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What Size Wire Do I Need for a 60 Amp Sub Panel?

Written by Edwin Jones / Fact checked by Andrew Wright

what size wire do I need for a 60 amp sub panel

“What size wire do I need for a 60 amp sub panel?” is a common question because most sub panel setups fall within that amp load. Based on Table 310-16 of the NEC, a 6 AWG copper wire for the hot and neutral connections and a ground wire size of 8 AWG will do.

However, you need to consider the NEC’s 80% total load rule and must also take voltage drop into account if the main panel’s over 100 feet away from the service breaker box. A 4-gauge or even 3-gauge wire will work better.

Keep voltage drop under 5%, and don’t feel bad about the extra expense of oversizing wires, as it’s way better than under-sizing them.

Read on for a more detailed explanation.

Why a Larger Size is Arguably the More Suitable Wire Size for 60 Amp Sub Panel

First and foremost, I don’t recommend sizing at the minimum 6-gauge, especially if you’re planning to expand in the future. If that’s the case, you may also want to consider using fatter PVC conduits.

Using a 4 AWG wire bumps your ampacity to up to 85A at 75°C or 65A if we’re considering wire size aluminum.

4 AWG is the wire size for 60 amp 220V that most pros will recommend. After all, is there any serious harm in picking a bigger wire size for 60 amp breaker, as long as it’s still compatible with that ampacity?

Sure, the cables may become more costly, heavier, and less flexible, but do those downsides compare to the risks of electric fires and your appliances and gadgets failing?

Many property owners thank their past selves for making the decision to oversize, since they won’t have to take the wire out and install a new one. More importantly, this choice adheres to the safety recommendation that you shouldn’t let the breaker load exceed 80% of the service’s total ampacity.

Still, if you settle for the minimum 6 AWG wire for 60 amp breaker, you will still essentially conform to NEC guidelines. Some will even argue that your average wire size chart already factors in the 80% load rule.

But, I’ll always be able to counter that by saying you’re playing with fire, especially if you know that your wires stretch over 100 feet or more and you plan to do future expansions.

Accounting for Voltage Drop

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We’re talking about sub panels here. That means you’re likely working with a box that’s some distance from the main panel. In most cases, residential runs range from 100 feet to a little over 200 feet.

These only mean one thing: We can’t ignore voltage drop when calculating 60 amp wire size for sub panels.

Voltage drop begins to become significant once your conductor is over 100 feet because that often means a 20% drop.

That’s not always a static figure, mind you, since it’s also affected by other factors such as wire count and material.

However, we can’t deny that most electricians agree that runs over 100 feet are when voltage drop percentages become risky (i.e. begins to exceed the 5% safety threshold).

Assuming you won’t be using tools like a welder that may overload the circuit, we arrive at the following recommendations for setups of 150 feet or 200 feet at 220V/240V. These recommendations make the setup future proof as well.

  • 3 AWG copper wire is the 60 amp sub panel wire size if the main’s 150 feet away and assuming the voltage drop reaches as high as 30%. That’s because if we factor in the 80% rule and the 30% voltage drop, such a setup will require a wire that can handle 97.5A in reality.
  • If the main panel’s over 200 feet away, you can use a 4 AWG copper or 3 AWG aluminum or copper. However, since we’re already dealing with plenty of voltage drop in this case, a 2 AWG aluminum wire or 2-2-2-4 aluminum mobile home feeder, to be exact, may be the best option.

That’s still a suitable 60 amp service wire size and is less expensive than a copper run.

Don’t Forget About the Appliances or Tools You’re Going to Use

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If you’re actually building a large workshop or a garage for your woodworking projects, for instance, you may need to consider the fact that most garage breaker boxes range between 50 to 100 amps.

If you think you’ll end up taxing your circuits too much, then you may need to look past the wire gauge for 60 amp and at the wire size for a breaker panel with a higher ampacity instead.

Lastly, don’t expect that you should limit your option to 60 amps when planning your sub panel. You may actually be able to make your setup work with breakers with far lower ampacities if you know which CBs and wires to use.

The point is, don’t close your doors to professional advice from an electrician, so you’ll end up with the most ideal setup.

Frequently Asked Questions

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What do I need to know about wire sizes?

The wire’s size determines the amount of current that can flow through it. The general rule of thumb is larger sizes mean less resistance. The wire’s diameter is indirectly proportional to its wire number.

For example, 2 AWG wires are bigger in diameter than their 4 AWG counterparts, and so on.

Why is the right wire size important?

Using smaller-than-required wires often leads to higher resistance in the circuit, which translates to more heat.

This ups the risk of overloads, appliance failure, and electrical fires. Moreover, there are specific wire sizes that can fit into a certain breaker’s receptacle.

Can 8, 6, 10 gauge wire handle 60 amps?

Only the 6-gauge wire will be able to safely handle 60 amps, and that’s just the minimum for the said ampacity. 10 or 8-gauge wires will work better for smaller ampacities of 30A and 40A, respectively.

Conclusion

I hope you’ve gotten a satisfactory answer to “What size wire do I need for a 60 amp sub panel?” from the inputs I’ve shared here. 6, 4, 3, or even 2 AWG wires will work for 60A panels, and that’s with voltage drop and long-term improvements factored in.

If you’re having doubts, consult an electrician. More importantly, be sure you don’t use the wrong wire size, specifically, a smaller wire than necessary.

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