Cable calculation

[Deleted member 26818]

I agree PME is the way to go, like you say especially if livestock can come into contact with the installation

I give up.

 

[Nigel]

If either of you two actually want to look at the Regs, you will note that TN-C is where all of the system uses a PEN conductor and TN-C-S is where a PEN conductor is used only in part of the system.
Where TN-C-S is used the part of the system that uses a PEN conductor is on the supply network.

This is really basic stuff.
I’m not surprised someone who believes a 100A switch will trip doesn’t understand, but I am suprised at Essex.

A picture to help you.

 

[Nigel]

You are not using TN-C because the neutral and cpc are separate through the consumers installation.

The third letter means how the earth and neutral are linked at the transformer.

T = earth
N = Neutral
C = Combined.

This is true of both a TN-C and a TN-C-S. the S is for ‘seperate’ as the earth is then seperated from the neutral within the installation.

 

[westward10]

Why do you therefore insist they are the same.

 

[Nigel]

Why do you therefore insist they are the same.

I do not insist they are the same. I insist that a TN-C-S is a TN-C but then seperated. A TN-C cannot be a TN-C-S.

 

[westward10]

I do not insist they are the same. I insist that a TN-C-S is a TN-C but then seperated. A TN-C cannot be a TN-C-S.

Yes we know that. So OP have you worked out your cable size.

 

[Simon Burton]

Yes we know that. So OP have you worked out your cable size.

Taking that the Ib is 60amps (k.m.f il install with bs1361 60amp fuse in it) distance of 80 metres will be 35mm swa having a volt drop of 6v. I believe this to be the correct size, correct me if im wrong

 

[westward10]

How many cores are in the cable and what %vd are you using.

 

[Simon Burton]

How many cores are in the cable and what %vd are you using.

2 core single phase 3%

 

[Simon Burton]

How many cores are in the cable and what %vd are you using.

Would you agree?

 

[UKPN]

Il give you the scenario, stables in a field, e-on have been out and put a supply in a hut with a meter on and a one shot, main fuse is 80amps, the customer need a fuseboard putting in the barn, 75metres away, what size cable would i be looking at, ive done a calculation, 1 x swa cable 3 core, burried, ive use 80amp as the demand as this is the maximum at the origin and the cable size is coming back at 25mm. Is the right or is there some sort of diversity applied which would allow you todrop to 16mm. All that will be going in are sockets and light, quite a few to be fair but altimatley just wanted to get the armoures cable to the fuseboard and just questioning the size. Any help is appreciated

 

[UKPN]

25mmsq, 3 core, rcd at remote end.

 

[jackhammerJIM]

You also need to design the sub main zs to disconnect in the required time ...

 

[TimaT]

Has the OP learnt about the use of a ma

Yeah im now thinking degrade the fuse rating in my isolator, going off topic how do this work in domestic when the heas is a 60amp but the mainswitch on a db is 100amp

Figured this one out yet?

 

[telectrix]

Why are you not allowed to export the earth?

we will be able to after brexit.