250.32 Two or More Buildings or Structures Supplied from

Status
Not open for further replies.
Re: 250.32 Two or More Buildings or Structures Supplied from

The last thing I remember seeing about lighting was on TV (either the Discovery or Learning Channel). A stroke of Lightning consists of several strokes. The first stroke (I think its called the leader) actually travels from the ground up to the sky. Additional larger strokes follow, and if I remember right, they alternate flowing from the sky down and the ground up.

One person had taken a photo at just the right time to catch the leader traveling up.

Steve
 
Re: 250.32 Two or More Buildings or Structures Supplied from

Ed,
There is not Requirement that the grounded conductor be re-grounded at the second building.
If you pull an equipment grounding conductor to the second building with your feeders, you would then float or isolate the neutral and not re-ground it. The requirement for re-grounding is if NO equipment grounding conductor is pulled and there is no metal piping or continues metal paths between buildings. However in either case you still must establish a grounding electrode system for each structure.

John Cosmo
Montana State Electrical Inspector
 
Re: 250.32 Two or More Buildings or Structures Supplied from

John,
In my post of April 24, I was referring to the days when a feeder to a remote building was more often run overhead, using triplex, or even before that, single conductors on insulators, with no EGC.

Ed
 
Re: 250.32 Two or More Buildings or Structures Supplied from

Ed,
Forgive me, It was late and I thought you were confused about the requirements. I can see you are not, so again I apologize...

John Cosmo
Montana State Electrical Inspector
 
Re: 250.32 Two or More Buildings or Structures Supplied from

Steve66
Correct. Mike said the ground rods don't protect against lightning, but this is for a metal lighting pole, not a building with wiring and equipment. Actually the poster makes the point that a pole must have an equipment grounding conductor and the ground rod doesn't do much.
 
Re: 250.32 Two or More Buildings or Structures Supplied from

There are a lot of studies dealing with lightning and one of the results is how much they/we do not understand about lightning.
My understanding is that lightning discharges are a form of static discharge, where two dissimilar charges have a path with enough potential for the lightning bolt to occur. The two dissimilar surfaces can be almost any material, the material does not have to be metallic, hence trees, roofs and even flying planes are struck all the time.
The reason for the air terminals, down conductors and ground rods is to help create a low resistant path to try and direct the strike to earth.

Pierre
 
Status
Not open for further replies.
Top