national electric codes

National Electric Codes for Outdoor Wiring

With warm weather rounding the corner, we’re preparing to be outside as much as we can after the snow, wind, and rain. And despite soaking up the sun, there’ll also be electricity running outdoors as well. The National Electrical Code (NEC) has just as many requirements for outdoor circuits and equipment as they do for what’s indoors. The major safety concerns with outdoor wiring are protecting them from moisture, corrosion, physical damage, and underground burial.

Most outdoor code requirements have to do with outdoor power receptacles and lighting fixtures, as well as with running wiring above and below ground. Where the official Code requirements call for “listed” equipment, it means that the products used must be listed for the application by an approved testing agency.

Outdoor Receptacles

  • GFCI (ground-fault circuit-interrupter) protection is required for all outdoor receptacles, however there are exceptions for snow-melting or deicing equipment.
  • Homes must have at least one outdoor receptacle at the front and rear of the house. They must be accessible from the ground and no more than 6 1/2 feet above ground level.
  • Attached decks and balconies with interior access (such as from a deck into the kitchen) must have a receptacle no more than 6 1/2 feet above the deck, balcony, or patio. It’s generally recommended that homes should have a receptacle at each side of a deck or balcony that’s accessible from the ground.
  • Receptacles in potentially damp locations (such as a covered porch) must be weather-resistant and have a weatherproof cover.
  • Receptacles in wet locations (those that are exposed to weather) must be weather-resistant and have a weatherproof “in-use” cover.

Outdoor Lighting

  • Light fixtures in wet or exposed areas must be listed for use in wet locations.
  • Light fixtures in damp areas (those protected by an overhanging eave or roof) must be listed for damp locations.
  • Surface-mounted electrical boxes must be weatherproof.
  • Exterior light fixtures don’t require GFCI protection.
  • Low-voltage lighting systems must be listed by an approved testing agency as an entire system or assembled from individual components that are listed.
  • Transformers for low-voltage lighting must be readily accessible.

Outdoor Wiring

  • Exposed or buried wiring must be listed for its application. (Type UF cable is the most commonly used nonmetallic cable for residential outdoor wiring runs.)
  • UF cable can be direct buried (without conduit) with a minimum of 24 inches of cover.
  • Wiring buried inside rigid metal (RMC) or intermediate metal (IMC) conduit must have at least 6 inches of ground cover; wiring in PVC conduit must have at least 18 inches of cover.
  • Backfill surrounding conduit or cables must be smooth granular material without rocks.
  • Low-voltage (no more than 30 volts) wiring must be buried at least 6 inches deep.
  • Buried wiring runs that transition from underground to above ground must be protected in conduit from the required cover depth or 18 inches to its termination point above ground, or at least 8 feet above grade.

A Few Notes on Pools, Hot Tubs, and Spas

  • A permanent swimming pool must have access to an electrical receptacle no closer than 6 feet and no further than 20 feet from the closest edge of the pool. The receptacle must be no higher than 6 1/2 feet above the pool deck. The receptacle must have GFCI protection.
  • Receptacles used to power pump systems on pools and spas must be no closer than 10 feet from the inside walls of a permanent pool, spa, or hot tub if they are not-GFCI protected, and no closer than 6 feet from the inside walls of a permanent pool or spa if they are GFCI protected. These receptacles must be single receptacles that can serve no other devices.
  • Switches controlling pool or spa lights or pumps must be located at least 5 feet from the outside walls of the pool or spa unless they are separated from the pool or spa by a wall.
  • Low-voltage light fixtures (aka: luminaires) must be no closer than 5 feet from the outside walls of pools, spas, or hot tubs.
  • Electrical service wires overhanging a pool, spa, or hot tub must be at least 22 1/2 feet above the surface of the water or surface of the diving platform.
  • Data transmission wires (telephone, internet, etc.) must be at least 10 feet above the surface of the water in pools, spas, and hot tubs.

Call Before You Dig

While not required, you may want to consider calling 811 (the national “Call Before You Dig” hotline) at least three days before you plan to dig anywhere on your property. The hotline personnel will notify all utility providers in your area. Those with lines running through your property will send out a representative to mark their line/s on the ground. You can use power equipment to dig no closer than 24 inches to marked lines, but you must use a hand shovel when digging within 24 inches of either side of a marked line.