Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 8 replies
  • Subscribers 37 subscribers
  • Views 1372 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Demand and Diversity Assessment

Philip Conlan

I have come across an old commercial site with several boards/sub-boards non of which have been considered for selectivity with MCBs or RCDs.

When looking at the demand and diversity from 1 supply nothing seems to add up, or either I'm looking at this all wrong.

DB2 I would assume that the demand after diversity is too great for 1-the 6mm cable CCC and 2-the 32A MCB supply from DB1 is underrated.

if anyone could provide some clarity on this installation that would be helpful.

Currently, I'm working my way through the IET design guide and trying to get a better understanding.

Thanks

Parents
  • 0

    It looks a poorly designed installation, and should not be designed or installed like that these days.  A short circuit on the 32 amp socket outlet circuit might trip two or more MCBs, thereby interrupting supply to other loads. 

    The single RCD also protects a possibly excessive number of final circuits.

    In the case of an existing installation, if it works reliably without unduly frequent trips, then I would be inclined to accept it.

Reply
  • 0

    It looks a poorly designed installation, and should not be designed or installed like that these days.  A short circuit on the 32 amp socket outlet circuit might trip two or more MCBs, thereby interrupting supply to other loads. 

    The single RCD also protects a possibly excessive number of final circuits.

    In the case of an existing installation, if it works reliably without unduly frequent trips, then I would be inclined to accept it.

Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines