Take some time to read the following tips and instructions on how to install outdoor wiring from Ace Hardware. These instructions can help you save time and effort, while ensuring a safe and satisfying installation. In this document you will find information about:


  • Your first step should be to check local codes regarding outdoor lighting. Be sure to follow these code requirements carefully.
  • Always use type UF cable for installations requiring underground wiring. The UF implies that there must be a fuse or breaker inside the house at the starting point of the underground wiring installation.
  • For your outdoor lighting project, use only those materials that have an Underwriter’s Laboratory (UL) approval.
  • Cable used for underground installations must contain a grounding conductor. Outdoor fixtures must be grounded for complete safety.
  • Use conduit to protect the cable where it is exposed above ground and where bends are made below ground.
  • Some local codes may require you to cover the entire cable with conduit.
  • Many local codes now require outdoor circuits to be protected with GFIs, Ground Fault Interrupters. There are two basic types of GFIs. One is designed to be installed in a circuit breaker box. The other is designed to fit into outlet boxes. Check your local code.
  • Always bury any underground cable at least 18″ deep, but 24″ is preferable. Cables buried at least 24″ deep are less likely to be bothered by spading forks and other tools commonly used around the yard.
  • For any outside wiring installation, always use weatherproof equipment, such as boxes, receptacles, etc.
  • Remember to shut off the electrical current at the main switch before starting any underground wiring tie-in.


  • Weatherproof switches and outlet boxes are available in both flush-mount or surface-mount styles.
  • The first image below shows a flush-mounted switch and a flush-mounted receptacle. These must always be installed in a weatherproof metal switch or outlet box.
  • The second image below shows a surface-mounted switch and outlet. These are contained in their own weatherproof boxes and can be mounted directly to any flat surface.
  • The third image below shows a weatherproof box. These boxes can be mounted on posts or conduit when you’re installing any switch or receptacle, other than the surface-mounted type.
  • The flush-mounted and surface-mounted switches and receptacles are designed to be completely weather resistant when they are installed correctly.


  • Before you begin, shut off the electrical current at the main switch box.
  • For an underground wiring installation, mount a breaker or a fuse box in a location similar to that illustrated in this image. The breaker box should start the installation no matter what type of cable you are using.
  • Run conduit from the breaker box through the wall to where the weatherproof elbow will be mounted on the outside wall.
  • Continue the conduit down from the weatherproof elbow to where it bends, 18″ to 24″ below ground. Remember, conduit is generally required where the cable bends underground.
  • Your local code may require that the entire underground cable be covered with conduit. The main purpose of the conduit is to protect the cable from spading tools used in the yard.
  • Insert the cable through the weatherproof elbow, and then down through the conduit to the 18″ to 24″ level where it is to be buried. Pull the cable tightly through the weatherproof elbow and reattach the cover.


  • This image illustrates various lighting fixtures and outlet boxes that you can connect to the buried cable at any point. It’s important to plan your yard lighting carefully before starting the job.
  • Plan ahead to determine where to install weatherproof outlet boxes. These outlet boxes are especially handy around patios and recreational areas of your yard. They provide readily accessible receptacles for appliances, record players, radios, Christmas lights, etc.
  • Weatherproof outlet boxes also provide handy outlets for spike lights, electric lawn mowers, electric trimmers, etc.
  • Install protective conduit above ground where any weatherproof outlet box or elbow is installed.


  • Dig a hole about 2′ deep with an ordinary post hole digger or tiling spade. Run cable up through the lamppost, then fill the hole with about 12″ of concrete mix. Insert the lamppost into the concrete mix in an upright, plumb position. Use a long level or plumb bob to make sure the lamp is exactly straight. Remember, you cannot straighten it after the concrete hardens.
  • Use a bent piece of conduit to protect the turn in the cable below the post. This eliminates the danger of trouble at the turn.
  • You may want to use temporary stakes and guy wires to hold the post lantern in an upright position until the concrete dries. Using four guy wires in opposite directions ensures a secure post.
  • After the concrete is completely dry, fill in the hole with dirt and seed around the post for a neat appearance.


  • If the conduit used in underground wiring does not connect to a grounded box, cable with a grounding conductor must be used.
  • Every outdoor lamp part exposed to the touch must also be grounded.
  • Ground all weatherproof outlet boxes to an outdoor grounded box.
  • Ground Fault Interrupters are required in most areas for outdoor circuits. Follow the manufacturer’s instructions for the installation of the type of GFI you decide to use.


  • Many of the newer outdoor lights come equipped with photoelectric eyes or motion sensors, or both. The photoelectric eye turns the light on in the evening and off in the morning. The motion detector turns the light on when it senses motion in the range of the detector. If your light does not have this type of control built in, you may wish to add a timer, photoelectric eye or a motion detector. These devices allow for automatic operation and a greater sense of security.
  • Permanent timer switches are readily available and can be pre-set for any on/off times. Follow the manufacturer’s instructions carefully when installing a permanent timer switch.
  • You may also use portable timer switches with plug-in equipment for outdoor lighting. Use this type of timer switch as you would any other appliance.

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