Antennas, grain elevators, burning out radios?

[markscs]

I'm posting this here because I feel it probably has something to do with antenna grounding, so here goes....

What is the "proper" way to set up a POP on something like a grain elevator or water tower?

We had a situation a while back where we set up a small repeater with two Engenius EOC 3220 EXT radios, connected to an omni (AP), and one a grid (bridge), then connected them by crossover at the POE injector.

Worked fine... ...for a couple weeks or so, then the omni radio's ethernet port would burn out. So we'd replace it.. a couple weeks later, same thing. Didn't seem to be anything specifically that triggered it as far as we could tell (no lightning etc).

We replaced the mini repeater (which was just to do some cheap testing anyhow) with a 3 sector hyperlink array, surge protector at the antenna, grounded with thick cable to the structure itself, grounded the 5ghz backhaul antenna (surge protector at the antenna), and grounded the case of the Lucaya 4-port radio box. It's been a month or so and no problems since (knock on wood).

Lately we've started having a similar problem with a similar setup on another grain elevator (a test site) it had been working fine all fall but then just recently we've had to replace 3 radios in a span of a month.

So tomorrow I'm going to go and replace it with a two-port StarOS box, put arrestors on everything etc. etc. and hope I don't have to worry about it again until I have to replace the unit with one that has more antenna ports down the road. :)

Can anyone explain whats going on, and is the way "I'm doing it now" the recommended way? Oh, on the staros boxes, the ethernet is only used to power the unit (the data port on the poe injector is empty).

[Ick]

We had a similar experience on a grain elevator. We had a lot of strange things happening, power supplies dieing mainly. One day, as soon as we hooked up the ul connector on the card, the wrap board would go dead. As soon as we unhooked it, it powered back on.

This time of the year, they are moving grain form silo to silo which creates an amazing about of static electricity.

I hired an electrician to ground all of the hand rails on top of the elevator, then I grounded all of our equipment to the hand railing. I kinda questioned his means of grounding, he just tied it into the current electrical system ground (running 200' of large cable down the elevator into a grounding rod was not an option) But we have not had any issues since then, that was two years ago.

[Stratolinks]

Fifteen of our sites are on grain elevators. Many of them have been up since early 2002. Since then I have lost 2 Power Supplies (from nearby lightning coming in over AC line, both were easily fixed with a new fuse and a new MOV) and one, maybe two radio cards have stopped working over the years.

ALL equipment is inside metal boxes that are bolted to the steel structure. Power runs are in aluminum armored Tek cable. DC blocked surge suppressors are on all antenna connections. Yes you can get a lot of static from the moving of dry grain, but if all your equipment is tied to a common ground it shouldn't get into any of your equipment.

[therealboss]

................"SNIP"................

ALL equipment is inside metal boxes that are bolted to the steel structure. Power runs are in aluminum armored Tek cable. DC blocked surge suppressors are on all antenna connections. Yes you can get a lot of static from the moving of dry grain, but if all your equipment is tied to a common ground it shouldn't get into any of your equipment.

I agree, grounding is the key....

[gunther_01]

Part of the key is "common ground" Not just the same structure as I have found. If you run your grounds from the different arrestors. Run them to one place. Then ground that one to one point if possible.

But yes, Metal boxes, arrestors on everything in or out of that box, and bond it well.