How Many Amps Can a 18 Gauge Wire Handle (The Truth!)

How Many Amps Can a 18 Gauge Wire Handle

Have you ever asked yourself or your friend how many Amps a 18 gauge wire can handle? Well, you are at the perfect place to find the answer to such a question.

When it comes to low power requirements in small appliances, that is usually where you will find 18-gauge wiring.

It’s not large enough to handle most of your home necessities but it can handle some of the smaller things that you may have just assumed that 14-gauge wire was used for.

So, how many amps can a 18 gauge wire handle? A 18 gauge wire can handle between 3 and 15 amps without a problem depending on the conditions. “Conditions” is the keyword, as the length of the wire, insulation, and power all make a difference in what it can handle.

It’s not as if an 18-gauge wire is significantly used in most residential homes, as they are rated for 15 and 20 amps.

While 15 amps are the maximum load an 18-gauge wire can handle under completely optimal conditions, it doesn’t mean that it should be used, depending on the application. 

What Does 18 AWG Mean?

AWG stands for American Wire Gauge and 18 is simply the diameter of the wire under the AWG rating system.

The AWG has been around since 1857 so apparently, they found something pretty useful for it to have survived for a century and a half. 

But AWG tells you more than just the diameter of the wire that you’re using. AWG also defines the resistance per foot for every gauge type, including a size 18 wire.

For instance, according to the AWG standards, 18-gauge wire has a resistance (represented in Ohms) of 6.4 per foot. 

That also comes into play when you are attempting to figure out what the voltage drop will be over a specific distance with a specific load and a specific wire diameter.

To determine the voltage drop for an 18-gauge wire, for example, you will determine the resistance at, let’s say, 500’ and multiply that by the voltage. 

However, the overall formula is affected by the load as well. So there is a lot more that goes into the wiring in your home, in the power lines that run down your street, in the factory downtown, and the giant manufacturing industries across the country. 

Read also: How Many Amps Can a 8 Gauge Wire Handle (AMPACITY CHARTS!)

Different Types of 18-Gauge Wire

We aren’t referring to whether or not your 18-gauge wire is made of something other than copper, but rather, the different types of size 18 wire in terms of the insulative properties and how hot they get under a certain load. 

In its bare naked form, you will generally find that 18-gauge wire is used as a grounding wire. It doesn’t matter what the application is, if you see it without insulation, there’s a large chance that it’s being used to ground, which means that it will channel the current into the ground in case something goes wrong. 

Then there are the ULs. These would be the next step up from just bare 18-gauge wire. The insulation is neither thick nor heavy and it’s rated in voltage.

For instance, UL1015, an 18-gauge wire, can handle 600V up to a temperature rating of 105°C. 

Half of that, UL1007, can handle 300V and has the exact, same temperature rating.

Then there are Teflon insulated 18-gauge wires and they are generally capable of dealing with temperatures in the extreme, up to 200°C.

However, the copper portion of the wire doesn’t undergo this stress alone, as it is aided by strands of silver wiring wrapped around it.

Nylon coatings are nowhere near as highly rated in terms of temperature and they are designed for different situations. 

The nylon size 18 wires are coated in PVC and are cheaper than the Teflon, silver strand version because when you remove silver from the equation, things get a whole lot more affordable. 

Of course, this is just a small example of the hundreds of applications for 18-gauge wire and what they are generally insulated with.

You would be surprised at the number of small applications for this thin little wire in tiny devices and appliances. 

What is Size 18 Wire Used For?

As alluded to above, there are a lot more uses for 18-gauge wire than you might think. However, it’s mostly relegated to small devices and it exists within the bubble of that device.

For instance, there isn’t going to be any 18-gauge wire running through your home.

But, you will find it in the power cord wires for small lamps, fans, alarm clocks, mood lights, stereo equipment, small cameras, locks, and other devices that are relatively small and don’t require much power to use. 

As mentioned above, its also used as a grounding wire in some applications. To put the smallness of this wire into perspective, its diameter is a whopping .0403 inches.

That’s a pretty small wire so you won’t see it in standard lighting. 

However, if you love those little desk fans and tiny lamps that don’t take up a lot of space in your work area, those kinds of things are full of 18-gauge wire.

Read also: How Many Amps Can a 4 Gauge Wire Handle (Ampacy Chart!)

Is Size 18 Wire Common?

Despite everything that we just said, size 18 wire isn’t considered to be a common wire. The common wires are 2, 6, 8, 10, 12, and 14 AWG. 

Those are common wires simply because of what they are used for. 14 and 12 gauge wiring is something that you will find in residential homes and commercial buildings.

Those two are just about the only two you will find in those applications.

Everything else is just an add-on. For example, 6, 8, and 10 gauge wiring are typically used in many of your larger, household appliances, such as washing machines, dryers, refrigerators, dishwashers, A/C units, and window units. 

So while 18-gauge wiring isn’t going to be powering your biggest appliances and devices, it still has a place in the household. 

Can 18-gauge Wire Handle 120 Volts?

While there are theoretical applications in which size 18 wire can handle 120 volts, it isn’t a part of what this size wire would usually handle.

For the most part, 18-gauge wire isn’t going to handle anything heavier than 47 volts. 

In fact, an 18-gauge wire wouldn’t even be connected to a fuse that would have that level of current allowance on it.

The danger in running current through a size 18 wire that is more than it could handle is creating a fire hazard. 

It would heat the 18-gauge wire enough to possibly melt the insulation, exposing the wiring and putting you or someone else at risk of being electrocuted.

It doesn’t matter how many volts you put through a wire of this size, because it will conduct it. 

The point is, how many volts could you put through it before the wire itself melts down to slag? When it comes to size 18 wire, you shouldn’t exceed the current that is supposed to be applied to it in a given situation or you risk melting the insulation and perhaps the wire itself. 

Final Thoughts

In normal circumstances and operating under safe conditions, a size 18 wire can handle anywhere between 3 and 15 amps, depending on what it is rated for, in terms of the insulation type.

While you won’t find 18-gauge wire all over the place, especially in the home, you will find that it is the typical wiring used in small devices that are considered “low-power” devices, such as small lamps and personal desk fans. 



Jeff is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Reatta. Jeff has been creating written and video content about transportation, automotive, electric cars, future vehicles as well as new, used for more than 18 years. Jeff is based in Boulder, Colorado.

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