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Lightning and the Wireless Antenna

One member of the ISP-Wireless list asks if it's really necessary to install a lightning arrestor on an antenna, and receives a definite answer.

On the ISP-Wireless list in October, AM pleaded,

"Is it a real sin to save money by not installing a lightning arrestor on an antenna on the roof of a one-story building? What about not grounding the mast when a cable would have to be run under concrete to ground it? Would it be better to ground it to an electrical conduit on the roof, or not at all?"

A number of respondents urged AM not to cut corners on grounding:

[BM explained] "Nothing says you have to install a lightning protector, but you do have to ground the antenna. It's required by the National Electrical Code (NEC). If you have a customer that doesn't want to pay for a lightning arrestor, have them sign a waiver. If you have a customer that doesn't want to pay to ground the antenna, tell them it's required, and let them sign an affidavit saying they understand it is required and that they will install it themselves. Then at least the judge or insurance company will see the customer understood the risks and chose not to heed your advice."

[JS added] "It's a liability issue. The US electrical code states that externally-mounted antennae must have lightning protection. If you don't put in a grounding/arrestor system and they take a hit that destroys something, you are accountable."

JR suggested that it's okay to work with what's already there:

"If there is an existing ground rod, that's fine to use. Just make sure you wire-brush it and remove any residue. Make your connection, then coat it with grease to keep the contacts from oxidizing. Make certain that the ground rod system is in good shape and that the other grounds have a good contact."

BL contended that running your own ground is worth the effort:

"Grounding lightning to an electrical conduit might not be such a good idea. I prefer to keep it well away from everything else, on its own grounding rod. As far as I know, the lightning arrestor is not mandatory, just recommended for protection of the equipment—but grounding is mandatory."

—End

 

Related article:
	[Aug. 1, 2000]	Lightning