GN8

[Rocboni]

Anyone know where I can get a free copy of IET GN8?

 

[Pete999]

IET and Free don't copute mate

 

[Rocboni]

I didnt think so, thought there might Be a download somewhere, £30 for a copy.

 

[Rocboni]

What I'm looking to understand is sub main earthing conductors. Is what I am saying right?

So a sub main to an installation not requiring bonding the earthing conductor can be determined using the Adiabatic equation or table 54G

However a sub main which requires a protective equipotential bonding conductor, to say a steel framed shed, this is determined by the size of the suppliers neutral conductor using tab 54.8 if PME or half the size of the main earthing conductor min 6mm not exceeding 25mm.

In this situation would your earthing conductor be the armour or a core of the supply cable and run the separate bonding conductor straight to the structural steel, water or gas? Or would you take it to the Sub main distribution board and them from there to the structural steel? Does this make the the earth terminal in the DB a EMT?

So if you had a PME supply with 95mm incoming neutral and the sub main requiring bonding to structural steel was a 5 core 16mm you would run a separate 25mm earth wire to the structural steel.

Is it as simple as that?