Maximum distance for meter tails

[smiffey]

Hi All,

Im in need of a little advice, I've been asked to change a consumer unit that is over 3 meters from the main feed! The location is in fact in the basement of a shop down stairs! So if you need to isolate the tails you would have to gain access to the shop and then to the shops store room/ basement.

I understand that with all meter tails over 3 meters they need to have an additional fuse put in line like a kmf or something of that nature. But where do i actually fit it? do i need to put larger tails in as its a longer distance? do i fit the extra fuse in the basement as well?

Thanks in anticipation of any advice any one can give me.

 

[londonlec]

Metalclad switch fuse beside cut out, armoured to metal consumer unit within property.

 

[smiffey]

ok so the new fuse has to go next to the cut out but what about isolation for the people house who it is? any ideas?

 

[topquark]

Fit another isolator before the CU if you need it, what's wrong with the main incomer isolator in the CU?

 

[Draig Coch]

As a suggestion...
You can consider the fuse in the main cut out provides you with fault protection. You may have to confirm the cut out fuse value though somehow, unless you cater for the largest fuse rating. You then have to ensure that the cable can be isolated. If the LEB haven't fitted their isolation switch after the cut-out consider fitting your own lockable isolator as near as poss to the cut-out. That should be job done (Famous last words)

 

[smiffey]

Thank you everyone for your advice on this, so i am going to fit a fuse local to the meter tails of my own with a lower rating than one supplied. I think the one supplied is a 100 amp so i will fit a 80amp then normal with the consumer unit. I bet the customer isn't going to like the price of the 25mm tails and 16mm earth tho all that way... how much is everyone paying per meter where they are if people don't mind saying??

 

[topquark]

Thank you everyone for your advice on this, so i am going to fit a fuse local to the meter tails of my own with a lower rating than one supplied. I think the one supplied is a 100 amp so i will fit a 80amp then normal with the consumer unit. I bet the customer isn't going to like the price of the 25mm tails and 16mm earth tho all that way... how much is everyone paying per meter where they are if people don't mind saying??

With a local fuse, can you not use 16mm SWA from there?

 

[JUD]

As a suggestion...
You can consider the fuse in the main cut out provides you with fault protection. You may have to confirm the cut out fuse value though somehow, unless you cater for the largest fuse rating. You then have to ensure that the cable can be isolated. If the LEB haven't fitted their isolation switch after the cut-out consider fitting your own lockable isolator as near as poss to the cut-out. That should be job done (Famous last words)

DNOs will only allow upto 3 meters of the tails on the consumer side to be protected by their cut-out fuse. Any longer than this then you have to provide your own protection in the form of a switch fuse or similar (as smiffey said in the OP).

 

[04gallsopp]

they can be as long as they want but ive been told that it must have a isolator every 2 meters or like a rcd main switch

 

[Guest123]

they can be as long as they want but ive been told that it must have a isolator every 2 meters or like a rcd main switch

Post #8 is spot on. the advice you've received regarding an 'isolator' every 2 metres is nonsense I'm afraid.

 

[truckster]

You could use 16mm split

 

[smiffey]

ok im getting more and more confused the more i read this im sorry to say. I spoke to the chap today and the basement isnt used so i don't have to worry about using swa or anything. Am i right in thinking that if the main fuse is only a 80 or even a 60 i must put one in-line that is smaller not one the same size?

 

[Richard Burns]

Thank you everyone for your advice on this, so i am going to fit a fuse local to the meter tails of my own with a lower rating than one supplied. I think the one supplied is a 100 amp so i will fit a 80amp then normal with the consumer unit. I bet the customer isn't going to like the price of the 25mm tails and 16mm earth tho all that way... how much is everyone paying per meter where they are if people don't mind saying??

You have it there.
Switch fuse within 3m of the supply (with discrimination from main fuse), 16 or 25mm cable (split or SWA(£4/£8 per m)), depending on switchfuse rating, to CU (good idea to have a local isolator for convenience beside CU).
Should be good

 

[malcolmsanford]

Metalclad switch fuse beside cut out, armoured to metal consumer unit within property.

Just wondered why a metal clad CU there london??

 

[topquark]

I had assumed because it was better to terminate the armoured. The insulated ones are getting quite fragile these days.