There are different rules and guidelines that we have to adhere to when we are using indoor vs outdoor wiring. For example for safety precautions we have to more conscious to use PVC pipe when running dedicated circuits for outside wiring whether it be for outside security lights or hot tube or pool wiring. We can also run UF cable which stands for “underground feeder”. This is also an acceptable method to be using. This is a great article on Outdoor wiring and lighting to make sure that either you as an electrician or if your a homeowner, your technician is installing your wiring properly.
Rules for Installing Outdoor Wiring and Lighting
by Allen B. Ury
Electrical power isn’t just used indoors. Electricity is used extensively outside, too. Municipalities use electricity to power things like street lamps and traffic lights. Businesses use outdoor power to illuminate store signs, billboards and parking lots. And, of course, individual home owners use electricity to provide outdoor mood and security lighting, as well to provide “juice” to electrical-powered garden tools, barbeques, swimming pool filtering systems, water heaters and hot tubs.
For obvious reasons, outdoor power systems are built to even higher standards than indoor ones. They have to withstand extreme heat, cold, rain and even floods.
Back in 1897, the National Fire Protection Association (NFPA) developed the National Electrical Code (NEC) to establish rules for the installation of indoor and outdoor wiring. Updated every three years, the NEC has been approved as the nationwide standard by the American National Standards Institute (ANSI). Although the NEC has no enforcement power behind it, many cities, towns and other municipal jurisdictions use the NEC as the basis for its own local electrical codes.
Here are some of the rules the current NEC has established for installing outdoor residential electrical systems:
1 Before digging to install outdoor cables, call your local utility company. A representative will come to your site to identify any obstructions you may encounter.
2. If you’re burying your outdoor wiring inside a protective tube, use schedule 80 PVC (identified by its grey color). Schedule 80 PVC is more durable than the white PVC used for plumbing. Wirings inside schedule 80 PVC should be buried a minimum of 18 inches below the surface.
3. You can avoid using PVC entirely if you use UF cable, which has its own heavy-duty insulation. The trade-off is that you have to bury the cable deeper; 24 inches below the surface, to be exact.
4. Protect outdoor receptacles (sockets) with either ground fault circuit interrupters (GFCIs) or GFCI Breakers.
5. Mount outdoor receptacles and switches inside weatherproof electrical boxes.
6. If you have more than four receptacles on a single circuit, or if you have an outdoor lighting system with even one lamp that exceeds 300 watts, you need a dedicated 20-amp circuit to carry the load.
7. If you’re positioning a receptacle in the middle of a yard, you need to install it inside a box that’s attached to a 12-inch-high post or driven into the ground.
These are just some of the rules governing outdoor electrical lighting systems. They’re part of the basic education you’ll receive as part of the Electrician career training program at WyoTech.