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Surfin’: Got Good Ground? Not So Much

08/05/2011

By Stan Horzepa, WA1LOU
Contributing Editor

This week, Surfin’ readers share war stories that are grounded in reality.

Last week’s “Got Good Ground?” resulted in two complementary war stories showing up in my e-mail this week.

Paul Mulford, KC8YHW, wrote: “Stan, you got my attention, now a short ’splainin’, as Ricky used to say to Lucy. In some areas of the country, mostly rural, the power companies do not maintain their grounds very well. My wife and I are the last customers out a run. Our poles have a top wire, and slightly lower, a ground or return for the transformer. Each customer or pair of customers has a transformer.

“Let’s say that at some transformer, there is a high resistance connection to the return path, so the ground wire stapled to the pole will use Earth as the return path. This ‘stray voltage’ can get quite high. I have measured 900 V from a ground stake to neutral. A cow getting milked may get a shock from the milking system; the cow does not like the shocks and milk production will drop off. Watering troughs can also get charged, so that the cow gets shocked when getting a drink of water.

“Back to my situation: Out at the barn, I have 18 V between ground and neutral and an ac ammeter shows about 15 A. The ground at my tower to the electrical system ground shows 40 V. So what do I ground to? To get around what is ground, I use an inverted-vee or loops, so I do not have to connect the radio to ground. I do have all feeds going through spark gap arrestors; if I do not isolate the radios and their feed lines, I get reports of a hum on my signal.

“By the way, the NEC is not a law, but is a code for insurance. It was written by Underwriters Labs, which is funded by the insurance industry. The code is written so if your house burns down from a lightning strike, they want to know if it was wired to code. The reason I have my shack in the barn is when we take a hit, we will still have a house.”

Jo, KF4OBF, and Henry Wyatt, K4YCR, wrote: “Lou, I read it with interest. Everything else fails when you have done the best with grounding and the power company has an open neutral -- all bets are off! We had a massive hit at 11:25 PM on Wednesday, July, 20. We’re still finding things that don’t/won’t work. Antennas were disconnected, but the surge/lightning got many things via the telephone, cable, serial ports or power lines. The FT-847 has to go back (no audio or keying); K3-output module (works QRP); two computers and UPSs.

“The electrician comes this Thursday to replace the attic fan and 15 switches. Two fluorescent ballasts and many CFLs went (with the essential smoke released). It blew the telephone interface box and the sprinkler control box right off the side of the house! It also blew the bottom off the 32-year-old TV rotor on the tri-band quad; I can’t even turn the control knob. I had polyphasers on all four coax leads which were disconnected from the equipment. All the antennas work except the vee beam; it’s controller exploded (it was grounded, too).”

Curious, I looked up the war storytellers on the ARRL website’s call sign search application, then I plugged their home addresses into Google Maps to see where they lived. According to my interpretation of the maps, Paul Mulford lives in a very rural area surrounded by farms (and more farms), whereas the Wyatts live in a rural neighborhood of suburban homes on one-to-two acre lots.

Thinking back to my first radio station -- a hunk of thin wire loosely attached to a furnace register serving as ground -- causes me to take pause.

I leave you with a website that may add to your education regarding proper grounding: Recommended Grounding Guidelines from the National Lightning Safety Institute.

Until next time, keep on surfin’!

Editor’s note: Stan Horzepa, WA1LOU, has had lightning damage via the phone line and the power line, but never the antenna line. To contact Stan, send e-mail or add comments to the WA1LOU blog.



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