Is this a borrowed neutral ?

[binky]

Looking at your configuration of the new CU it seems at odds with most manufacturers instructions regarding the grouping of potentially high load RCBO's due to the cumulative thermal effects that may effect there expected operation

not seen any comments about thermal loading, but if that is the case, what a crock of horse manure!

 

[poni]

So the plan was to move all the lighting circuits and an existing 16A (15A in old money) boiler circuit

Looking at your configuration of the new CU it seems at odds with most manufacturers instructions regarding the grouping of potentially high load RCBO's due to the cumulative thermal effects that may effect there expected operation

does this matter, novice says he is only moving lighting and boiler circuits?

 

[novice]

Yes just lighting and boiler. The remaining RCBOs in the Fusebox are placeholders for if the old Wylex gets replaced completely - I've also got some blanks. I didn't see anything in the Fusebox MIs about order of rcbo in the box although I have seen plenty of electricians who like to keep the highest amp modules closest to the main switch. Grateful if someone can point me to the appropriate reg or Fusebox MI ? Everything else being equal I'm inclined to move them.

I plan now to follow the tests in my on site guide for the circuits I've moved. Then I'll torque to the settings which are helpfully labelled on this box.

Not sure if the "horseshit" comment was aimed at the wylex box, my new box or the previous comment? Either way I'm happy the new work will be to a higher standard than the wylex install and subsequent work on it. Hard to imagine worse really.

 

[novice]

Just to update on the substance of the thread. Firstly thanks for your time mostly giving constructive help.

The "borrowed neutral" turned out to be the result of the electrician (probably in the 90s) installing no less than three t+e cables in the consumer unit for the sole purpose of enabling the 2 way lighting in the garage:

1/ Going to the common of the first 1gang 2way switch
2/ Going to the common of the second 1gang 2way switch
3/ Going to the first lamp

The switches were connected in a standard manner with t+e connecting their L1 and L2 terminals. They had then joined the live of cables 2 and 3 within the consumer unit in connector blocks to complete (for the lives at least) a standard 2 way circuit (albeit inside the consumer unit!).

So I think what was going on was the neutrals weren't probably taken care of. I believe my task will be to ensure the neutrals and lives are properly connected in the old, "main" consumer unit so that I only need to run a single length of t+e to "my" consumer unit. That would have the advantage that only a single wire for N and E entering the RCBO so sidesteps the question of "what is a circuit" etc.

I'm sure most of you would have sorted this in 5 minutes. Took me hours but I enjoyed doing it and still not sorted yet but at least I think I understand what is going on.

 

[brightspark]

Best way sometimes is when it takes time as next time if you come across something similar it will make more sense quicker.

 

[binky]

Just to update on the substance of the thread. Firstly thanks for your time mostly giving constructive help.

The "borrowed neutral" turned out to be the result of the electrician (probably in the 90s) installing no less than three t+e cables in the consumer unit for the sole purpose of enabling the 2 way lighting in the garage:

1/ Going to the common of the first 1gang 2way switch
2/ Going to the common of the second 1gang 2way switch
3/ Going to the first lamp

The switches were connected in a standard manner with t+e connecting their L1 and L2 terminals. They had then joined the live of cables 2 and 3 within the consumer unit in connector blocks to complete (for the lives at least) a standard 2 way circuit (albeit inside the consumer unit!).

So I think what was going on was the neutrals weren't probably taken care of. I believe my task will be to ensure the neutrals and lives are properly connected in the old, "main" consumer unit so that I only need to run a single length of t+e to "my" consumer unit. That would have the advantage that only a single wire for N and E entering the RCBO so sidesteps the question of "what is a circuit" etc.

I'm sure most of you would have sorted this in 5 minutes. Took me hours but I enjoyed doing it and still not sorted yet but at least I think I understand what is going on.

Sounds like a DIY special, and definitely not something sorted in 5 mins. Oddly enough I encountered something similar 2 weeks ago.