Yes. You can use NM-B (Romex) in a garage, but only when it is properly protected from physical damage and moisture, and the space qualifies as a dry interior environment.

For exposed runs—especially below 7–8 feet—MC cable or conduit-based wiring methods are safer

This means running it inside walls or behind drywall. You can also run NM-B Romex in the conduit, though, if the application calls for a conduit, alternatives can be used.

Garages are generally considered dry locations suitable for NM-B wiring, but they are also higher-risk environments than typical interior spaces. Because NM-B has no built-in mechanical protection, its use in garages is limited by the manner and location of its installation. For exposed runs, especially below 7–8 feet, MC cable or conduit-based wiring methods are safer. Let's create a roadmap of how NM-B (Romex) is used in garages.

When NM-B Is Appropriate in a Garage

NM-B may be used in a garage only when all of the following conditions are met:

• The garage qualifies as a dry location

• The cable is not subject to physical damage

• The cable is concealed or properly protected

• The installation complies with local AHJ requirements

Typical approved installations include:

Inside Walls or Ceilings (Concealed)

NM-B is permitted when installed inside finished walls, floors, or ceilings, such as behind drywall or plywood. Finished surfaces already provide both mechanical protection and the required thermal barrier, which is enough for keeping the M-B cable secure.

Once concealed, the NM-B wiring is treated the same as wiring in other interior areas of the home. There is no difference between using NM-B Romex in a finished, dry garage, and literally elsewhere in the house.

Inside Conduit (Protected Surface Runs)

NM-B may be run inside PVC or metal conduit on concrete walls. This adds protection against impact, abrasion, or pests. For longer runs, conduit fill often becomes an issue, making THHN/THWN-2 conductors a more practical choice than NM-B. If you need a conduit in your basement, consider running THHN/THWN-2 instead of NM-B.

When NM-B Is Not Appropriate in a Garage

NM-B should not be used in the following situations:

Below 7–8 Feet from the Floor

Exposed NM-B below this height is commonly considered subject to physical damage from vehicles, tools, ladders, or stored equipment. In these areas, protection or an alternative wiring method is required.

In some jurisdictions, however, exposed NM-B is allowed above normal reach, such as along ceiling joists or rafters, if it is properly secured, follows framing members, and remains clearly out of the way.

Many inspectors apply a practical threshold of about 7–8 feet, although this is not a fixed NEC rule and varies by AHJ. The final decision is likely to depend on the inspector, not the formal rules found in the NEC.

Outdoor or Underground Runs

NM-B is never permitted outdoors, even when installed in conduit, and it is not approved for underground installations. Use UF-B or THHN/THWN-2 in conduit instead.

Detached Garages

Detached garages often fall under stricter local rules, especially for feeders and grounding. They are separated spaces that are not considered a part of the interior area in the house. Aside from the fact that detached garages need separate grounding and bonding, they also have feeders and branch circuits that pass through wet locations.

NM-B is not permitted beyond fully finished interior spaces.

What Does the National Electrical Code Say?

NEC 334.15(B) requires NM cable to be protected where it is subject to physical damage.

NEC 334.12(B)(4) prohibits NM-B in damp or wet locations.

While garages are typically considered dry, exposed concrete walls, condensation, or humidity may cause an AHJ to classify the space as damp, making NM-B unacceptable.

Using NM-B With Protection

In limited cases, NM-B may be installed in unfinished garages only if protected, using methods such as:

• Guard strips or running boards

• Short conduit sleeves where impact or abrasion is likely

• Approved raceways

Once extensive protection is required, many electricians choose MC cable or conduit wiring instead. These options are more cost-effective and better suited for inspection.

A Case for Alternatives

Although NM-B is allowed in garages under specific conditions, many electricians avoid it due to the ambiguity of what qualifies as subject to physical damage. Garages are multi-tasking places with cars moving, which creates constant vibration. They also often serve as storage. Armoured or conduit-based wiring methods are more predictable for wiring a place at constant risk of physical impact.

MC Cable

MC cable has built-in mechanical protection, which makes this a common option for exposed runs in unfinished garages. It remains compliant even if the garage is never finished.

EMT Conduit with THHN/THWN-2

EMT offers excellent mechanical protection and a clean appearance. It is often used in low wall runs, or anywhere frequent contact is expected. If the garage gets busy with constant movement and vibration, this is the best option.

UF-B Cable

UF-B is used for outdoor or underground runs to detached garages. It is rated for wet locations and direct burial.

Garage Wiring: Approach by Scenario

1) Finished Garage (Dry, Enclosed)

NM-B behind drywall

2) Unfinished Garage (Dry, Exposed Studs)

MC Cable

Alternative: NM-B with conduit or guard strips (less common).

3) Damp or Moisture-Prone Garage

Jacketed MC or THHN/THWN-2 in conduit

NM-B is not permitted.

4) High-Traffic or Impact-Prone Areas

EMT Conduit with THHN/THWN-2

5) Garage to Be Finished Later

MC Cable now → NM-B later (if rewired)

Key Considerations

• "Subject to physical damage” is enforced differently across jurisdictions and is open to interpretation by the local inspector.

• Exposed NM-B may pass in one garage and fail in another. The success depends on the unique characteristics of your particular garage: height of installation, routing, and the extent of physical damage the wiring is exposed to.

• Installation quality is critical. Regardless of the task, cables must be secured and follow the contours of the building surfaces. If you are running NM-B, avoid sharp metal edges such as garage-door hardware.

At Nassau National Cable, you can find NM-B copper building wire for your dry, finished garage at excellent prices. If you discover that NM-B Romex does not fit in your garage, we also offer MC metal-clad cables and THHN THWN-2.