Home › Electrical Engineering Forum › General Discussion › Earthing strip size calculation. › Re: Earthing strip size calculation.

2011/11/30 at 8:45 am
#12691

electricalexpert65

Participant

Yes! Your interviewer was very correct! There is a very precise formula for sizing the earth strip:

S = I Root 't' / K

where, S is the cross sectional area of the earth strip, in sq.mm

I is the maximum anticipated earth fault current, in Amperes

t is the duration of the earth fault in seconds

K is a constant dependinng upon the material of the earth strip, type of insultaion & method of laying the earth strip (Pl. refer to IS 3043 for the values of these constants)