16mm or 25mm tails plus when to install switch fuse?

[HappyHippyDad]

Afternoon all..

A couple of questions..

I shall be installing an 80A switch fuse after the cut out as both the supply and the CU are being moved and they will be greater than 3m apart. There will be approx 2m of tails on the outside wall in conduit and the remainder (approx 8m) will be between the floorboards (without insulation)

1. I am planning to use 25mm tails simply because this is recommended by the on-site guide and for rewires this again seems to be the recommendation, or rather the 'good practise'. My question is why would 16mm tails not be acceptable? If reference method C is used then 16mm has a CCC of 87A, also I believe the voltage drop is ok given a max demand of 80A (haven't got the tables to hand).

2. I can see where the incoming supply cable enters the house so I want to install and position the new meter box myself so that the DNO will have to 'shorten' their supply cable rather than joint it. The reason I want to do this is because I want to get my switch fuse in the new meter box before they fill it up, as they may not position the meter and cutout with my switch fuse in mind, whereas I will consider their needs.
Is it ok for me to install the meter box and pop my switch fuse in before they do there bit?

Cheers.

 

[Octopus]

What is the size of the dno fuse?

 

[telectrix]

usually 2" long and 3/4" diameter. :ihih:

 

[HappyHippyDad]

........................

 

[HappyHippyDad]

What is the size of the dno fuse?

DNO fuse is 100A,

Switch fuse is 80A.

 

[Plonker 3]

1. Come on HHD this is a simple calculation.

2. Phone them and ask them.

 

[HappyHippyDad]

1. Come on HHD this is a simple calculation.

2. Phone them and ask them.

1. I know the CCC works out fine Dillb (although in conduit (ref method B) the CCC drops below 80A) and the volt drop is ok, but wherever I look it states 25mm and I just wanted to know why? I suppose because of what could be added on at a later date. I'm going to install 25mm as I dont want any trouble if the assessor chooses this install to see (and the fact that for 2m the tails are in conduit and will have a lowered CCC (below 80A)).

2. I was/am going to do that Dillb, but not until monday so i thought I'd see what you guys do. I expect the fact that it involves the DNO will mean that sometimes its fine, sometimes its not

 

[Plonker 3]

Well you have answered you own question. The clue is in the name, on site guide

 

[HandySparks]

I say that what you're installing is a distribution circuit, not 'tails'. The tails are just the section between meter and switch fuse. So you just need to design your distribution circuit, including its overcurrent protection (your switch fuse), in accordance with the usual circuit requirements.

 

[Pete999]

usually 2" long and 3/4" diameter. :ihih:

Sarcasm aint dead then Tel

 

[Midwest]

2) In my limited experience on this subject, my DNO expects the customer to supply the meter box and fit it as well. And although they don't own it they have certain requirements, like only our equipment can go in there. But when I spoke to them about fitting switch fuse in there, in similar circumstance, they were okay with it. Best to give them a ring/email and agree what they deem acceptable, before their guys turn up on site.

 

[davesparks]

Which dno is it? You normally get a guide telling you exactly what they expect you to do before they arrive.

The basic idea is that you fit the meter box, the left hand side of the back board is reserved for dno equipment and the right hand side is for the consumers equipment. You got whatever you need and leave your tails ready for them to connect.

 

[HappyHippyDad]

Which dno is it? You normally get a guide telling you exactly what they expect you to do before they arrive.

The basic idea is that you fit the meter box, the left hand side of the back board is reserved for dno equipment and the right hand side is for the consumers equipment. You got whatever you need and leave your tails ready for them to connect.

Western Power.
The client hasn't received the pack yet.