Options for Moving a CU

[SparkieMarky]

Hi Folks,

Be gentle with me it's my first post! And I can't stress highly enough this is purely a hypothetical question as I am genuinely interested in how others would approach this example. You have been asked to move a domestic CU from its current location to a new position. The CU contains the usual mix of final circuits, 2 x lighting (1.5mm), 3 x ring circuits (2.5mm), 1 x immersion heater (2.5mm), 1 x cooker (10mm), 1 x hob (10mm) etc...

Obviously the current cabling will not magically stretch to a new location so a number of circuits will need to be either extended or have new cabling run from the new CU position. This is assuming that there is enough head room in the installation design to allow the cables to be extended.

So my question is what would be your preferred go to method for addressing this type of job (appreciate all jobs are different but this is purely hypothetical) and we are assuming that the installation is in good order, there are no bodges etc.?

Personally I have done them in the past where I have replaced the cabling back to the first leg on each circuit and often complete circuits (once you start down the rabbit hole and uncover some of the crap that's out there you can't just leave it - well I can't .

The supplementary follow up question is what would be your preference if you had to move the CU but couldn't mount an enclosure in the position of the old CU. Thinking of the CU high on the wall in a room and the householder doesn't want to have anything there anymore as it spoils the ascetics in their newly decorated room...

 

[SparkieMarky]

I came close to the Wago's and Connexbox enclosure, but as I (and others) have suggested reroute cables or replace initial sections of finals. Probably remove over half the need for connections then.

Yep, this is typically what I have tended to do in the past as never been a huge fan of lots of connections but have used the odd wago box when necessary for a lighting circuit or the leg of a ring when it would be just that bit too disruptive.

This was one of those things I ended up mulling over as I have been off sick this last week or so and was intrested in others take on things (made a change from looking at the 18th ed or doing the odd online practice tests). So knowing that we often tend to stick to the way we do things it’s sometimes good to have a different perspective. After all it can get you out of a hole at a later date.

 

[Midwest]

ConnexBox sell an enclosure (plastic) or used to, which you can install Wago Top Job din rail mounted connectors. Bit expensive mind, about the price of a CU.

 

[SparkieMarky]

ConnexBox sell an enclosure (plastic) or used to, which you can install Wago Top Job din rail mounted connectors. Bit expensive mind, about the price of a CU.

I hadn't seen the ConnexBox enclosure although familiure with a lot of the other wago boxes. Its certainly a reasonable option if distrubption is not an option. Certainly gives to option for a neat job all though the knockouts look a bit large for my liking.

 

[BruceBanner]

In regards to the 3 meter rule dno's apply about switch fuse requirements if ccu over that from intake. Had to query wpd earlier in year about a job I had which simply would not accomote it. Advice was that they did not stipulate this, & as not part of their or supplier installation it was nothing to do with them & bs7671 applies. their only stipulation was that the meter had to be within 3 meters or their measures applied. Probably get shot for this but wanted to put it out there.

 

[Midwest]

I hadn't seen the ConnexBox enclosure although familiure with a lot of the other wago boxes. Its certainly a reasonable option if distrubption is not an option. Certainly gives to option for a neat job all though the knockouts look a bit large for my liking.

Yep does look a neat solution. They did used to post some photos of install in such a situation, but after A3 came into being they had been removed.

I queried the use of a plastic enclosure directly above a new A3 CU with my scheme (this will start the mud slinging!). Their guidance, was then (just after A3) was that the designer would have to consider reg 421.1.201, and whether it applied in such a case (yeah yeah, I know it applies to similar switchgear assemblies etc, etc).

I contacted Connexbox, who weren't impressed with that guidance. I did follow up the guidance from the scheme, but in the end didn't get the job. It was then I noted the pics removed from Connexbox site; wonder if they've been reinstated?

 

[SparkieMarky]

Yep does look a neat solution. They did used to post some photos of install in such a situation, but after A3 came into being they had been removed.

I queried the use of a plastic enclosure directly above a new A3 CU with my scheme (this will start the mud slinging!). Their guidance, was then (just after A3) was that the designer would have to consider reg 421.1.201, and whether it applied in such a case (yeah yeah, I know it applies to similar switchgear assemblies etc, etc).

I contacted Connexbox, who weren't impressed with that guidance. I did follow up the guidance from the scheme, but in the end didn't get the job. It was then I noted the pics removed from Connexbox site; wonder if they've been reinstated?

Not sure if they are the same pictures but they certainly have ones showing it installed directly above a CU altough not sure that its not a pre A3 plastic CU (but don’t use crabtree stuff much theses days myself). I had also been mulling over the issues around the material of the enclosure and A3

 

[Midwest]

Not sure if they are the same pictures but they certainly have ones showing it installed directly above a CU altough not sure that its not a pre A3 plastic CU (but don’t use crabtree stuff much theses days myself). I had also been mulling over the issues around the material of the enclosure and A3

Ahhh, they're back then. Certainly removed from their site once. Perhaps they've had a word!

Certainly doesn't seem to be covered by 421.1.201, but I always thought it wasn't within the 'spirit' of A3, especially directly above a A3 CU.

If your in a scheme, email them & seek guidance, if your concerned.