consumer unit

[alcad]

The electrical installation in my wk end home failed the domestic installation inspection on the following points
The consumer unit which has a isolator switch and MCBs is mounted on a wooden frame(looks like original equip) which holds it off the wall by approx 20mm
One of the ring mains is broken to the effect that it's now 2 radials
I've been told that I should replace the consumer unit so that it is flush with the wall, and either find the break in the ring and fix, or put them on seperate 20A radials
I would like to know if the wood backing frame should be a failure, and if I replace the board with a new larger one and the tails of the cables are now too short, can I extend them within the consumer unit by using connector blocks?

 

[ban-all-sheds]

The electrical installation in my wk end home failed the domestic installation inspection on the following points
The consumer unit which has a isolator switch and MCBs is mounted on a wooden frame(looks like original equip) which holds it off the wall by approx 20mm

Can't for the life of me imagine why that's a "fail" - what comment was made, or what code given?

One of the ring mains is broken to the effect that it's now 2 radials

That is definitely not good.

I've been told that I should replace the consumer unit so that it is flush with the wall,

I guess if there's something wrong with what it's mounted on then that should be sorted, but it does not have to be flush - there is no requirement for this.

and either find the break in the ring and fix, or put them on seperate 20A radials

Yup. Or depending on floor area served, just replace the existing breaker with a 20A one if you've no spare ways. If you create 2 x 20A circuits then you'll have to find out where the break is anyway, so that you can label the MCBs to show which sockets are on which.

I would like to know if the wood backing frame should be a failure, and if I replace the board with a new larger one and the tails of the cables are now too short, can I extend them within the consumer unit by using connector blocks?

1) Why would you want a larger one?

2) No you can't use connector blocks in the CU - if the tails end up too short you should ideally replace them, but they can be joined in a service connector block.

3) If you do envisage fiddling with the tails, how do you plan to isolate them?

4) And in general, how do you plan to safely remove the CU and re-fix it?

 

[alcad]

The report just lists these items as requiring urgent remedial work
When I enquired why the wooden framed cu was a failure, I was told it was not acceptable under current regs, but no comment was made about the meter and the service cut out fuse being on a chipboard
The existing cu does not have any spare ways, hence the thought of replacing with a larger one
I had thought of just replacing the broken rind 32A MCB with a single 20A one , but was told that each circuit required its own protection-hence the need for a larger cu
When I referred to the possibility of the tails being too short I was refering to the circuit wires and not the meter to cu ones

 

[Lectrician]

If the ring is two radials, as in no continuity in any of the L N E, I would guess there is not a fault, but it was wired as two radials, and two 20amp MCB's would be the best and quickest option.

However, if the ring is only open circuit in the L or N, then there is no point splitting it into two radials, as you would need to find where the break was to make sure you also seperated the other L or N (depending on if it was the L or N split as a fault). If you have to find this, you may aswell simply repair.

 

[plugwash]

Even if there is no continuity in any of them you still really need to find the fault to make sure things are safe.

 

[Lectrician]

If there is no continuity is all three, I would reckon on it being two radials. Very little chance of all three having a break or becoming disconnected.

 

[plugwash]

what abotu the possibility of the complete cable being yanked out or cut through somewhere leaving live ends exposed?

IMO when an issue like this is found with a circuit it raises alarm bells about the standard of the installation and maintinance and so a complete inspection and mapping of the circuit is in order.

 

[alcad]

If the ring is two radials, as in no continuity in any of the L N E, I would guess there is not a fault, but it was wired as two radials, and two 20amp MCB's would be the best and quickest option.

However, if the ring is only open circuit in the L or N, then there is no point splitting it into two radials, as you would need to find where the break was to make sure you also seperated the other L or N (depending on if it was the L or N split as a fault). If you have to find this, you may aswell simply repair.

My understanding is that his tests showed that there was no continuity in the L,N, and E, and that instead of now being a ring main it is effectively 2 seperate radials, although I have not checked to cnfirm that he is right

 

[333rocky333]

sounds to me also, as others said.

It may have been always two radials and got bunched up to allow a cooker, garage or other circuit to be fitted at a later date

Inside the fuse cover is sometimes written the circuits and you may be able to tell from that what was original and if any have been altered.

some of them small wood back boards originally had 15a radial for downstairs and 15 amp radial for upstairs and two 5a for up and down lighting, and often got bunched up to create extra ways

 

[ban-all-sheds]

The report just lists these items as requiring urgent remedial work
When I enquired why the wooden framed cu was a failure, I was told it was not acceptable under current regs,

Phone him up - ask him to tell you which regulation.

The existing cu does not have any spare ways, hence the thought of replacing with a larger one

When you said "board" I thought you were talking about replacing the wooden board the CU is mounted on.

You should not DIY the replacement of a CU.

I had thought of just replacing the broken rind 32A MCB with a single 20A one , but was told that each circuit required its own protection

True, but that's partly tied into what makes a circuit. If you have both cables from 1 MCB you only have 1 circuit...

hence the need for a larger cu
When I referred to the possibility of the tails being too short I was refering to the circuit wires and not the meter to cu ones

They aren't tails.

If you decide to go for a larger CU, your electrician will resolve all the cabling issues. Not sure you should invite the guy who did the PIR to quote though....

 

[eyeofthebeholder]

this sounds bizarre and I hope its not correct regarding the CU mounting!

We have mounted our CU on marine ply which is about 15mm away from the wall. It has another bit directly above going up to the ceiling to cover the cables.

 

[alcad]

I had thought of just replacing the broken rind 32A MCB with a single 20A one , but was told that each circuit required its own protection

True, but that's partly tied into what makes a circuit. If you have both cables from 1 MCB you only have 1 circuit...

[

So if I was to overcome is objection to the wooden backing frame, by the use of stand offs made from pvc conduit I could run both radials off one 20A MCB. If so this would certainly be the cheapest option

 

[JohnD]

... the wooden framed cu ...

I have a feeling the wooden CU frame might be the back part of an old brown Wylex or similar

How about a photo?

We like pictures

 

[alcad]

... the wooden framed cu ...

I have a feeling the wooden CU frame might be the back part of an old brown Wylex or similar

How about a photo?

We like pictures

Checked with the guy who did the testing, Apparently the cu does not have a back and the wires could therefore chafe on the wall, cause a temperature rise and set fire to the wooden surround. The regulations call for cables to be enclosed, but not in the building fabric hence the failure
Ihave decided to get 3 quotes from local electricians to replace the cu
I would like to thank everyone for the advice given