Mazhar,
I realized that what you gave was for a lower voltage. We normally use 5 or 6 disc insulators for 69 kV, and 42 feet is quite low for that voltage class. However, I was more concerned with the manner in which they are erected which I believe would be the similar. By the way, you mentioned the use of a lifter. By this, I suppose you were refering to a gin pole?