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Fixed Wireless Equipment

Putting Water Towers to Work

Water towers are a great place for wireless ISPs to mount antennas, but there's a lot to learn about how to keep everything fastened where it belongs.

[January 7, 2003]

On the ISP-Wireless list in November, water towers were on the minds of several people. For one, KR asked:

"I was wondering if someone could tell me how you get the cable inside water towers that have internal access to the top. Do you have to drill a hole through the access door or what?"

[CC responded] "Depends on the type of water tower. Our present project requires installation of access ports beside the hatch. Water tower-certified welders will do it.

You probably shouldn't put it in the hatch because your cables would partly block access. According to our sources (such as they are), there is currently very little law covering non-water uses of water towers, but I heard third-hand that a federal law is going to regulate these safety concerns. Seems to me it should be state business, not the Federal government, but if they want to pass legislation to tell every salt-of-the-earth community in the country how to manage their water tower, I suppose there's nobody to stop them."

SP had another answer—and another question:

"The one we are just now going to get on has a small access hole around the collar of the cap. My question is how are people securing the cable from a catwalk railing up the bowl to the collar hole? Magnets?"

[JH advised] "Get a copy of the MTS [MTS Wireless Components, Inc.] catalog. They have all kinds of specialized hardware for water towers."

[B suggested, more concretely] "Bolt on cable clamps . . . Home Depot . . . Looks like a "C" with a screw in one side. About 54 cents each.

SP needed more information:

"I'll have to look again but I thought the outside of the bowl was pretty much a smooth surface. That's why I was wondering about magnetic hangers or clamps. I don't know what I would put a C-clamp on."

JH chimed in again with a more detailed proposition:

"How many cables, what size? If it's a handful of LMR400, I might suggest taking a grinder, knock off about 4 square inches of paint, epoxy something like an MTS CS-BS block to the tank surface, then re-prime and paint the spot after the epoxy cures. Then you can snap three butterfly clamps to the block. If you need more than that, maybe an MT-F1599 PVC sleeper with holes for 8 butterflies—and epoxy that to the tank. Nice thing about this approach is no welding to the tank. There's a lot of surface area to the tank, so presuming the epoxy bonds to the tank and the PVC, all you need to do is snap in the cable fastners as you need them."

BM took a different tack:

"I think this is a great opportunity for magnets (as opposed to using them for mounting antennas). Though you don't say what size cable or how many you are using, the magnet idea with either hangers or ty-clips would probably work fine.

Give the particulars (number of cables and size) and I'm sure I can give you a real economical solution."

[SP answered] "Yeah, cable size would help just a tad now wouldn't it? LMR-600; at the most three of them."

The discussion had moved on to issues of distance, etc., when JH came up with a third idea:

"Another method occurred to me for this. Tension a 1/4-inch wire-rope carrier wire from the ring to the railing, and lash the cables to that. It won't move. You can use a turnbuckle to adjust the tension, and either 3/8-inch UV-resistant cable ties or stainless banding to attach the LMR600. Probably a lot less work than epoxying hangers to the tank."

[BM concurred] "Yup...That should work."

[SP enthused] "Yeah, that's the ticket and I can find that on short notice at the local supply store. But does it have to be 1/4-inch ?"

[RB quipped] "Depends on what note you want it to play when the wind is whistling through it. I imagine that 3/16-inch will suffice nicely."

[BM went along with this] "Really, any cable 3/16-inch or better should work. I would use the plastic coated version to slow the rusting of the cable and to keep the cable from making a rust/water mark on the tank surface. Just make sure that the cable is flush with the tank bowl surface to avoid tripping hazards."

[JH made it unanimous] "I wouldn't go any smaller. Home Depot probably has it along with the clevis clamps. Not sure if they carry turnbuckles. If you have the equivalent of a Graybar Electric, you should be able to get some clamp-on U-bolts to attach to the railing, and see if they will let you drill a 3/8-inch hole in the collar to install the other one. Should only take an hour or so to install it."

—End