DC Cable Size question

[Quintrex4]

Hi,

I need to run 12v DC 0.16Amps/1.44watts a length of 22.9m, about 75ft, would light duty speaker cable: 14 strands. 0.16mm2 do this job or should I use something larger?

http://www.bunnings.com.au/antsig-100m-grey-speaker-cable_p4430106

Thanks

 

[hevans1944]

It depends on how much resistance 22.9 m of cable has. What the heck is "bi-metal" speaker wire? Copper-clad aluminum perhaps? I would use 18 AWG copper zip cord.

 

[(*steve*)]

OK, first thing, is it 14 strands per conductor, or 7 per conductor?

Let's assume it's 7. So the cross-section is 7 * 0.16 = 1.1mm^2 so the effective diameter is about 1.2mm

The resistance of this is probably something like 0.017 ohms per metre. The total length is about 46m, so the resistance is around 0.78 ohms.

At 0.16A, the voltage drop will be 0.13V. That's probably not significant.

 

[(*steve*)]

What the heck is "bi-metal" speaker wire?

Good point. I assumed copper.

 

[Quintrex4]

OK, first thing, is it 14 strands per conductor, or 7 per conductor?

Let's assume it's 7. So the cross-section is 7 * 0.16 = 1.1mm^2 so the effective diameter is about 1.2mm

The resistance of this is probably something like 0.017 ohms per metre. The total length is about 46m, so the resistance is around 0.78 ohms.

At 0.16A, the voltage drop will be 0.13V. That's probably not significant.

Great! Running off limited information from the suppliers site. 0.13V drop is insignificant for what I need it for.

Thanks for your help.

 

[(*steve*)]

That assumes it's copper. For aluminium, the resistance is just under double copper's.

The voltage drop will probably still be under 1/4 of a volt.