[AMRadio] #4 wire from mains? - they gotta be kidding


Bill Smith hbco2 at sbcglobal.net
Wed May 9 23:57:09 EDT 2007


Don't be afraid to use large wire in primary feeds.  I have seen the result
of "skimping" with the result conduit noticeably warms after about 10 - 15
minutes of operation.  The worst consequence is a power sag when the
transmitter comes on with the result that in the extreme, contactors won't
operate correctly.  The wire tables specify the minimum wire size,
especially if long runs are contemplated (fifty feet or so).  You will never
regret using the next size, even if it is initially more expensive.   The
current price of copper does not make the decision any easier.

Bill



----- Original Message ----- 
From: "Bill Fondren" <bill.fondren at sbcglobal.net>
To: "Discussion of AM Radio in the Amateur Service"
<amradio at mailman.qth.net>
Sent: Wednesday, May 09, 2007 8:43 PM
Subject: Re: [AMRadio] #4 wire from mains? - they gotta be kidding


> Brian I think u answered a lot ur questions or concerns.   The transmitter
was designed for 24 hour / 7 day a week operation.  at 1000 watts.   I agree
# 4 seems overkill but Gates wanted to get as stiff a power supply to the
transmitter as possible.  Those transmitters were used in a lot of small
towns, mom and pop operations. The old branch circuit tables showed 30 amp
#10, 40 amp #8, 50 amp # 6 etc.  Then down at the bottom of the page the
small print said for long distance runs keep the voltage drop less than 3%
by increasing wire size.  Anyway from the distances u mentioned dont think u
will have a problem.  Dont forget to double the distance in making voltage
drop calulations because the current comes in on one wire and returns on the
other wire.   Bill Fondren   K5PML
>
>
> "A.R.S. - W5AMI" <ars.w5ami at gmail.com> wrote:
>     I've been reading the Gates BC-1T manual and found two instances where
> they state that #4 wire should be used. One says:
>
> "3) ...provide #4 or larger primary wiring from entrance box to
transmitter".
>
> What the heck am I missing here? My 200 amp mains (as the wire runs)
> to my shack junction box will be about 24 feet max, and then from the
> shack panel to the Gates will be no more than 12 feet.
>   -  -   -
>   Brian / wa5am
>
> -- 
> Suburbia is where the developer bulldozes out the trees, then names
> the streets after them. - Bill Vaughan
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