CU change

[Megaohm7]

I'm going to change a CU and it will be fitted in the same position as the old one? I think the meter tails maybe a bit longer than 3m. I spoke to the man putting in a DP isolator about this and he didn't seem too concerned about it.I'm using this job as my assessment so I would like it to be right..

 

[ProDave]

I thought the whole point was if the tails are over 3M they need a DP isolator fitted close to the meter.

Since you spoke to the man fitting a DP isolator, can we assume you have that now?

 

[fletchflash]

does it not need to be a fused isolator? Or is that depending on how much longer/smaller the tails are?

 

[danny7299]

I thought over 3m you need double pole switch switched fuse ??

 

[Theorysparky]

Bit longer than 3m ?

if its 3.2m i wouldnt worry too much

how much more is it ?????

 

[Megaohm7]

I would hazard a guess and say that it maybe just over the 3mtrs allowed but not much more..I will measure the tails as best I can if in doubt put in a switch fuse next to the meter I think..I might be surprised and find the tails to be less than 3 mtrs:Blushing

 

[Andy™]

over 3mtr and DNO usually want switch fuse. best contact DNO and see what they want

 

[Chr!s]

+1 with Andy, contact Dno

Ive spoke to dno in past, they are only responsible upto the service head, the meter tails and meter are the responsibility of the supplier, arguably the tails between the meter and cu are the consumers responibility.

The 3 meters is the length at which the dno will g/tee protection of the cable.

Now the way i see it is from the service head the installation needs to meet BS7671, now if you Ze is quite low for the type of fuse then i see no issue with longer tails providing BS7671 is met. The suppliers may require an isolator and it would be good practice to do so anyway.

If you ZE is not so low and little room for error then a switched fuse will be required to protect the remainder of the tails/ distribution circuit.