DNO removed RCD on TT system

[AdrianUK]

I can't really disagree with any of that - but would it be normal to bring in a split-phase supply as two separate cables, each with a neutral?

I have seen split phase presented like that, although it is usually labelled as such. Also, the DNO combined the neutrals after the cutout but before the meter. This looks like the installer has combined the neutrals (different type of meter tail on the consumer side). Not sure I'd be combining neutrals unless I understood the supply arrangement - they could be from different transformers

...... What are the top two bits - they look like single-phase boards to me. Might the two supply phases not be split between those three 'sub-boards', with just one of the supply phases going to the 3-phase board (with all three phases of the board paralleled), in which case there would not be a 460V issue? ... would there be anything wrong with that (provided the two phases were vaguely balanced, for the sake of the single neutral)?

The top two boards look like 'extension boxes' to me (they have no isolator) and as such are intended to be 'piggy backed' onto the bus bars of the main board. Wiring in the way you suggest would fall foul of the 'one main switch' rule.

Most of the larger fuseboard manufactures do a 'single phase' kit which does parallel all three phases but nobody seem to cater for the 'split phase' supply ..... the only real answer is two single phase boards.

 

[JohnW2]

I can't really disagree with any of that - but would it be normal to bring in a split-phase supply as two separate cables, each with a neutral?

I have seen split phase presented like that, although it is usually labelled as such.

Fair enough.

Also, the DNO combined the neutrals after the cutout but before the meter. This looks like the installer has combined the neutrals (different type of meter tail on the consumer side).Not sure I'd be combining neutrals unless I understood the supply arrangement - they could be from different transformers

Indeed - but, of course, it's possible that the installer did fully understand the supply arrangement - something that we don't

The top two boards look like 'extension boxes' to me (they have no isolator) and as such are intended to be 'piggy backed' onto the bus bars of the main board. Wiring in the way you suggest would fall foul of the 'one main switch' rule.

Fair enough. ... but now that the DNO have installed the "2P+N" isolator, couldn't that count as the 'one main switch' - or does it have to actually be on the board?

Most of the larger fuseboard manufactures do a 'single phase' kit which does parallel all three phases but nobody seem to cater for the 'split phase' supply ..... the only real answer is two single phase boards.

What (apart from the possible 460V issue) is wrong with the installer paralleling two phases (as you suggested had probably been done)? You've certainly still only got 'one main switch' then.

Kind Regards, John

 

[ban-all-sheds]

Wiring in the way you suggest would fall foul of the 'one main switch' rule.

Which rule is that?