Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: paul.fr on 02/05/2007 13:11:38

Title: Why are power lines hung from pylons and not buried underground?
Post by: paul.fr on 02/05/2007 13:11:38

why are they overhead, and not in the ground?

Title: Re: Why are power lines hung from pylons and not buried underground?
Post by: eric l on 02/05/2007 13:49:18

I think that for starters they are easier to checkup and maintain overhead than in the ground.  Second, there is the problem of leakage (air is an insulator, "the ground" is not). 
In Belgium most of the household tension lines (220 V) are under ground; the requirements on insulation are very strict.  For a hight tension line, the mass of the insulator would be a lot higher than the mass of copper wire involved !

Title: Re: Why are power lines hung from pylons and not buried underground?
Post by: that mad man on 02/05/2007 15:41:42

It has mainly been done in the past because being overhead meant less disruption in building a grid, as opposed to digging things up and laying cables.

Another advantage of overhead cables is that they are suspended in "free air" which means the cable will run cooler and can have a smaller diameter than one buried underground.

Bee