Running electrical cable outside of your home can be a complex task that requires knowledge of electrical codes and safety practices. However, in some cases it may be necessary or desired to have exposed Romex cable on the exterior of your house. With proper precautions, this can be done safely.
When Exposed Romex May Be Allowed
The National Electrical Code (NEC) has strict rules about running Romex cable outdoors. Romex, which is an electrical cable with rubber insulation and a flexible plastic jacket, is intended for indoor use only. However, the NEC makes a few exceptions where exposed Romex is allowed:
- On the underside of eave overhangs, porches, or balconies
- To connect a garage or outbuilding to your main electrical panel
- For low-voltage landscape lighting circuits
In these cases, you must take precautions to protect the cable from damage.
Protecting Against Sunlight and Moisture
The main hazards to Romex outdoors are ultraviolet (UV) radiation from the sun and moisture. The jacket on Romex will degrade quickly when exposed to sunlight. Water can also seep into the insulation and cause shorts or corrosion.
To protect against these hazards:
- Use sunlight-resistant cable marked "WA" or "SR". This has UV-resistant insulation.
- Run cables on the underside or north side of overhangs to reduce sun exposure.
- Use cable staples every 4-6 feet to fasten the cable snugly.
- Caulk around cables where they enter the house to prevent water intrusion.
- Do not attach cables directly to wood surfaces. Use plastic standoff mounts to allow air circulation.
Following Electrical Code Requirements
Even where the NEC allows exposed Romex, you must follow code requirements:
- Cables must be at least 8 feet above ground level.
- Cables must be protected by a conduit or other cover where exposed to physical damage.
- Outdoor cables must be GFCI protected. Install GFCI outlets or breakers.
- Cables run on the exterior surface must remain under 30 feet in length.
Also check your local building codes for any additional restrictions on outdoor Romex use. Getting a permit and inspection for outdoor electrical work is recommended.
Hiring an Electrician
Because of the safety issues involved, it is best to have an experienced electrician handle any outdoor wiring. They can ensure it is done safely and according to code.
Some aspects that an electrician will handle include:
- Selecting the proper outdoor-rated cable for your needs.
- Routing cables in protected areas on eaves or siding.
- Installing GFCI protection and an external shutoff switch.
- Completing necessary permits and inspections.
Although a do-it-yourself project may seem simpler, the risks of improperly installed outdoor Romex are high. Hiring a pro ensures you can light up your outdoor space safely.
Maintaining and Inspecting the Cables
Once outdoor Romex is installed, be sure to periodically inspect it for any signs of damage or deterioration. Look for cracked/brittle insulation, moisture accumulation, and cable sagging. Damaged sections should be replaced immediately by an electrician.
Also have an electrician inspect all outdoor wiring during any major electrical upgrades. Proactive maintenance will keep your exterior cables in good shape for years of service.
With proper installation and care, exposed Romex can be run safely outside of your home in approved circumstances. But be sure to closely follow electrical codes, use sun/water resistant cable, and consider hiring a professional electrician to handle this type of specialized wiring work. Taking the right precautions will prevent hazards from outdoor Romex use.