Help needed on CU Upgrade

[Aquaman]

Hello all.

I am upgrading my bungalow fuse box to a new split load CU. My circuits on the fuse box were, 1. Cooker, 2. Heat pump and sockets, 3. Immersion heater, 4. Lights.

My new CU is a split load CU, to which I decided to separate the circuits between 2 RDC's in the following way, (From right to left) Main Switch, then RCD 1 with Cooker on a 32A MCB, then Immersion on a 16A MCB, then the lights on a 6A MCB followed by 2 spare spaces.

Then I put RCD 2 with the sockets on a 32A MCB, followed by the shower pump on a 16A MCB.

I did all of the tests such as, continuity, method 1 and 2, IR.

It's a bungalow, and it appears that the sockets are not a ring, but a radial so can't do end to end tests etc.

The problem is that the first RCD trips out as soon as I energise the lighting MCB and the 2nd RCD trips out as soon as I energise the sockets circuit.

Any help would be gratefully appreciated.

 

[Plonker 3]

Sounds like a borrowed neutral. More testing needed to find it.

 

[bartkusal]

how many neutral bars you have in your new CU

 

[Plonker 3]

Also why even though you know there is no continuity on the RFCs have you put them on 32a MCBs?

 

[markc123]

If the sockets are a radial and you have them on 32a have you got them wired in 4mm?

The RCD's trip when theres a leakage to earth, i suggest you go through the test procedure again + check that you haven't got the neutrals mixed up.

- - - Updated - - -

I am officially so slow at typing today, thats the second thread in a minute that Dillb has beaten me lol.

 

[trev]

The sockets were on one MCB/fuse rated at 32/30 amps, now they're on two.....
I'm not keen on "it appears that the sockets are not on a ring" if you did your testing properly you'd have found that out for definite

 

[shocking_eg]

all sounds a bit diy to me...

 

[R G]

Get Lofty in .....

 

[Aquaman]

I have 3 neutral bars.

I initially thought the sockets would be in a ring, but the end to end tests failed so assume it's a radial as nothing proves a ring circuit.

I thought it may be a borrowed neutral and will check each neutral bar tomorrow.

Anywhere else I should check for a BN?

Thanks

 

[trev]

Get Lofty in .....

Aquaman needs someone to help him mate not an executioner

 

[lofts]

whats up with you trev

 

[R G]

Entertainment at last , begining to think the night was wasted....

 

[Des 56]

Why have you decided to load the one rcd with both radial circuits,which presumably are supplying all your sockets and on 32 amp mcb (4mm assumed) ? What is the reasons for this decision

 

[bartkusal]

It was definitely a ring some time ago, I presume the T+E is 2.5 and 1.5 in your case if protected by 30A fuse, where now then you have 2 radials each on 32A mcb’s, NOT GOOD. Makes me question, are you really should be doing this…

 

[Aquaman]

You're right Trev. Will go through it all again tomorrow.
Thanks