low resistance earthing design was required for a number of buildings in area where soil resistivity was 220ohm-m.
the area had a 450 meter fence on one side consisting of 2 in GI pipes and mesh of wire.this fence is almost in a straight line.each pipe is fixes in a concrete 2 ft deep while the total length of pipe is 12ft
when the fall of potential method was used to check the resistance of this fence by connecting c1 and p1 to fence wire the megger read 2 ohms
my Q is can we use this fence as a protective ground for the buildings near by

You can check IEE website..there is a section on there for Q&A..personally I'm unsure..but I hope this may help..

A big fat NOOO!!!, think of the risk not the resistance. Carryout a risk assessment, you will see why you cannot use the fence as the sole protective grounding system.

RGDS

In addition to Norman's comment, your protective ground should not rely on a non dedicated element which is totally out of control.

You can't predict the future existence of the fence (It might get removed later on during the building life cycle), how it will be affected by the weather, what maintenance actions will be carried on it, etc.

Bear in mind that after 5 years nobody will probably remember that the fence is actually your protective ground.

Agreeing with Norman!!! That's a huge NO!!!!!!