30 amp wire size – Gauge, Length & Voltage

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30 amp wire size

What wire gauge, length, and voltage are recommended for a 30-amp service?

You should consider various factors if you want to install a new circuit or upgrade a new one. For instance, consider the size of the wire, the electrical appliances you want to power, and the distance. 

A kitchen oven and dryer may not consume the same power as a bulb. As such, the wire gauges for the two purposes will be different. Additionally, if the length of the wire is beyond 100 feet, you may experience a voltage drop. A higher gauge wire would be best to deal with the extra current.

Key Takeaways

  • The NEC recommends at least a 10 gauge wire for 30-amp connections
  • An 8 gauge wire is a perfect pick for a 30 amp service to account for the 80% NEC rule
  • You can pick a gauge higher to account for voltage drop when the connection is a distance away

So, what’s the proper length, gauge, and voltage for a 30 amps connection? 

Keep reading to find out. 

How Far Can You Run a 10 Gauge Wire on a 30 Amp Circuit?

You should check the AWG wire size chart to determine the ideal wire gauge for a connection. It’ll help you identify wire gauges with 30 amps and above. 

Your choice of wire should support the load you want to run it. 

According to the AWG size wire chart, a 10 gauge wire is recommended for a 30 amp connection. The wire size can safely handle the load offered by a 30 amp service. 

Is choosing a 10  gauge wire a mistake that most technicians and homeowners make? 

Although a 10 size wire has a 30 amp ampacity, there may be a limitation. According to the National Electric Code (NEC), the maximum load for a circuit should be 80% of the circuit rating for the wire ampacity. 

When you’re getting the right size for a 30 amp circuit, you need to consider the 80% NEC requirement. 

If you try to account for the requirement, you realize that a 10 gauge wire may not be adequate for 20 amp. You may have to go for the next size, the 8 gauge wire. 

Additionally, a 10 gauge wire may be adequate for a 30 amp service 10 feet away as you may not have to account for the 3% voltage drop. If the 30 amp service is 100 feet away, you require a wire gauge that can handle 45 amps. Therefore, you may use an eight-gauge wire. 

If the 30 amp sub panel is 200 feet away, you need a wire that can handle 52.5 amps. Therefore, you may go for a 6 gauge wire with 65A ampacity. 

Related: How to Wire GFCI Outlet? Diagram & Step-By-Step Instructions

Will a 12-2 Wire Carry 30 Amps?

Knowing the correct wire gauge for a particular purpose is vital. It helps you prevent adverse consequences such as a fire or damage to your electrical appliances.  For instance, using an 8-gauge wire to carry 50 amps may cause it to overheat and melt the insulation, leading to a fire. 

So, is a 12-2 gauge ideal for 30 amps?

You should consult the NEC manual to determine how many amps a particular wire size can handle. A professional technician can also advise you accordingly. 

Generally, a 12 gauge wire is ideal for carrying up to 20 amps. However, capacity depends on various factors such as distance and the type of electrical appliances. 

For example, if you want to power a 20 amps electrical device 150 feet away, you may have to upgrade the wire to a higher gauge. 

A 12-2 wire gauge may power light kitchen appliances such as refrigerators and hot water heaters

Related: Outlet Height From Floor – A Detailed Guide

What Size Romex Do I Need for 30 Amps?

A 30 amp breaker in your home can handle substantial current before it can trip the circuit. Getting the correct wire gauge would be best to avoid overheating and melting. 

According to the American Wire Gauge (AWG) standard for wire sizes, a 10-gauge wire is a minimum for a 30 amp circuit breaker. A wire size larger than 10 would pose safety risks, including fire. 

But using a gauge lower than 10 is recommended. 

But what size Romex should you use for 30 amps?

The Romex size also depends on the amperage required and the wire size for the electrical appliances. 

The following is a table of different wire sizes, amperage, and the appliances you can use them on. 

Wire Gauge AMPS TYPE of Wire
1/0 Gauge 150 Amps Feeder wire and service entrance
3 Gauge 100 Amps Feeder and service entrance wire 
3/0 Gauge 200 Amps Service entrance
14 Gauge 15 Amps Receptacle circuits and general lighting wire
6 Gauge 55 Amps Large appliances and feeder wire
8 Gauge 40 Amps Feeder and large appliance wire
10 Gauge 30 Amps Dryers, air conditioning, and appliances, 
12 Gauge 20 Amps Appliance, bathroom, and laundry circuits

Can I Use a 12 Gauge Wire on a 30 Amp Circuit?

As mentioned earlier, a 10 gauge wire can carry a 30 amps load. Even this may have limitations if the distance increases. If the electrical appliance you want to power is 150 feet away, it’d be best to go one gauge higher and use an 8 size wire. 

This helps account for the 20% voltage drop and reduces risks such as damage to your electrical appliances.  

Therefore, you shouldn’t use a 12 gauge wire on a 30 amp service. Doing so increases the chances of overheating as the wire struggles to carry the current. This may lead to the insulation’s melting, increasing the fire risk. 

Wire Size for 30 Amp 240 Volt Circuit 

Does the wire gauge change depending on the voltage?

The choice of wire gauge isn’t relevant to voltage. As such, it’s possible to get the same wire with 120V 30 amp and 240V 30 amp.  Although the wire size doesn’t change, the wattage that the circuit can offer does change. 

For instance,

  • You may get 3,300W wattage with a 110v 30 amp wire gauge.
  • 240V 30 amp wire size delivers 7,200W wattage.;

Additionally, it would be best to account for the 80% NEC rule. Your choice of wire gauge should have at least 37.5 amps. A 10 gauge wire only has 35A ampacity. Thus, consider going for an 8 gauge which can comfortably handle up to 50 amps. 

30 Amp Wire Size 100 Feet

If you want to power an electric device a long distance using a copper or aluminum 30 amp wire, you’ll experience a voltage drop. If the distance is just 10 feet away, the voltage loss is about 3%, which you don’t have to account for. 

If the electrical appliance is 50, 100, or 150 feet away, you must increase the amperage to account for the voltage drop.

NEC recommends increasing the amps by 20% for every 100 feet. 

For example, for a 30 amp sub panel 100 feet away, you should get a wire that can handle 45 amps. Thus, an 8-gauge wire may be ideal. If the distance is 200 feet away, you need a wire that can carry 52.5 amps. A 6 gauge wire would be the best for the purpose. 

30 amps Distance Wire Size (Copper)
  100 ft 8 AWG
  150 ft 8 AWG
  200 ft 6 AWG

Which Is the Ideal Wire Size for 30 Amp?

Getting the correct wire size is vital for safety purposes. Using the wrong wire may lead to overheating and melting the insulation, leading to a fire. When choosing the correct wire gauge, consider various factors, including distance and the electrical appliances you want to power.

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