Do the regs allow two DBs to be connected in parallel protected by only one mcb. i.e. a cable feeds DB1 then another cable goes from DB1 to DB2 but connected directly to the feed for DB1.
I've looked in the regs but cant seem to find anything that prohibits it.
Our inspectors don't allow it, we must run from separate MCBs or Henley blocks of a suitable rating.
I suspect it's the overcurrent in the terminals you are using for paralleling
An instance we had was running a DB for emergency lighting paralled into the lighting DB - not allowed
I think that you would have to install as two radials from the one breaker unless you are running a separate heavier earth bonding to the two DB's don't you ? Or are you allowed to use the armour of SWA Cable as your earth link ? As you say Pablo, the book don't make any specific mention of such an installation.
"Pablo" wrote | Do the regs allow two DBs to be connected in parallel protected | by only one mcb. | i.e. a cable feeds DB1 then another cable goes from DB1 to DB2 | but connected directly to the feed for DB1. | I've looked in the regs but cant seem to find anything that prohibits it.
It's a very common arrangement both domestically (where the supply from the meter is split by a 'henley block' to feed to CUs and industrially - quite often DBs will be supplied on a ring main.
Obviously both short-circuit and overload protection have to be adequate, and I think you'd have problems looping the cable in and out of your DB1 unless its terminals are designed physically (and rated electrically) to accommodate it.
Owain
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