The normal wire size for a 50 amp circuit breaker is 6 AWG copper wire. If you are using aluminum wire, it will require a 4 gauge wire size.
Using the wrong wire size may affect the safety of your electrical system.
Wire sizing is one of the skill that differentiates real electricians from quacks. Armatures may use a 30 amp or 60 amp wire for loads that require a 50 amp wire size, this can cause electrical fire and safety hazards.
Heavy duty appliances such as kitchen ovens and dryers use a 50 amp circuit. It is therefore important to use the normal size wire for maximum safety.
You should also observe the National Electrical Code (NEC) 80% breaker rating rule to ensure safety.
Importance of using the correct size wire a 50 amp breaker
Using the correct wire size for the electrical circuit is important for the safety and proper functioning of the electrical system. Below are the importance:
Safety: A normal gauge wire will ensure the safety of your electrical circuit. Using the wrong size wire can lead to electrical fire, electrocution and other safety hazards.
Efficiency: A normal sized wire will ensure that the electrical system operates normally. If the wire is too small, it can lead to a voltage drop, a condition that reduces the performance of electrical equipment, leading to equipment failure, increased energy consumption and reduced lifespan.
Compliance: Using the correct size wire is also important for meeting the NEC code requirement. Electrical codes provide guideline for safety installation and use of electrical systems, and these codes specify the normal size wire for different applications.
Wire gauge chart
| AWG Number | Cross Sectional Area (mm”) | Ampacity | ohms/km (/km) | Usage |
| 18 | 0.82 | 14 | 20.95 | Low voltage lighting |
| 16 | 1.31 | 18 | 13.18 | Extension cords |
| 14 | 2.08 | 25 | 8.28 | Lighting fixtures |
| 12 | 3.31 | 30 | 5.21 | Kitchen appliances |
| 10 | 5.26 | 40 | 3.28 | Electric dryers |
| 8 | 8.37 | 55 | 2.06 | Electric ovens |
| 6 | 13.30 | 75 | 1.30 | Large electric heaters |
| 4 | 21.15 | 85 | 0.81 | Large furnace |
| 3 | 26.67 | 115 | 0.65 | Large commercial wiring |
| 2 | 33.63 | 130 | 0.51 | Car battery cable |
| 1 | 42.41 | 145 | 0.41 | Power distribution |
| 1/0 | 53.47 | 170 | 0.32 | Power distribution |
| 2/0 | 67.43 | 195 | 0.26 | Power distribution |
| 3/0 | 85.03 | 225 | 0.20 | Power distribution |
| 4/0 | 107.22 | 260 | 0.16 | Power distribution |
| 250 | 126.68 | 290 | 0.13 | Power distribution |
| 350 | 177.35 | 350 | 0.10 | Power distribution |
| 400 | 202.68 | 380 | 0.08 | Power distribution |
How to determine the right wire size for the 50 amp circuit
To determine the normal size wire for the 50 amp circuit, there are certain factors to consider. They include:
1. 80% NEC Rule
The NEC 80% role helps in selecting the normal awg wire that can handle 50 amps circuits. The rule states that you must have atleast 20% extra ampacity on top of the 50A ampacity to avoid overheating the wires.
Here is how to apply the rule.
Let’s assume you want to know the perfect size of wire that can carry 50 amps safely. All you will do is divide 50A by 80%.
That is: 50A/ 0.8 = 62.5A.
If you check the above wire size chart, you see that there is no 62.5A on the table. However, from 55A up to 75A uses 6 awg wire, and that’s the normal wire gauge for 50 amp breakers.
Note, in the American wire standard chart, you should always use a larger number and never a smaller one when choosing the wire size.
2. Account for voltage drop
Even if you are supplying currents to a 50 amp sub panel 100 feet away, the voltage loss must be taken care of.
The voltage drop rule states that in every 100 ft of wire, the voltage drops by 20%. And to get the same wattage at the sub-panel 100 feet away, you must boost the amps by 20%. This can be achieved by using bigger wires.
For example, since you already know that a 50A breaker requires a 6 gauge wire to work safely, how many gauge of wire will it need if you want to power an electrical device at a long distance, say 100 feet away?
The first thing is to boost the amps by 20%. That is 62.5A x1.2 = 75A.
Then check on the wire gauge table to see the normal gauge wire for 75 amp. A 75A circuit will require a 4 awg gauge wire.
So, the proper gauge wire for a sub panel located 100 feet away is 4 awg wire.
3. Type of conductor: Is it aluminum or copper wire
When choosing the right wire size for your breaker, it’s important to consider the type of conductor you’ll be using.
Copper and aluminum are the two most common cables used for wire, and they have different wire sizes for the same amperage ratings. For a 50-Amp circuit, a 6 AWG copper wire or 4 AWG aluminum wire is recommended.
While copper provides better conductivity, it can be more expensive than aluminum. However, aluminum wires are more prone to corrosion and require larger sizes to handle the same amperage. You should weigh their pros and cons and make your choice.
Frequently asked questions about 50-amp circuit breaker
Can 8 gauge wire handle 50 amps
No, an 8-gauge wire is not rated to handle 50 amps of current. According to the American Wire Gauge (AWG) standard, an 8-gauge wire is rated for a maximum current capacity of 40 amps.
To handle 50 amps, you will need a 6-gauge or larger. However, the exact wire size will depend on various factors, such as the length of the wire run, the type of insulation used, and the ambient temperature of the environment in which the wire is installed.
What Wire Size Do I Need for a 30 amp Circuit Breaker?
A 30 amp 240 volts breaker will require a 10 gauge copper conductor to perform. This wire can handle or ensure that the circuit carries the required load without overheating.
Note that the recommended wire size can change with an increase in wire length and the allowable voltage drop.
If the circuit is longer than 100 ft, you may need to use a larger wire size to compensate for the voltage drop.
Conclusion
A proper wire size is necessary for a safe electrical installation. Always ensure you are using the appropriate wire gauge.
A larger wire size is usually recommended since it won’t cause any problems except higher cost. Using smaller wire sizes is risky and usually leads to overload and damage to electrical appliances.
This article will help you determine the normal wire size you need for your 50 amp current. If you are still unsure about the 50 amp wire size, you can call an electrician for proper guidance.