Consumer Unit Change

[Nickj]

Hi All,

I am tomorrow going to be changing a consumer unit ahead of my Elecsa assessment next week.

Just wanted to check that I'm not missing anything with regards to amendment 3.

I'm going to be using a BG consumer unit supplied with RCBOs.

It has a cut out at back for cable entry and so I am going to pass all cables through that using a grommet strip around the metal edges. Do I need to seal the entry hole? I believe not however I have heard arguments that it needs to be sealed. Passing all cables through the rear entry may require de-rating cables due to grouping however the cables enter the current board (3036's) through the rear. Can i therefore assume ratings are fine?

I am going to attach the consumer unit to the wall using dewalt wall dogs which require no anchor in wall meaning I don't have to worry about plastic wall plugs falling out in the event of a fire.


If the cables are too short (I sincerely hope they won't be) I'll use an adaptable box above the board to mount a din rail to extend wiring. Does this adaptable box need to be non-combustible too? (associated switch gear covers this possibly?)

Thanks in advance

Nick

 

[Pat H]

Trouble is then you need to bond them. Daz. (popcorn ready).

Ok I'll bite... As long as the metal enclosure has exposed metal at the rear of that blanks connection won't it be bonded via that?
And if it does need a bonding cable will 10mm be enough

 

[DPG]

The metal to metal contact between enclosure and blank would be inadequate . Daz

 

[Pat H]

The metal to metal contact between enclosure and blank would be inadequate . Daz

A rivet maybe?

 

[DPG]

Brass nut and bolt with flylead to earth bar. Daz

 

[Wilko]

I'm concerned about introducing another conducting surface - it can't be good can it? I've been filling spaces with mcb or a plastic dummy.

 

[Pat H]

Brass nut and bolt with flylead to earth bar. Daz

10mm or go the whole hog and make it 16mm? after all it could contact a pretty serious bus bar...

 

[Nickj]

Hi all,

I've fitted the mk blank mcbs. They look ok (not as neat as the plastic blanks in my humble opinion).

Just to clarify one point.

They fit neatly but I would say just about fall short of ip4x. I am correct in thinking for the mcbs and main switch I only need ip2x? (I'm way above ip2x, close to ip4x).

Thanks all for your help, tomorrow is the day and so I'm pretty much out of time

 

[Pat H]

Only the top is ip2x the rest is ip4x

 

[Nickj]

Sorry pat confused by your response?

 

[DPG]

Wrong way around maybe. Daz

 

[Pat H]

Sorry yes the other way round.
Only the top is ip4x the rest is ip2x
My bad

 

[westward10]

I use the Wylex metal blanks - they can only be fitted before the cover is fitted.
These are the blanks I was referring to didn't realise Wylex now do them in metal, normally fill spares with mcbs. So this begs the question are plastic blanks still acceptable with the metal enclosure.

 

[Nickj]

Thanks all, I'll post tomorrow to let you know how it goes.

Plastic blank mcbs meet all requirements. Let's not forget the mcbs themselves are plastic.

The plastic blanks I can see being an issue as they can be removed without the use of a tool to varying degrees, some are great but really the ones I had could be removed with some wrangling.

The plastic blank mcbs cannot be removed without a tool amd therefore are entirely up to the job.

The reason I didn't use the metal ones are for the reasons discussed above. The board is painted and so they wouldn't have been earthed.

Chances of a cable coming into contact with them is slim but still a chance I guess.

Feeling absolutely fine with the blank mcbs

 

[Pat H]

Don't sweat it. Worst case he makes a comment and you discuss it.

 

[DPG]

You're worrying far too much about these blanks! Daz