Discuss Splitting an Sigle RCD board in the Electrical Forum area at ElectriciansForums.net

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N

nrg

Hi All

I have a customer who would like his part RCD protected board made a full RCD board by adding another RCD unit. When looking at the board there are only 2 neutral bars. He doesn't want me to replace the board as it was only fitted in 2007. Any advice if it is possible? I can think of a way to do it but not sure if it would comply with the regs
 

topquark

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As above, just swap some of the MCB's for RCBO's (with a bit of shuffling/new busbars). Only need the two neutral bars then.
 
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spark 68

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You only need two Neutral bars for a dual RCD CU anyway, you can buy what is known as split load kits, but this depends on make and model of CU, and assumes you have enough space to fit the additional RCD in, (the RCD commonly takes up 2 ways).

RCBO's are easier still to fit
 
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OP
N

nrg

Thanks, the board is pretty crammed! How is it done with 2 bars? Don't you need 2 bars for the RCD protected sides? And another for the main neutral?
 

topquark

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Main incommer -> first neutral bar, first neutral bar -> RCD supply side, RCD load side -> second neutral bar. MCB's/RCBO's on first neutral bar, RCD Protected MCB's on second.

Edit: This is for 1 RCD and RCBO's/MCB's NOT for 2 RCD's
 
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telectrix

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nope. you need 1 neutral bar for each RCD. you only need a 3rd N bar in a hi-integrity board. i.e where you have 2 RCDs and 1 or 2 non-RCD ways
 

Murdoch

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What make and size of CU is it?
 

spark 68

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Thanks, the board is pretty crammed! How is it done with 2 bars? Don't you need 2 bars for the RCD protected sides? And another for the main neutral?
It is done by a twin Neutral cable that fits the out going side of the mains switch and feeds each seperate RCD.

The live side is similar.

Then a seperate N bar for each out going sides respective RCD
 
OP
N

nrg

I have room for the RCD next to the main switch, if it's split with 2 RCDs 50 50 I only need 2 neutrals? So the main neutral and RCD 1(out) on one, and RCD2 on the other? Wouldn't that mean rcd1 and 2 are connected?
 

spark 68

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I have room for the RCD next to the main switch, if it's split with 2 RCDs 50 50 I only need 2 neutrals? So the main neutral and RCD 1(out) on one, and RCD2 on the other? Wouldn't that mean rcd1 and 2 are connected?
Only on the incoming side, they are seperate from then on .
 
OP
N

nrg

What a dumb ass! Thanks spark 68 just 2 neutrals coming from the main switch out to each RCD? Mental block! Thanks again
 

sparks1973

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just go and get a BG board from screwfix....50 odd quid...i`v fited a few of these now...and i think their OK....plenty of room in em n all.....
 

spark 68

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You also need two seperate cables from each outgoing side to the respective N bar, the live outgoing side is taken care of by seperate busbars for the MCB's
 
OP
N

nrg

Yes I got a split kit which will work fine. I can't believe I made it so complicated! I've been pondering this for two days! I need to drink more!
 

sparks1973

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thing is...if were having to explain this to someone.....i would be questioning their competance to undertake this work.....
 

telectrix

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just go and get a BG board from screwfix....50 odd quid...i`v fited a few of these now...and i think their OK....plenty of room in em n all.....
and that's a hi-integrity board as well. all for £50 ( b&q ). it will cost you £25-£30 for an RCD and a kit of splitter tails.
 
OP
N

nrg

I think you mean "if we are" not were! All the boards I fit from scratch are now high integrity! And had a mental block at 5pm
on Friday! Chill 1973
 
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spark 68

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One other point,

You will need the incoming feeds (L and N incoming) for the RCD's at the same side, this is usually the top side, where the busbars fit in the bottom, and your N cables to the N bars (outgoing side) from the same side as the busbars.
If that makes sense.
 
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