Gary thanks very much--this clears a lot up. by luck i have done some of
this already.
73,
rob/k5uj
From: Gary Schafer <garyschafer@comcast.net>
Reply-To: garyschafer@comcast.net
To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
CC: towertalk@contesting.com
Subject: Re: [TowerTalk] grounding
Date: Sun, 09 Oct 2005 21:55:19 -0400
Hi again Rob,
Yes the ideal location for your coax lines to come in would be the same
place that your power panel is located. But in your case it is not
practical. The next best thing is to run the power for your shack over to
where the coax line bulkhead panel is.
The bulkhead panel is your single point ground position. All of the power
for your shack equipment comes from it. All of your antenna connections come
from it. Your tower ground should also be tied to it. You should have as
extensive a ground (many ground rods and radials) as you can manage tied
directly to your bulkhead panel with the shortest leads possible. Run them
separately to the bulkhead panel. Don't make a common connection of several
ground rods outside and then run a single wire to the bulkhead panel. You
will have a much lower impedance ground system if each ground line runs
directly to the panel.
You hook the green ground wire from your house power that you run over to
the bulkhead panel to it but not the neutral. It must float as it does
everywhere else. The bulkhead panel is treated the same as an electrical sub
panel would be as far as grounding goes. But your power protection devices
(mov's and or gas tubes) would go from hot to ground and neutral to ground
at the bulkhead panel.
By the way polyphaser makes an outlet box with protection devices in it and
a cord on it to plug into a distant outlet. The outlet box is to be mounted
right on your bulkhead panel along with the coax protectors and serves to do
exactly as I described above.
This is what a "single point ground" is. ALL connections go directly to it.
You can have as many grounds connected to the bulkhead panel as desired
going to all sorts of other places. But do not ground the rig to any place
other than the bulkhead. And don't connect the rig to any cable not coming
from the bulkhead panel.
To be legal as far as NEC goes you should also run a ground wire outside
from your bulkhead panel to your electrical entrance panel ground rod on the
other side of the house. With that kind of distance it is going to do little
as far as lightning is concerned but it does keep it at the same potential
as far as power frequencies and dc are concerned.
Due to the long distance between your bulkhead entrance panel and your power
entrance panel is the reason you need the power protection devices at the
bulkhead. You want no difference in potential at all among any lines going
to your rigs.
In your case a whole house protector would be good to also install at the
power entrance panel. That will help reduce any strike energy coming in on
the power line.
But your lightning protection for your rig will take place at your bulkhead
panel.
If you got your power from an existing outlet for the rigs you would have a
considerable distance between the power ground and your coax grounds. The
rig would be in the middle.
By the way did I also mention that the tower should have its own extensive
ground system right at the tower too?
Hope that helps.
73
Gary K4FMX
Rob Atkinson, K5UJ wrote:
>okay Gary, i'm going to be the stupid one and say that there seems to be
>contradictions in what you advise.
>
>let's say i have my service entrance, its ground rod and panels, on one end
>of the basement. the feedline bulkhead is on the other side of the
>basement. it sounds like you are advising that i run a shack service
>circuit across the basement and ground it to the feedline bulkhead which
>is bonded to the shack cabinets and a rod or rods outside. The circuit,
>60A let's say, would branch out to outlet boxes. this does not sound
>like a SPG in the conventional sense I've been led understand. it might
>be okay with a large copper strap below grade outside connecting the
>service panel ground rod and running all the way around to the feed
>bulkhead rod. otherwise it sounds like a double point ground. i have
>always been told that you MUST have everything--satellite, cable, tv
>antennas, phone, AC service, antenna feedlines, and in-laws coming in at
>the exact same grounded location so everything will be colocated and rise
>to the same potential. tnx for ur patience
>
>rob/k5uj
>
>
>From: Gary Schafer <garyschafer@comcast.net>
>Reply-To: garyschafer@comcast.net
>To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
>CC: towertalk@contesting.com
>Subject: Re: [TowerTalk] grounding
>Date: Sun, 09 Oct 2005 12:16:48 -0400
>
>
>
>Rob Atkinson, K5UJ wrote:
>
>>i'll try this again. my computer went nuts in the middle of writing this
>>before, and i had to reboot it.
>>
>>Gary, let me make sure i understand this:
>>
>><<<For example, it is not necessary to have the mains power coming in the
>>same place as the coax lines. Just run a power line from a convenient
>>place over the where you have your antenna entrance panel. Put your power
>>line protectors there. Now run ALL your shack equipment from that one
>>power point.>>>
>>
>>do you mean run a shack service line around outside from where the drop
>>and kwh meter are, to where the feedlines enter?
>>
>>rob/k5uj
>>
>
>Hi Rob,
>
>Run it anywhere that you have access. It doesn't need to be outside.
>The point is that you do your grounding and power protection at the
>entrance panel for your antennas. The cable entrance panel is your single
>point ground. You have no other path to your equipment but through that
>panel.
>Now an extensive ground system hooked to that panel would be ideal.
>
>73
>Gary K4FMX
>
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