Date: Thu, 11 Jul 2013 08:59:49 -0400
From: "Stan Labinsky Jr." <K2STN@frontier.com>
To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] TowerTalk Digest, Vol 127, Issue 27
Message-ID: <675C4E0FEA3E4830A5F14788F2E82F75@stancommHP>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=response
Hmmm... took out normally rugged appliances. "Cook stove, dryer, etc."
These have, or should have, only one path to ground, back through the power
cabling.
Sounds like the strike came in on the L1 and L2, the two 120 volt lines.
Suspect that the jolt hit the pole transformer's primary and raised the
secondary voltage to a point where equipment insulation broke down... ouch!
Don't know that I'd blame grounding or the lack of it for that failure.
But probably easier for the power company to blame grounding than trying to
educate the victims on what really happened. They don't care why, they just
want it fixed!
Proper station grounding is aimed at making sure that no strike CURRENT
flows THROUGH the equipment.
The current is the bad guy. The voltage makes it flow.
Keep the potential difference to a minimum by causing the strike to bypass
the equipment... should be able to survive the strike.
Think, "putting all the equipment into a cocoon with only one connection to
the outside world and you'll get the picture on station grounding.
Stan
## standard procedure is to use HUGE fused MOV’s right at the entrance panel.
They are wired from L1 to neutral and also L2 to neutral. These are typ
130-140 v
rated. That way, you have 2 x series movs across the 240 line..and a mov
from’each hot leg to neutral.
Neutral and ground are bonded together in main 200A panel.
## Insurance companies like factory mutual will insist that telco’s in both
canada and the usa
use em. They are also alarmed. On 3 phase setups, 3 MOV’s used....and
also wired
hot to neutral. Ground rods used around the perimeter of a building.
The usual brand of entrance panel mov protection that is used is JOSLYN. Also
used
at all cell and microwave sites.
## I have 3 x 8’ copper rods at base of the tower..all cadwelded below
ground. Then another
rod 50’ away just outside the basement window. 2 ga Cu wire between this
rod..and the 3 x rods
at base of tower. SPG also bonds to rod outside window. Coax braid should
be bonded to both
top and bottom of the tower.
## I’m pretty sure just about every insurance co in Florida will make home
owners use movs on
main service pane.
Jim VE7RF
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