TN-C-S earth supply.

[se7aq]

On a TN-C-S the earth cable actually coming from the ground is about 6mm copper. 542.3.1 of the regs suggest table 54.1 (page 159) that 2.5 copper CAN be used if protected by corrosion by a sheath so the 6mm is fandabbydozy.?
Have I read that correctly..?

The ON-Suite guide suggests 16mm in its diagrams on p.15 of the guide.

 

[Octopus]

What size is the DNO fuse and what size are the tails?

 

[se7aq]

What size is the DNO fuse and what size are the tails?

Tails 16 DNO 100

 

[trev]

I think you're getting your earthing systems mixed up mate. You sure it's a TN-C-S?
By the way, the adiabatic equation is your friend

 

[Octopus]

what do you mean by "coming from the ground" makes it sound like a TT system!

 

[Engineer54]

On a TN-C-S the earth cable actually coming from the ground is about 6mm copper. 542.3.1 of the regs suggest table 54.1 (page 159) that 2.5 copper CAN be used if protected by corrosion by a sheath so the 6mm is fandabbydozy.?
Have I read that correctly..?

The ON-Suite guide suggests 16mm in its diagrams on p.15 of the guide.

Coming from the ground?? Are you sure this is not a TT earth rather than a PME/TNC-S system??

Personally i wouldn't have thought a 6mm main earth conductor would have been connected to a PME supply head by the DNO. Go and check the installation again.....!!!

 

[applemac]

A photo tells a thousand words, let the dog see the rabbit,

 

[se7aq]

Coming from the ground?? Are you sure this is not a TT earth rather than a PME/TNC-S system??

Personally i wouldn't have thought a 6mm main earth conductor would have been connected to a PME supply head by the DNO. Go and check the installation again.....!!!

What I meant is that the earth is part of the TN system and only a 6mm is coming from it.

Yep, adiabatic equation is our friend but ive had a situation with an assessor regarding the above but still the adiabatic was NOT coming up with the desired result.

 

[Meggerman]

What I meant is that the earth is part of the TN system and only a 6mm is coming from it.

Yep, adiabatic equation is our friend but ive had a situation with an assessor regarding the above but still the adiabatic was coming up with the desired result.

Is your earthing conductor coming from a rod, a service head cut out or clamped to a cable sheath?

 

[tony mc]

Re post 8 what sort of situation with the assessor.

If it is TNC-S should you not be looking at table 54.8 and not table 54.1.

You need to confirm the Earthing arrangement to receive advice on this issue!