Best Stranded Copper wire gauge for Cigarette Lighter Accessories

Thread Starter

Lumenosity

Joined Mar 1, 2017
622
I'm going to install a new USB / Power outlet in my vehicle.

It consists of two USB A sockets rated at 2.2Amps each AND one standard size "Cigarette Lighter" socket (amp rating unknown)

To power this, I intend to run positive and negative wires directly from the vehicle battery (fused of course) to this new USB panel.
The total distance is approximately 7 feet.

What I'm wondering is what is the MINIMUM gauge of stranded copper primary wire I can safely use for this?

I have 16ga primary wire on hand but I'm concerned this may not be sufficient. Surely 14ga would be adequate?

Thanks
 

Thread Starter

Lumenosity

Joined Mar 1, 2017
622
After some research, it seems that I might need AT LEAST 14GA for the cigarette outlet because sometimes I may plug an Igloo 26Qt travel refrigerator into it.

Maybe even 12GA
 

Thread Starter

Lumenosity

Joined Mar 1, 2017
622
12ga it is.

Then went to order some 12ga primary wire ....seems there's some kind of shortage / price spike?
Maybe due to the hurricane in the Southeast? (or the recent flooding in NC?)
 

Reloadron

Joined Jan 15, 2015
6,066
You should be able to buy AWG 12 or AWG 10 THHN or TFFN stranded wire by the foot at Lowes, Home Depot or any home improvement or hardware store. I just bought a bunch of #12 and #6 at my local Lowes. Buy an inline fuse from any automotive audio / sound shop or automotive parts store and make sure you use quality copper lugs to connect to the battery.

Most cigarette lighter type utility outlets are rated at 10 Amps maximum so really for a short run AWG 12 should be fine.

Ron
 
Last edited:

shortbus

Joined Sep 30, 2009
8,820
You should be able to buy AWG 12 or AWG 10 THHN or TFFN stranded wire
While that will work, it isn't the same as car wire. Wire for cars has many more smaller strands in it than the kind you get a the hardware store. It is much more flexible and less prone to fatigue from the vibration in a vehicle. The car parts stores will have the proper type.
 

DickCappels

Joined Aug 21, 2008
7,743
The minimum wire gauge related to the ohms per meter. The ohms per meter can be calculated from the input voltage and maximum permissible drop, including the drop across the fuse and socket and the length.
 

Reloadron

Joined Jan 15, 2015
6,066
While that will work, it isn't the same as car wire. Wire for cars has many more smaller strands in it than the kind you get a the hardware store. It is much more flexible and less prone to fatigue from the vibration in a vehicle. The car parts stores will have the proper type.
Good point. Also, for a vehicle like a car I seriously doubt your actual run will exceed 20 feet. That said by the time you get from battery, through firewall to front dash you always seem to use a few more feet than anticipated so allow a few extra feet when you buy.

Ron
 

bwilliams60

Joined Nov 18, 2012
1,419
You can safely run 10 - 15 amps a distance of 10 feet safely using 14 gauge wire.
Place a fuse inline from a reputable fuse company that is roughly 20% higher than max current draw.
If you are running general purpose primary wire, the rating should be GPT. If you are worried about temperature or special applications, I can probably line you up with what you need.
As for where to get it? You can generally source it from any auto parts store or warehouse. This is where all the auto repair shops buy it from.
 

Thread Starter

Lumenosity

Joined Mar 1, 2017
622
Usually I buy my Primary wire from DelCity.com

But I found a massively great deal on RED 12GA Automotive Primary wire on Amazon at 18 cents per foot (delivered) so I bought 100 feet.

Right now, DelCity wants 30 cents per foot for BLACK 12 GA Primary Automotive wire and 25 cents per foot on RED. Why Black is more expensive I have no idea.

But, there is no electronics law saying I can't use red for both Positive and Negative leads. So I probably will, and wrap black electrical tape around both ends of the one I plan to use as negative....for identification.

Eventually the price of BLACK primary wire will probably return to normal then I'll but 100feet.
 

Reloadron

Joined Jan 15, 2015
6,066
A little surprised no one's posted up the electronics law saying you can't.............
What electronics law? It would be a standard or specification and not a law if it did exist. Your car or truck so your rules apply. As to price difference based on color for the same wire you would do better to ask the vendor as I have never seen a price change based on insulation color.

Ron
 
There is a calculator here: https://www.powerstream.com/Wire_Size.htm

Automotive wire tends to have a heavier insulation. It's not tin coated for whatever reason. Minimum should be about 18 AWG and stranded. The flex of the wire depends on the number of smaller strands and size that make up the equivelent guage. Make sure your connectors or terminals are sized properly.

You may want to consider adhesive heat shrink which keeps out contaminants. Road salt and water with dissimilar metals make a battery. The potential for corrosion depends on the work functions of the metals.

Lighter sockets are likely designed for 15 Amps. Make sure the wire fits. If you can;t measure, you can always take a pic of what you want to measure with a ruler. Then blow it up with your camera or your laptop and measure.

I'd go for 20 A. The voltage drop depends on the length of the wire. 3% is common for AC wiring. Don;t know for automotive systems.

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Finally, make sure the USB gizmo's your installing actually work for your devices. Check both ports. A USB gizmo to measure V and I will help with that. Make sure your devices are charging. I have a 120/12 in to USB charger with 2 ports. Both ports will charge a GPS without issue. Only one port will charge an Android phone. They are not labeled. They are now. One is a 2.1 A port. Even the box isn't labeled.

I'd hate you to wire the USB things up and they don;t work.


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