[TowerTalk] grounding

Rob Atkinson, K5UJ k5uj at hotmail.com
Mon Oct 10 07:39:45 EDT 2005


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 at comcast.net>
Reply-To: garyschafer at comcast.net
To: "Rob Atkinson, K5UJ" <k5uj at hotmail.com>
CC: towertalk at 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 at comcast.net>
>Reply-To: garyschafer at comcast.net
>To: "Rob Atkinson, K5UJ" <k5uj at hotmail.com>
>CC: towertalk at 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
>
>_________________________________________________________________
>On the road to retirement? Check out MSN Life Events for advice on how to 
>get there! http://lifeevents.msn.com/category.aspx?cid=Retirement
>
>
>

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's FREE! 
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/



More information about the TowerTalk mailing list