Wire Size for a 60-Amp Sub-Panel: 2026 NEC Guide

A 60-amp sub-panel feeder requires 6 AWG copper or 4 AWG aluminum when the terminals are rated 75 degrees, which is standard on modern panels. Many electricians still pull 4 AWG copper for extra margin or for long runs, and that is fine, but 6 AWG copper is the true NEC minimum. The bigger story with a sub-panel is the four-wire feeder and the grounding rules, which is where most DIY installs go wrong. This guide covers the wire, the cable, grounding, and distance for a garage, workshop, or addition.

60-Amp Sub-Panel Wire Size Quick Reference

6 AWG Copper Is the NEC Minimum, 4 AWG Is the Safe Habit

NEC Table 310.16 rates 6 AWG copper at 65 amps in the 75-degree column, which exceeds the 60-amp feeder rating, so 6 AWG copper is code-compliant for a 60-amp sub-panel when the breaker lugs and panel terminals are listed for 75 degrees, and virtually all modern equipment is. You will still hear electricians insist on 4 AWG copper for a 60-amp feeder, and there are good reasons: it follows the older 60-degree rating where 6 AWG is only 55 amps, it adds voltage-drop margin on longer runs, and it leaves room to upgrade the sub-panel to a 70-amp feeder later. So the practical answer is that 6 AWG copper is the minimum that passes inspection, while 4 AWG copper is the choice many pros default to. For aluminum, 4 AWG is the 75-degree minimum at 65 amps, and 2 AWG aluminum is the popular real-world pick for the same headroom reasons.

The Four-Wire Feeder Rule

A sub-panel is not a main panel, and the difference matters for safety. A 60-amp sub-panel feeder must run four conductors: two hot legs, a neutral, and a separate equipment ground. Inside the sub-panel, the neutral bar must be isolated from the metal enclosure, and the ground bar must be bonded to the enclosure, the two are kept separate. This is the opposite of the main service panel, where neutral and ground are bonded together at one point. The reason is that bonding neutral and ground at a sub-panel would put normal neutral current onto the ground path and the metal enclosure, energizing equipment chassis under load. If your sub-panel came with a green bonding screw or strap installed, you remove it for a sub-panel application. This single rule is the most common failure on a DIY sub-panel inspection.

Cable Choices: SER, NM-B, and Conduit

For an interior feeder, SER cable is the usual choice, a 6/3 SER for copper carries two hots, a neutral, and a ground in a single jacketed run. SER is rated for service-entrance and feeder use and is easier to pull than four individual conductors. NM-B is also acceptable indoors but is bulkier at this size and is limited to its 60-degree ampacity, which pushes copper to 4 AWG, so SER or conduit is generally preferred. For a run to a detached garage or shed, or any exterior or underground portion, you cannot use interior cable, you pull individual THWN-2 conductors in conduit or use direct-burial-rated cable such as USE-2. Underground conduit to a separate building must be buried at the NEC 300.5 depth, typically 18 inches for PVC conduit, and the trench should avoid sharp rocks against the conduit.

Grounding a Sub-Panel in a Detached Building

If the 60-amp sub-panel is in the same building as the main panel, you simply run the four-wire feeder and keep neutral and ground separate. If the sub-panel feeds a detached structure such as a garage, barn, or shop, NEC 250.32 requires a grounding electrode at that structure, usually one or two ground rods, or a connection to a qualifying electrode such as a concrete-encased Ufer ground. Modern code still requires the four-wire feeder to the detached building and the neutral remains isolated there, while the local ground rods bond the sub-panel ground system to earth at that location. Skipping the ground rods at a detached building is a frequent oversight. The grounding-electrode conductor to the rods for a 60-amp feeder is typically 6 AWG copper, and a single rod is acceptable only if it tests under 25 ohms, otherwise a second rod is required.

Voltage Drop on a 60-Amp Feeder

Sub-panels often sit a long way from the main panel, in a garage across the yard or at the far end of a basement, so voltage drop deserves a look. On a 240-volt 60-amp feeder, 6 AWG copper reaches the 3 percent voltage-drop guideline at about 65 feet. Stepping up to 4 AWG copper extends that to roughly 100 feet, and 2 AWG to about 160 feet. This is the second strong reason many electricians default to 4 AWG copper on a 60-amp feeder, it covers both the conservative ampacity habit and a comfortable run length in one choice. Aluminum at 4 AWG hits 3 percent at around 65 feet, so for longer aluminum runs 2 AWG or 1 AWG is the move. Remember the feeder carries the whole sub-panel load, so under-voltage here drags down every circuit downstream.

Sizing the Breaker and Planning the Load

The 60-amp feeder is protected by a 60-amp double-pole breaker in the main panel, sized to the feeder conductor. A 60-amp sub-panel comfortably supports a garage or workshop with lighting, several 120-volt receptacle circuits, a 240-volt outlet for a welder or compressor, and an EV charger if the loads are managed. You size the feeder with a load calculation, not by counting breakers, because a sub-panel can physically hold more breakers than the feeder can supply, the breakers protect each branch circuit while the 60-amp feeder limits the total. If your plan keeps pushing past 60 amps, it is often worth jumping to a 100-amp sub-panel and pulling 3 AWG copper or 1/0 aluminum instead, since the labor to dig a trench or fish a wall is the same either way.

Electrical work carries safety and legal risk. Verify any calculation with a licensed electrician familiar with your local code amendments before performing work. This article references NEC 2023; many jurisdictions still operate under NEC 2017 or 2020 or have local amendments, so always confirm with your local AHJ.

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Data sources: NEC 2023 (NFPA 70) Table 310.16, 240.4(D), 310.12, and Article 250; NFPA 70 Handbook 2023; manufacturer termination ratings; r/electricians field reports. Written by Munir Afridi, VoltFlow editorial team.