main earth size on TT system

[Mac1]

Having an argument.Don't have the BRB or the OSG to hand.Can someone give me a reg number about TT earthing systems and the minimum earth cable size you can use on a spike.I reckon it's 6mm,but i always use 10mm.Thanks in advance

 

[jl-heating]

agree but dont know the reg lol.

 

[Robojin]

Having an argument.Don't have the BRB or the OSG to hand.Can someone give me a reg number about TT earthing systems and the minimum earth cable size you can use on a spike.I reckon it's 6mm,but i always use 10mm.Thanks in advance

If this answers your question pg16 OSG fig2 states 6mm for Gas & Water, but does not specifically show CSA for the connection to the spike, but we might deduce not less than 6mm2 from the diagram provided, so if you prefer 10mm2 it's your call

Incidentally chapter 54 is the BRB section to look at, and calc based on the adiabatic equation as at a quick glance it's not in a handy table

 

[Apache]

I'm sure we've had this before

You might not even need 6mm

One of the electricity companies won't connect anything less than 16mm even on TT

 

[batty]

I'm sure we've had this beforeYou might not even need 6mm

One of the electricity companies won't connect anything less than 16mm even on TT

Quite correct patch that is EDF, anyway why would you not put a piece of 16mm in. Usually rod will be no more than a few metres from consumer unit so what are we talking about

 

[cheggers]

2.5mm protected 4mm unprotected

page 28 osg table 4.2

 

[spinlondon]

I guess it depends on what you call the conductor connecting to the rod.

A Main equipotential bonding conductor (MEBC) is required to be not less than half that of the Earthing conductor and not less than 6mm

 

[cheggers]

Page 23 bs7671

part 2 Definitions

Earthing Conductor - A protective conductor connecting the main earthing terminal of an installation to an earth electrode or to other means of earthing

 

[spinlondon]

There you have it, Earthing conductor.

If you size it at 16mm