Learning, Wiring,

How Far Can You Run 10/2 Wire (Length vs Resistance)

If you’re wondering how far you can thread a 10/2 wire in your wiring project without affecting amperage you are in the right place.

50 ft. or 15.25 meters at most. Running a 10/2 wire beyond 50 feet can reduce the amps and the overall power output of a 10/2 wire. As the wire length increases, so does the resistance that impedes a seamless flow of charge or electrons. As an electrician, I will teach you how far you should span a 10/2 wire in detail.

The farthest you can thread a 10/2 wire (i.e. two conjoined ten gauge wires with an additional ground wire) without appreciably affecting amperage is 50 ft. Running a 10/2 gauge beyond 50 ft. can tremendously extenuate or lower the amps rating of the wire. The length of the wire varies proportionally with resistance; so, as resistance increases the charge volume density reduces. Effectively, the current or amps diminishes.

I will go into more detail below.

10/2 Wires

10/2 wires are usually used to wire air conditioners which demand the use of specifically sized wires for efficacy. They (10/2 wires) are highly recommended for the AC units because they can handle the amps flowing in the circuits safely.

10/2 wires use two 10 gauge wires with a combined ampacity of 70 amps. The wire consists of one 10 gauge hot wire (black), one 10 gauge neutral wire (white), and one ground wire for safety precautions.

The ampacity of one copper 10 gauge wire is approximately 35 amps at 75 degrees Celsius. Implementing the 80 percent NEC rule, such a wire can be employed in a 28 amps circuit.

So, mathematically, 10/2 wires can contain 56 amps. In that vein, if your device, say an air conditioner, draws about 50 amps; then you can use a 10/2 wire to wire it.

However, in this guide, I will focus on how far you can span ten gauge wire without significantly affecting the amperage or any other functionality of the 10/2 wire.

Threading 10/2 Wire

The following are the properties that can be affected as the length of 10/2 wires, or any other wire gauge, are spanned:

Resistance & Wire Length

length against resistance graph

Resistance increases with length.

There is a direct relationship between the length a 10/2 wire must traverse and the amount of resistance the charge faces.

Essentially, as the 10/2 wire length increases the charge collision increases leading to an exponential increase in resistance to current flow. (1)

Amperage & Wire Length

The amp rating of a 10/2 wire can drop dramatically if it spans more distance.

As aforementioned, an increase in resistance will directly affect the flow of the electrical current. That’s because the electrons get prevented from flowing seamlessly through the wire.

Temperature & Wire Length

The table below lists the ampacity of various wire gauges at given lengths.

length of wire table

So, How Far Can You Span 10/2 Wire?

According to the AWG stipulations, a 10/2 wire can span 50 feet or 15.25 meters, and it can handle up to 28 amps.

Other uses of 10/2 gauge wire include speakers, home wiring, extension cords, and other electrical appliances whose amps ratings are in-between 20 and 30.


Are 10/2 and 10/3 wires interchangeable?

10/2 wires have two ten gauge wires and one ground wire while 10/3 wires have three ten gauge wires plus a ground wire.

You may use a 10/3 wire on a 10/2 run, excluding the third ten gauge wire (in a 10/3 wire). However, you cannot use 10/2 wires on a device that requires 10/3 wires (two hot, one neutral, and a ground).

Can one use a four-prong twist lock receptacle with a 10/2 wire?

Yes, you can.

However, you will be breaching the wiring code regulation that requires all the terminals of a connector that uses AC power to be wired accordingly. So, it is best to avoid such incidence as they can cause confusion and potentially electrical accidents. (2)

Take a look at some of our related articles below.

(1) collision – https://www.britannica.com/science/collision
(2) electrical accidents – https://www.grainger.com/know-how/safety/electrical-hazard-safety/advanced-electrical-maintenance/kh-3-most-common-causes-electrial-accidents

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About Sam Orlovsky

AvatarCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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