How to Use Outdoor Romex

Outdoor ROMEX® -- a brand of nonmetallic electrical cable meant to be installed underground -- is protected by a different exterior insulation material than indoor ROMEX®.
Protect outdoor ROMEX® in electrical conduit where it is not underground.
Indoor ROMEX®’s outer sheath consists of moisture-resistant, flame-retardant, nonmetallic material surrounding electrical wires insulated with thermoplastic high heat nylon. Outdoor ROMEX® encases the nylon insulation in flexible polyvinyl chloride (PVC) insulation with a sunlight-resistant PVC outer jacket. The way you use outdoor ROMEX® is very specific. .

Step 1

Bury the outdoor ROMEX® in a trench in the ground when running electricity from one location to another. Check with your city or municipality for the required burial depth. These depths vary between 18 and 24 inches.

Step 2

Lay the outdoor ROMEX® directly in the trench without conduit and cover it with the dirt you removed from your trench. The insulation material of the cable protects the encased electrical wires from moisture.

Step 3

Encase the outdoor ROMEX® in conduit where it is not underground. Running the cable from the ground and up a wall requires the protection of either metal or PVC conduit. Even though the cable is both moisture and sunlight resistant, the cable is susceptible to damage from animals or objects hitting the cable.

About the Author

Cecilia Harsch has been writing professionally since 2009. She writes mainly home improvement, health and travel articles for various online publications. She has several years of experience in the home-improvement industry, focusing on gardening, and a background in group exercise instruction. Harsch received her Certified Nurses Assistant license in 2004. She attended Tarrant County College and studied English composition.