Exactly. Maybe I misunderstood, and didn't realise that you were talking about a 'workplace', since ...
Sub Consumer Unit
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At the sub-CU end, you mean? If so, then the simplest thing would probably be to have a main switch in it, and connect in the usual way. Although there is a (BS7671) 'requirement' for there to be a single means of isolating the entire installation (which would be the main switch in the 'main' CU), there's nothing to say that one cannot also have a second switch downstream of it (and, indeed, as I said before, that's what I would personally want).
What BS7671 does not want is two CUs, each with their own main switches, fed (presumably via a Henley block) from the meter tails - since there would then be no 'single point of isolation' for the installation.
The Proteus stacked individual CUs only has one mainswitch incomer, for obvious reasons. It is OK if the tails from the master CU go into an RCD, or jumped to second RCD in the sub CU. Fine, sorted. But what if both CUs are on RCBOs? I can only think of drilling into a bus bar as the solution. I do not know how Proteus, and others, get around this, as stacked CU are rare.
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How do you think two RCCBs in one CU are connected? Plus there might be a couple of RCBOs as well.
The N presumably just goes to a neutral bar.
As for the L, I would think you could just do the same as I suggested for the other end (using a master switch terminal) - i.e. put the L (together with the L bus bar) into the L terminal of one of the RCBOs.
Without getting sucked into the deep technicalities, you have an existing CU that is full & you need extra circuits?
Can you fit RCBOs into the existing CU (assuming it is a dual RCD type that would win you 4 circuits)
Pic of the space would be useful, if there's room for one of those stacked CUs there's probably room for a conventional creative solution
Can you fit RCBOs into the existing CU (assuming it is a dual RCD type that would win you 4 circuits)
Pic of the space would be useful, if there's room for one of those stacked CUs there's probably room for a conventional creative solution
It seemed as if he was thinking of EAWR, but when I asked him what relevance EAWR had to what we are talking about, he (correctly) replied "Nothing" - so, as they say, 'go figure'
Kind Regards, John
Indeed - a 'wider' CU installed 'on it's side' might be one of those creative approaches!
Kind Regards, John
Double RCD in a CU have two cables into one purpose made lug (comes as a kit with the CU), that is inserted into the RCD terminal. They do not have two cables rammed into the terminal. OK two cables can be soldered together. But the insulation melts, looking bad. So some sort of crimped lugs are needed.
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You are saying put the L tail cable and the bus bar lug onto one of the RCBO's terminals Fine.
Yep, just as is done with the L load terminal of a main switch in a dual-RCD CU.
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