That's great info! Thanks! I was going to ground the roof but I was afraid I'd be inducing transients into the ground "system" (using that term loosely - it's one ground rod) and maybe damage more than I already was. For safety the roof probably should be grounded, but as far as the gear goes that's off the roof already.
In considering grounding the roof I was wondering about what size conductors and how many should be used. I figured one would be way better than none, but considering the wavelength and impedance (inductance) of the wire I was wondering if I should use more than let's say just one #4 wire. Greg On Oct 5, 2010, at 11:06 AM, Jeromie Reeves wrote: > Ground the roof. I have a hay barn where there are some AC mains just > 14ft away and it induces about 80VAC to the roof. We first thought > there was a ac break someplace, but we shut down ALL the power to the > property. Unless the bread is in the weather head to the meter > base/breaker panel (all above ground) then we have a induced voltage > from the mains to the roof. When this site was first installed I was > completely below roof line at one end of the barn (40ft wide, 35ft > tall, mounted at the 15ft level) as it sits right up on a knob. Kept > losing ethernet ports even with grounding and suppressors. Figured it > had to do with the wood and poor grounding (via AC, back to the shop). > Drove a ground rod and tied to the power enclosure, radio enclosure > and directly to the antenna mounts. At the same time I moved up the > pole to the roof line (20ft) and got a shock that nearly killed me. > Not for the current, but because it was to my EAR. I jumped about 5ft > from the building and landed about half way down the fiber glass > ladder. All other times being on site a fully metal ladder was used > (13ft) and was far short of the metal roof. I was stunned to have been > shocked. After grounding the roof I have not lost a single ethernet > port since even with out grounding not counting after having the > ground line cut (farmer nicked the pole when loading hay, did not > notice the ground was cut). > > > > On Mon, Oct 4, 2010 at 8:49 PM, Greg Ihnen <[email protected]> wrote: >> Lightning took out my RB-750 today. This is the second one I lost to >> lightning. Are the RB-450's any better made or more resistant to lightning? >> >> I have protection, shielded ethernet cable and grounding but the gear is >> mounted up on a metal roof that is not grounded and when there's a nearby >> strike the roof is getting an induced charge and it's knocking out the gear. >> Besides losing an RB-750 I lost the ethernet port of a UBNT PS2 and it's >> power supply. >> >> Tomorrow the gear comes off the roof. It's going on a grounded pole. I have >> other gear on top of a grounded Quonset hut and there's no problems. >> >> Greg >> >> >> -------------------------------------------------------------------------------- >> WISPA Wants You! Join today! >> http://signup.wispa.org/ >> -------------------------------------------------------------------------------- >> >> WISPA Wireless List: [email protected] >> >> Subscribe/Unsubscribe: >> http://lists.wispa.org/mailman/listinfo/wireless >> >> Archives: http://lists.wispa.org/pipermail/wireless/ >> > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
