# DC wiring ?



## Ky-Jeeper (Sep 5, 2010)

I'm curious about the positive and negative cables. Which carries the amps? I know the positive from what I always seen is fused? Does both cables actually need to be the same gauge ?

TIA Ky-Jeeper


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## Gary in ohio (May 11, 2002)

DC power flows down both cables so cable size needs to be the same. You will find many DC applications fuse both the positive and negative leads but one will stop the flow.


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## FarmTechnician (Dec 25, 2014)

Yes both cables need to be the same gauge. Amperage is the amount of current flowing throughout the circuit. The actual flow of current moves from negative to positive.


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## Ky-Jeeper (Sep 5, 2010)

Curious which wire heats up, or both?


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## FarmTechnician (Dec 25, 2014)

Both wires heat up. The wires act as a resistor. Heat is generated wherever there is resistance. 

Interesting to note, when Edison was playing around with different lightbulb filaments, he noted that filaments tend to burn out near the positive side in DC lamps.


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## Jim-mi (May 15, 2002)

If you are concerned with the wires heating up, then your wire gauge is too small.


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## wy_white_wolf (Oct 14, 2004)

Gary in ohio said:


> DC power flows down both cables so cable size needs to be the same. You will find many DC applications fuse both the positive and negative leads but one will stop the flow.


True only if you have 1 positive lead. If you run multiple positives to different loads your ground needs to be large enough to handle all the loads.

WWW


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## spacecase0 (Jul 12, 2012)

the big reason to fuse the + and - wires is if you run into a situation where another connection is made to something else (like an antenna ground connection on a radio). 
if you had no fuse on the - wire and touched the - power wire to the battery +, then things would just melt. 
I usually have these issues in low light levels where many things are getting connected together.
also remember that many solar charge controllers are + ground, 
so fusing the + does you less good than fusing the - 
and likely everything else you connect to it will be - ground, 
so unless you have a very small simple system that is not mounted anywhere near conductive items (like a car or metal building) it is a good plan to fuse the + and - wires


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## Ky-Jeeper (Sep 5, 2010)

Interesting info. I don't have any wire yet. I was curious to see if I could drop wire size on one or the other. I definitely want correct wire size, but If I can safety go smaller I would. As of now I will be using the same gauge. Thanks everyone.

Ky-Jeeper


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## Gary in ohio (May 11, 2002)

If your going to splurge on a solar power system do it in the wire... 
an example I had recently 40ft run of 10 gauge wire would drop 2 volts under load.
The same run with 4 gauge wire only dropped 1/4 volt under the same load. 

Thats a lot of loss and its all going into heat.. When your at 120v a couple of volts is fine loss, but when your at 12v and loose 2 volts your devices may not work at 10v


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## Jim-mi (May 15, 2002)

There are wire loss charts out there which you need to consult.
You need to know the current for a circuit----PV panels to house for instance...
The length--distance.

For instance; for a wind turbine I went with 1/0 instead of the chart calling for 4 gauge. . . . . . . . the line loss there is NOT a factor........


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## farminghandyman (Mar 4, 2005)

I think it is a fairly common miss conception, 

As I was once told by a licensed electrician once years ago, 
that the white or neutral wire in a AC system did not carry any power as it was used up in the device, *THIS IS WRONG*, it does carry power, just as much as the HOT wire,

both wires carry amps the same amps, this is how a ground fault circuit works, it measures the electricity going in and that which is coming out and compares it to each other, and if it not the same it breaks the circuit,

I think some of what leads to that kind of an Idea, is that the white (neutral) is in common with the ground, thus one will not read that it is carrying electricity, but it is carrying just as much as the hot (black) wire, the black but because it is not in common with the ground one can read it, so it can be miss understood that the white is not carrying power in the same way as the hot is, 

DC power is the same in that regard, 

one thing that some times gets in the way is the some times down sizing of the neutral wire in a 240/120 volt circuit, and the reason for that is that the two hots (black or black and red wires) are carrying most all the amps in a balanced circuit, when the circuit is unbalanced then the white wire carries the part that is unbalanced, this is for a transformed (AC) circuit with a center tap, NOT DC

a electrical circuit is much like a hydraulic system X amount of oil comes in to the (hydraulic tool, say, motor), the same amount has to leave, the motor that comes in to it,


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## Ky-Jeeper (Sep 5, 2010)

Going with 1/0. That way I can add on every so often. I'll just shell out the cash and be done.


Thanks everyone,
Ky-Jeeper


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