Help; Consumer Unit set up

pencilpusher · Jul 15, 2011

Hi all

I am failry new at this and am studying for my 2391 which is to be taken shortly. I like to run through different design calcs etc to get this well and truly in my head. However, a practcial scenario has come up and I am not quite sure of something. Thinking through a consumer unit change with 2 RCD's where 2 non RCD ways are also required. Both non protected circuits positioned next to main switch. I assume there would be two live bus bars in all but not sure how many neutral bars would be needed. I am thinking just two but can someone help to explain this please.

Many thanks

PP

Deleted member 26818 · Jul 15, 2011

There will be individual L & N bars for the main switch, and for each of the RCDs. Three of each.
One earth bar for all, or if a high integrity board, perhaps two earth bars linked together.

pencilpusher · Jul 15, 2011

spinlondon said:
There will be individual L & N bars for the main switch, and for each of the RCDs. Three of each.
One earth bar for all, or if a high integrity board, perhaps two earth bars linked together.

Thank you. I presume I would need to adapt the bus bars etc and add extra tails to each bar?

PP

Deleted member 26818 · Jul 15, 2011

Usually the tails go into the top of the main switch, then the first line busbar and another tail comes out of the bottom.
This tail then goes to the top of the first RCD, and loops over to the top of the second RCD. Each RCD then has it's own line busbar.
The neutral comes out of the bottom of the main switch and connects to the first neutral bar, then two neutral tails then go from this bar to the top of each RCD. This neutral bar is also used for any MCBs on the main switch.
A neutral tail is then taken from the bottom of each RCD to separate neutral bars, and the neutrals for each MCB on the RCDs are then taken to the respective neutral bars.
The earth bar will often have enough terminations to cove both the main switch and the RCDs, so when terminating the CPCs, I will leave a gap of two terminations wherever the ways are taken up by an RCD.