned at the outset.

This sort of thing often happens with, for example, modular dis. board systems, where not all the 'spaces' are needed, but may be poplated anyway, to allow for future expansion / changes.

10:48 Jul 18, 2010 

It would appear to me that either term could be relevant in this case - it is not, in my view, clear from the source text which of these terms would be the most correct translation. (Google shows 21,600 hits for "backup CB" and 4,670 for "secondary disconnect". (It would appear to me that a s.d. is one application for a backup CB).

On the other hand, 'spare CB' does not immediately strike me as being a relevant term in the given context; why would CB's be singled out in connection with spares - surely there would be many other spare parts, which would also be relevant in such a system.

22:46 Jul 17, 2010 

Is as good as mine. I wish authors were more accurate :-)

22:40 Jul 17, 2010 

Or maybe not just a slot, but a unit installed for future use. Hard to say without knowing what it is. Some alternator/mains interconnects are overwhelmingly complex, especially the fault-tolerant ones, and I can't rule out a "backup CB" in that kind of thing.

22:07 Jul 17, 2010 

I can hardly justify a "backup" CB - more like "spare" slot in the switchgear - for use in the future.