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Posted By Topic: Multiple earth stakes for equipotential bonding

RyanMulgrave
Jan 17 2020 19:33

Hi there just wondering if you can put as many earth electrodes in as you want to earth a frame of a building if the building has a runnning earth as a supply ?

does this then become part of the MEN system ?
   

DougP
Jan 17 2020 20:33

Not sure what you mean really?
Is it a building that has an earth in the submain?
And you want to put in additional earth electrodes?
And connect those earth electrodes to the switchboard earth bar?

Presumably the building frame is also connected to the switchboard earth bar?

Why do you think you need the additional earth electrodes?

Is the building residential?


   

SaintAlan
Jan 19 2020 11:11

Some buildings like remote switchrooms have an earth rod at each corner and a cad-welded earthing ring running around the outside of the building. Any other earths must be bonded together at a main E bar to prevent voltage differences in fault or lightning conditions.
   

RyanMulgrave
Jan 19 2020 12:26

basically it is for a mine site donga.

running earth in submain.

have been asked to put in earth electrodes for lightning protection to the frame.
as the dongas are on concrete blocks and have no path to ground other than through the running earth.


   

DougP
Jan 19 2020 14:12

Sounds reasonable. I have no idea about the requirements for lightening protection so I'll leave it for someone else to answer.
   

OwenK
Jan 19 2020 23:26

Lightning protection is spelled out in AS/NZS 1768 : 2007. It’s not a mandatory standard and it mentions proprietary systems as an alternative. It’s worth a read, covers various different building constructions. For earthing a welded ring of earth rods fits in quite nicely with down conductors also connected to the ring. The lightning earth system is also connected to the electrical earth system
   

DougP
Jan 20 2020 12:41

Presumably you would also be installing surge/lightning protection in the sub board as well?
   

OwenK
Jan 21 2020 20:33

Considering that lightning protection is being installed then surge suppression should go in. Surge Protection Devices (SPD) installation is in the standard, section 5.6.3.1
   

AlecK
Jan 22 2020 08:24

Also in "3000"; 2.7 & App F.