Consumer Unit - Dual RCD Wiring from Isolator

[TonyJr]

Untitled

• TonyJr
• 26 Jun 2008
• 2

Hello,

I have been putting together the new consumer unit for my house to make sure it's all OK before I fit it in. With the new regulations, I am going to be installing a Dual RCD CU. This consumer unit has two separate neutral wiring blocks, the same as a normal split way CU. This is where I have got a bit stuck. Do the two RCDs require their own neutral wiring block apart from each other (as i have wired in the pic attached), or can they both be on the same one... OR shall I stick the connecting U copper bar back in between them? There are going to be no RCD unprotected devices in here.

The reason I am stuck is that I don't know if one RCD will interfere with the other on the Neutral if one was to trip. Is it OK for them both to share a common Neutral?

Note the wiring isn't finished in the picture yet - I have connected the live from the isolator to the inputs of each RDC and the Neutral outputs of each RCD to an individual Neutral wiring block.

Thaks in advance for your help and advice!

Cheers,

Tony

 

[plugwash]

The neutrals out from the two RCDs must be kept seperate.

 

[TonyJr]

The neutrals out from the two RCDs must be kept seperate.

Thank you plugwash

 

[Pensdown]

Judging by your post you seem a bit confused so just to add, you will need to cut the copper bus bar.

The first piece needs to be 8 prongs long and the second piece needs to be 4 prongs long.

The first piece goes in the live out on the bottom of the 1st RCD and the 7 MCB's to the left.

The second piece goes in the live out of the bottom of the second RCD and the 3 MCB's to the left.

 

[TonyJr]

Judging by your post you seem a bit confused so just to add, you will need to cut the copper bus bar.

The first piece needs to be 8 prongs long and the second piece needs to be 4 prongs long.

The first piece goes in the live out on the bottom of the 1st RCD and the 7 MCB's to the left.

The second piece goes in the live out of the bottom of the second RCD and the 3 MCB's to the left.

Thanks Pensdown for the heads up. I think I forgot to take it out before doing the photo. I better not do that when I am installing it!

 

[securespark]

Just to eliminate any confusion, he means the piece underneath the mcb's in your picture.

 

[Spark123]

I take it you know that replacing a consumer unit is notifiable to your LABC under part P of the building regulations? Do you know how to do the required testing to ensure all connected circuits are safe, recording the results on the correct forms?

 

[oharaf]

It might be the camera angle but the unit already appears to be smiling along the top edge!!!

 

[Chri5]

I'm worried, are you qualified- just that the question is so basic I find it hard to fathom why a person with qualification would ask.

 

[Spark123]

I was thinking along the same lines

 

[Fuseblower]

I notice that the Neutral links from the Incomer main switch load side to the two RCD Neutral supply terminals are also missing.
An other oversight I presume?

 

[bongos]

Also I think the lighting/ring final circuits be mixed between the two rcd's - to avoid you losing all lighting together if that side develops a fault.

Upstairs lights on one rcd with downstairs rfc's and downstairs lighting with upstairs rfc's.

 

[Taylortwocities]

Your basic problem is that the board you have is not an MK 17th edition board. its a 16th edition board.

In the 17ED boards there are three neutral busbars. One for the supply to the RCDs (and high integrity RCBOs) , and two longer ones for the two neutrals from the RCDs.

Here's a pic

I do share the others concern about your ability to do this though....

 

[GaryMo]

Your basic problem is that the board you have is not an MK 17th edition board. its a 16th edition board.

Could it not simply be a twin RCD board without non RCD protected ways?
Not all so called '17th edition' boards (got I hate that!) have unprotected ways.
What makes you think it's a '16th edition board'?

http://www.tlc-direct.co.uk/Main_Index/Consumer_Units_Index/MK_17_Consumer_Units/index.html

 

[Cremeegg]

I'm all for giving people help but this is one of those potentially dangerous posts where we shouldn't.

This is fundamental stuff. How is this guy ever going to connect it up - by working live no doubt. Then presumably as he can't even work out how to design a CU there wont be any testing other than a functional test. Not a meter in sight.

Hope he's well insured - actually I don't because its people like him that put our premiums up.