Is what "is accepted" not that such circuits should, ideally, not be fed from RCDs which are protecting other circuits? Do you also see a problem if, as was suggested, it is fed from an RCBO or dedicated RCD (theoretically removing the need for further RCD protection downstream, unless one wants redundancy)?
I suppose, but that would be foolish for two workshops.
That would be a problem in itself.
Of course there are but as that is one then take advantage of it.
I don't really understand either of those responses. Could you perhaps expand/clarify? thanks.
I think that would be foolish to do because there are better ways, and could be a problem in the usage of that circuit.
Because a fault in one workshop would take out the supply to the other? Maybe I misunderstood, but I got te impression that both of these workshops were just for the OP's personal use (and he may well largely stop using the small one once he has built the larger one), in which case he couldn't be in both at once.
Do you think it foolish just because of my comment about redundancy? If so, I only mentioned that as being the only reason for ('unnecessarily') having an RCD in the outhouses if the circuit already had upstream RCD protection.
Yes, I did think of that as an option. In fact, that's equivalent to what I have in my (TT) house, with (very long) distribution cables (not SWA) protected by 100mA TD RCDs and 30mA RCD protection on all the final circuits fed by that cable.
Whilst I do not disagree that what you suggest could conceivably happen (although extremely rarely), I'm not sure that it is necessarily anything to worry about - what do you perceive as being the problem with "localised heating at the fault location" in an underground cable? (By the time the scenario you envisage had arisen, the cable would have to be replaced, or at least repaired). In any event, you are essentially talking about an 'overload current' and, provided only that the MCB was appropriately rated for the size of the cable, it would, by definition, operate before the cable was at risk of thermal damage (which implies not enough heating to damage anything else, either).
As I said, by the time the scenario you envisaged had arisen, at least part of the cable would already have 'catastrophically failed' - and, as I also said, the MCB, if appropriately rated would protect the cable in general from any harmful effects of the current through the fault (which, as I said, is, in magnitude, equivalent to an 'overload' current).
Much as we considered a month ago.
Yes they will - I've already run the new SWA but as you can guess build is slow and #lockdown isn't helping
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