Non standard connections in CU

WayneL · Nov 26, 2009

Hi All,

Recently did a PIR on my brother-in-laws house (practising for my 2391 next week)

Most things were fine and everything tested okay - the only thing that caught my attention was this:-
(opinions appreciated)

It was a Square D split board - half circuits on RCD and half not.

The MCBs were the type with the prongs in the top (incomers) which click in and connect to the relative busbar. Outgoing circuits out the bottom of the breaker.

All were Square D MCBs exept one - a 32A (from wickes) on the non-rcd side feeding a shower.

This was a standard MCB with it's incommer at the bottom and no prongs anywhere.

This is where it gets even more strange.......

The feed for this breaker is taken from the incommer of a breaker on the RCD side of the board via a brown 6mm single core cable (about 8 inches long fastened into the top of the breaker along with the prong)

This then terminates in the incomming side of the 'Wickes' breaker - obvious intention was to provide RCD protection for the shower circuit with no spare ways available on the RCD side of the board.

The circuit neutral was connected to the RCD side neutral bar.

Like I said everything tested okay so-

1/ Although it's not recommended to mix and match MCBs is it against the regs ??? and would you code it???
(bearing in mind that this MCB has it's incommer at the bottom and it's outgoing termination at the top - the oppositeway round to the SQ D ones!!)

2/ I know that the wiring of this MCB would get a 'code 5 - bad practise' lol But does it actually contravene any regulations??? I've been looking and can't find anything specific about it.

Thanks in advance for your answers

Wayne

Mr Mark Sparks · Nov 26, 2009

id be more bothered about the connection on the sq d breaker as long as its sound
its ok to mix mcbs but not ideal the wickes breaker is prob made by a well known company anyway
i would sat reqiures improvements

pennywise · Nov 26, 2009

Contravenes the manufactures instructions and recommendation would have thought. so are you saying that the 6mm single core cable it jammed into the bus bar along with the prongs of the square D breaker might have read wrong.

Mr Mark Sparks · Nov 26, 2009

pennywise said:
Contravenes the manufactures instructions and recommendation would have thought. so are you saying that the 6mm single core cable it jammed into the bus bar along with the prongs of the square D breaker might have read wrong.

thats what worried me

WayneL · Nov 26, 2009

Thanks for the replies.

I think it's 'Clipsal' that Wickes sell and I suppose it wouldn't be so bad if it was a bottom busbar mounted board (so they were actually the same type of MCB) but those SQ D breakers with the prongs are completely different.

Then there's the wiring of it from the other side of the board??

No, Pennywise, the prongs terminate into the top of the breaker and are tightened with a screw (much like your cable does on normal MCBs) you can actually take the prongs out if you don't require them - the 6mm is screwed in with it.

Like I said this PIR was only done as pratice for me, and there isn't anything actually dangerous about the installation, but what would you do if you came across this in the real world??

Cheers,

Wayne

Guest123 · Nov 26, 2009

Sounds a bit phil the badger does that.

I have seen it in the past, when you take the top off of one of those type SqD breakers they are like a standard MCB, with a normal screw connection that the bus prong is clamped into.

Although bad practice and I would say code 2, the effectiveness of the connection is probably sound.

Needs to be corrected though.

pennywise · Nov 26, 2009

That what I thought have been looking trying to find the square D breaker design, If i remember rightly there are little plastic inserts which cover that terminal screw, correct me if I'm wrong .