Well, a few things to keep in mind, Mike:
. Each time an MOV breaks down, Its breakdown voltage decreases a
little, taking its break down voltage closer to the peak voltage of the line
cycles.
. Regarding ground rods - if the ground rods take lightning strikes,
the soil around the ground rod can "glassify" become glass from the heat of
the lightning surges. As the soil glassifies, the rod is then surrounded by
an INSULTOR - making it rather ineffective. It can be a pain, but it's
worth checking ground rods from time-to-time for degradation. A network of
multiple gro und rods can reduce the tendency to glassify the soil
surrounding the the ground rods because of the reduced current in each rod.
In very sandy soil, ground rods often need t go VERY DEEP! 20' or more!!
Many of the ground rods used by utility companies are designed with threaded
ends, to one can drive say 10' of rod, and then use a coupler to add another
10' and then repeat if necessary. I once watched a utility guy down in the
"sandhills" of NC crack the ground rod through the grass surface with the
"slam-pipe" and then literally PUSH the rod down 10' with his GLOVED HANDS!
He THEN ADDES ANOTHER 10' of rod. I don't know whe he might have reached
the water table or bedrock!
. In keeping with Tom's remarks, the meter-base suppressors ARE
common-mode surpressors that sit directly across the 240 volt line phases
with a direct common-mode ground return.
GL!
73,
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike
Waters
Sent: Saturday, June 27, 2015 3:37 PM
To: topband
Subject: Re: Topband: A Bit Off Topic
Hi Charlie,
Thank you very much for your advice. I agree, and this reminded me of my
forgotten intention to put MOVs (for now) in the meter pole panel. It's some
distance from the house and the wires run underground to the house panel.
I added a ground rod at that outdoor pole, and it's time to pour more
magnesium sulfate on it to help reduce the ground resistance. The #6 CU from
it to the ground bus is as short and direct as possible. The rod apparently
didn't do a thing, the lamp sockets still arced and CFLs still blew on my
living room ceiling fan.
I'm not real proud of the photo of my breaker panel on qrz.com. After
regularly losing various electrical devices in this house, it was a matter
of doing that or doing nothing. :-)
Maybe it's a coincidence, but since adding those MOVs, the lights no longer
brighten during a close thunderstorm. Of course, I cannot trust those.
I doubt that any $100 device is worth buying. You get what you pay for.
And I have a real problem with those surge suppressors with fuses in series
with the MOVs. Yeah, let's protect those MOVs, they're more important than
my color laser printer, computers, and ham equipment. :-(
73, Mike
<http://www.w0btu.com> www.w0btu.com
Having spent decades of my engineering career working with electric power
> distribution systems and equipment, especially electricity meters, I
> would have MUCH more confidence in a meter-base suppressor with a GOOD
> local ground and of course an additional power system ground back at
> the riser pole or pad-mount transformers on the distribution system.
> Of course, if He wants to, God has the punch to take that meter off
> the wall! AND none of this is going to help in case of a
> "power-cross" that I have also seen when a truck accidentally brought
> down a 7700 volt distribution line that fell across the residential
service drop!!
>
> I would have much less confidence in a device at the breaker panel
> with a longer, higher impedance, and potentially questionable ground
> return path through the residential wiring! Much better to take care
> of the surges right there at the load terminal of the meter!! That
> would prevent the surges from entering te residential wiring.
>
_________________
Topband Reflector Archives - <http://www.contesting.com/_topband>
http://www.contesting.com/_topband
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
