Lightning Arresters

[baaman]

We are getting wrote up for hooking up lightning arresters wrong. The engineer wants the bottom to go to the pole ground. All 3 straight to pole ground. The old way was to hook 3 together, than take each one to the system neutral. What are your thoughts. Thank you, Bob

 

[stevenal]

What are you protecting? If protecting an underground cable, connect to the cable shield. If a transformer, connect to the transformer tank. Best protection occurs when the lead length on both sides is kept as short as possible. Rules 1 and 2 also apply.

 

[baaman]

They are on utility poles, 5 sets per mile. Thank you, Bob

 

[stevenal]

Then you are simply protecting the aerial insulation against flashover. Is this a multi-grounded system with a low neutral? If so, run the pole ground conductor up past the neutral to pick up the arrester ground leads, bonding the neutral where it passes. I see no point in separately jumpering the arresters together.

 

[baaman]

Thank you, that answers my question. Bob

 

[wbd]

I would agree with Stevenal. That is the way my utility does it and I would suspect the majority of utilities do it.

 

[tesladog58]

As a distribution lineman for many years, we have always used, or installed a pole ground and bonded at the neutral, than installed a ground wire on the under side of the cross arm for the ground side of the arresters. this allowed for a short jumper wire from the line to the top of arresters. And also best to use compression type connectors, and split bolts

 

[baaman]

We use a bracket for both 3 phase and 1 phase. We are a Cooperative, so we make a circle ground or have 2 points were it is grounded. Thank you, Bob

 

[1capybara]

Im not sure of your jurisdiction, but NFPA 780 requires the downconductors to go directly to a pole ground. And they should ideally be in a symmetrical configuration, for ex., on diagonally opposite corners of a building or transformer. And then as baaman said, circle ground or two points grounded or ground ring, or radial grounds are also allowed.

 

[stevenal]

We're speaking of arresters, not lightning rods. Try IEEE C62.22 for an applicable US standard.

 

[tinfoil]

Split bolts have a habit of working themselves loose, so we will no longer use them here my utility for any grounding application.