Board change on 16mm tails

[DNO1981]

Hello all

Just some input needed

I have 16mm meter tails & earth looks undersized coming unto the board also. I want the consumer unit changed, I understand that the tails need to be 25mm & earth 10mm I spoke with my electricity supplier who is going to get the technical department to call next Friday about changing these. Seems like it's going to take a while.

Can I get the board changed with the existing set up first, new rcbo board installed on the 16mm tails & current earth, then after upgrade the meter tails?

 

[MJPD29]

They don't nessecarily need changed to 25mm, have you confirmed the size of the fuse?

 

[DNO1981]

They don't nessecarily need changed to 25mm, have you confirmed the size of the fuse?

The fuse is 60amp
UK power networks won't upgrade this until tails are 25mm

 

[MJPD29]

Can't understand that, 16mm tails are absolutely fine with a 60a fuse. How did they come to that decision?

 

[DNO1981]

Can't understand that, 16mm tails are absolutely fine with a 60a fuse. How did they come to that decision?

We're having some outdoor heaters fitted & a board for a jacuzzi. We were told to speak with someone & noted the 60amp fuse & tails should be changed.

 

[MJPD29]

I'd love to know how they calculated that, 16mm tails are fine on a 80a fuse also. Is the board located beside the meter or further away?

 

[Dave OCD]

Outdoor heaters ? I can't speak my mind here....

 

[DNO1981]

I'd love to know how they calculated that, 16mm tails are fine on a 80a fuse also. Is the board located beside the meter or further away?

The board is just behind the meter. So I don't need to wait for any tail or earth upgrade. Its ok to go ahead with the 16mm tails, I think the tails to the Meter from the consumer will be changed anyway by the electrician. It'll just be the 16mm coming from the fuse to the meter which be 16mm. I'll get on this now o know I don't have to wait

 

[i=p/u]

they wont put 100A fuse in unless 25mm tails. As for the upgrade I'd check your bonding if you say has small earthing conductor.

 

[pc1966]

If it is, or soon will be, on a PME system (i.e. TN-C-S) then 10mm is the minimum extraneous bond size (Table 54.8) , and obviously that also applies to any incoming earth...

Also from the simple guide (Table 54.7, not adiabatic computation) for CPC size then for 16mm tails your main earth should also be 16mm, as it would be for 25mm tails.

For an existing installation without signs of thermal stress then often you would simply let it be, but if you are looking for a supply upgrade to 80A or 100A then it makes sense to check and impose the current regulations of cable sizing.