[TowerTalk] Coax as powerline

[Roger (K8RI)]

> PLEASE DON'T DO THIS!!

I'd restate this although I do agree with the above statement.

If you do run powr through coax (It'll probably handle about the same as 
#14, but I have not checked the resistance per foot of the braid)

HOWEVER you will most likely be the only one who knows these leads have 
power on them and should something happen to you who is going to take this 
thing apart?  Your heirs? Some one who purchases the property from your 
heirs? Some teenager who is happy to get the coax? Which ever, the likely 
hood of them grabbing a bare HOT wire is quite high. Who will be liable? 
You or possibly your heirs? Or maybe some day many years hence when your 
memory isn't what it used to be, you hobble out to the tower and say, "Now 
why did I leave these pieces of coax out here? I think I'll just pull them 
out."  <ZAP!>

Although the idea will probably work even though I'd bet it's against most 
codes, it's definately a *serious* safety issue.

Yes, copper is expensive, but it's cheaper than the injuries a makeshift 
replacement could cost.  Possibly, scrounging through the local contractors 
might find some left over pieces, or a good price on some excess. Ask 
around, some one in your club or at a swap may have some cheap or to give 
away.  Don't rule out MTW wire as well. This is sometimes available for a 
few cents a pound when pulled out of industrial projects.  Often below the 
price of scrap copper.   I *used* to get MTW up to #4 or 6 (been a while) 
from surplus where I worked for about half the price of scrap.  I had 
literally thousands of feet of the stuff that I used or eventually gave 
away.
>

> I used to work as an engineer at a radio station and someone before me had
> used
> 2 conductor with grounded shield wire for AC in some places. It was DAMN
> annoying

I'd think that would be an understatement.

> to have to check EVERY (supposedly audio) wire with a meter before messing
> with it.
> There were literally MILES of wire run over the drop ceiling and any one 
> of
> them could
> be AC hot. I wanted to shoot the person that did it!
> In my opinion, it's better to have AC on AC type wire and RF on RF type 
> wire
> just for
> sanities sake.

And your insurance (including liability) is still most likely valid.

Roger (K8RI)

>
> RoD
> KD0XX
>
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com
>> [mailto:towertalk-bounces at contesting.com]On Behalf Of Jim Brown
>> Sent: Monday, April 14, 2008 2:41 PM
>> To: towertalk at contesting.com
>> Subject: Re: [TowerTalk] Coax as powerline
>>
>>
>> On Mon, 14 Apr 2008 09:53:08 -0600, Doug Renwick wrote:
>>
>> >Has anyone successfully used ca RG-8 or RG-11 center conductor only to
>> >carry 120 or 240 volts in place of an underground power cable?
>>
>> There are several issues with this one. First is the obvious one of
>> moisture. Second -- is the coax rated for carrying mains power? If you
>> ever had a problem (lightning, a fire), there could be serious legal
>> and/or insurance issues if it is not.
>>
>> Third -- NEUTRAL is NOT GROUND. For a 120V circuit, you MUST run a phase
>> (hot), a neutral, and an equipment (safety) ground. The ground may be
>> connected to the earth (it MUST be connected to the power system earth).
>> The neutral MUST NOT be connected to ground or earth anywhere. It
>> can only
>> be connected to the neutral bus in the panel, and to the neutral terminal
>> on the outlet (or load) at the other end.
>>
>> Likewise, for a 240V (only) circuit, you must run two hots ande a ground.
>> And if you want to run both a 120V load and a 240V load, you must also
>> pull a neutral.
>>
>> Fourth, the most "noise-resistant" way you can run a line like this is as
>> a twisted pair for the phase and neutral, with a third wire as the
>> equipment ground. If you ran this with coax, it would have to be as two
>> parallel runs of coax, with one center conductor being the hot (phase),
>> the other center conductor being the neutral, and the shields being the
>> equipment ground. The twisted pair is actually FAR better at rejecting
>> power-frequency magnetic coupling than the coax.
>>
>> 73,
>>
>> Jim Brown K9YC
>>
>>
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