As an electrician or diy, it is important that you master the basics of wire sizing. This is to ensure maximum protection and safety of electrical appliances.

A 60 amp breaker will require a 4 awg size wire for maximum protection. Using the wrong wire size, say 6 awg, may lead to poor conduction and electrical hazards.

**Contents**hide

**What is an electrical wire size or gauge?**

An electrical wire gauge is a measurement of the wire diameter, to determine the amount of electricity it can safely carry without damage. It also determines the weight of the wire and its resistance power.

**American Wire Gauge System**

This is the standard method used to measure wire sizes by assigning AWG numbers to them. The higher the awg numbers, the smaller the wire size and its ampacity (amount of current it can carry).

Lower awg numbers indicate a larger wire size and this carries more current and also has more resistant power.

There are a total of 40 different wire sizes and gauges ranging from 0.013 mm^{2} to 107.22 mm^{2. }

**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 |

**Steps to determine the 60 amp wire size.**

Although some people use 6-gauge wire for 60 amp wiring, it is never the right wire gauge. The correct wire size for the 60 amp breaker is the 4-gauge wire.

So when choosing a wire size for any breaker, always consider the ampacity of the wire and its ability to withstand high voltage without melting.

Also, follow the NEC guidelines for selecting a wire size for your breaker. The rules include:

- 80% breaker rating rule
- Account for voltage drop.

**80% breaker rating rule**

This rule is important in wire sizing as it guarantees electrical safety. Let’s assume we want to determine the wire size for 60 amp circuits.

The size of the wire required to carry 60 amp 220v is 80% of the wire size you need.

This implies that for you to wire a 60A circuit breaker, you must need a wire that can handle a minimum of 75 amp. Below is how to do the calculation.

60 amps **÷ **0.8 or 80% = 75 amps.

If you check from the wire gauge chart above, you can see that the correct wire size that can handle 75A is 4 awg wire.

The wire can carry up to 85 amp, meaning that it can handle 75 amp.

This is what those homeowners that use a 6 gauge wire size on a 60 amp don’t understand. The 6 awg wire can only handle 65 A.

### Account for voltage drop.

This law is not for short distance wiring, it is for lengthy wiring of about 100 feet and above. If the length of the wire connecting your 60 amp breaker is up to 100 or 150 feet, consider applying this nec code.

This is to make sure you don’t use a 4 wire gauge when you suppose to use a 3 awg wire.

Here is the first rule:

**For every 100 feet of wire, the voltage drops by 20%.**

The actual percentage loss may vary depending on the type of wire used such as aluminum wire, copper wire or steel, but you must observe the rule.

This implies that in every 100 feet of wire, we should increase the amps by 20% to maintain the same power output.

Here is the formula: **Power (Watts) = Current (Amps) × Voltage (Volts)**

Let us use one example so that you will understand how to use the voltage drop law to determine the wire size.

Example:

**What is the 60 amp wire size when a sub panel is 150 feet away?**

Now, we already know from the 80% breaker rating rule that a 60 A breaker will require a wire that can handle at least 75 amp, we should now apply the voltage drop law to see the outcome.

According to the law, the voltage drops by 20% in every 100 feet of wire. So in 150 ft, the loss should be 30%.

This implies that we should increase the amps by 30%. To achieve this, we should multiply 75 amps by 1.3.

75 amps × 1.3 = **97.5 **amps

So to wire a 60 amps breaker with a sub-panel 150 feet away, you will need a wire that can withstand 97.5 amps.

To achieve this, you make use of a 3 awg wire.

A 3 gauge wire can handle a 60 amp breaker with a sub panel 150 ft away.

You can watch this video for clarification on how to size circuit breaker wires.

### copper vs aluminum wire, which one is suitable for a 60 amp circuit?

Copper and aluminum are good conductors of electricity but used for different purposes.

Aluminum is used in feeding the main service panel, sub-panels service poles. It is not used in branch circuit wiring.

Aluminum can expand and contract with a change in temperature, it can also oxidize over time, leading to loose connections and fire hazards.

Copper wire is strong, reliable and can withstand any stress. It is suitable for a 60 amp breaker.

### Conclusion

For homeowners and diy with little experience in electrical wiring, determining the right wire size for your breaker can be hard, but this guide will surely put you through.

Make sure you follow the NEC codes, which include the 80% breaker rating rule, and the account for voltage loss.

Hope this article helps.

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