[Mobile-Portable] What Gauge Wire?

D C *Mac* Macdonald k2gkk at hotmail.com
Tue Dec 4 22:13:41 EST 2007


Sorry to "reply" to my own email, but I just used the 
voltage drop site and made a calculation of what I 
expect may be a typical installation with RF deck 
mounted under the rear seat or even farther back. 
 
I assumed 12V, a power cable length of 15 feet 
(it WILL add up quickly), 25 Amps and #6 AWG 
coductors. 
 
Total voltage drop would be .36 Volts.  Not a problem 
for some rigs, but it might be marginal with the IC-7K. 
If tend to be O/C as I do, you may wish to go with #4. 
That would result in a voltage drop of .228 V. 
 
73 - Mac, K2GKK/5 
Oklahoma City, OK 
 
 
 
> From: k2gkk at hotmail.com 
> To: mobile-portable at mailman.qth.net 
> Subject: RE: [Mobile-Portable] What Gauge Wire? 
> Date: Tue, 4 Dec 2007 19:46:32 -0600 
> 
> I don't have tables readily available and can't confirm 
> the data below. HOWEVER, many times the voltage 
> drop is given for a certain number of Amps in ONE wire. 
> You have to double that to get the drop in both wires, 
> plus and minus. 
> 
> As for me, I'd use #6 at the smallest. 
> 
> 
> 73 - Mac, K2GKK/5 
> Oklahoma City, OK 
> 
> 
> 
> Date: Tue, 4 Dec 2007 19:30:06 -0500 
> From: doc at kd4e.com To: mobile-portable at mailman.qth.net 
> mailto:mobile-portable at mailman.qth.net 
> 
> Subject: Re: [Mobile-Portable] What Gauge Wire? 
> 
> Thanks, very helpful! Will also save that site! 
> 
> Question: What is the result when one parallels two wires? 
> e.g. If one parallels two #10 wires is the result a current 
> handling capacity of #8 or #5 or ??? 
> 
> Using the calculator at: http://nooutage.com/vdrop.htm, 
> I calculate a good cable would be #8 with just under 1/2 
> volt drop. 
> 
> I am assuming you are running about 20 amps with the 
> HF rig, 15 for the VHF rig and other accessories mentioned. 
> That gives an estimated current draw of about 35 amps. 
> At 12 volts, #8 wire for 8 feet will be about .432 volts 
> dropped.  
> 
> On the other hand, #6 wire will give you a drop of about 
> .276 volts.   On the other side of the equation is # 10 wire 
> with a voltage drop of about .7 volts.  Since #10 is rated at 
> 30 amps, I suspect you will want at least a #8 or larger wire. 
> 
> 
I hope this helps. 
> 
> Buck  N4PGW 


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