Association of Home Appliance Manufacturers
How to Install Surface Wiring
In surface-wiring systems standard 120-volt wires are installed in metal or plastic channels (raceways) wthat are fastened to interior surfaces -- at baseboards, under wall cabinets or across finished walls, floors or ceilings. (Coaxial cable, communications, audio system, and other low-voltage wiring may also be installed, but wire must never be in the same channel or terminate in a wiring box with 120-volt wires). An add-on installation usually taps into an existing outlet (receptacle or light) and extends power to a variety of surface-mounted devices (switches or receptacles) or outlet boxes.

Typical applications include: temporary wiring (lowering a light switch for young children or adapting a space for a home office); wiring for concrete or cement block-walled basements, garages or shops (dry locations only); multiple receptacles for kitchen counters; or convenience receptacles or outlets for lights, a ceiling fan or other electrical fixture anywhere in the home. Metal systems are functional, impact resistant, and a good choice for workshops and the like. Decorative plastic systems are, by design, usually better looking and easier to install and rewire if changes are required in the future.

Skills involved are minimal, but do assume a basic understanding of how your electrical system works, basic wiring skills, and how to wire switches, receptacles, and lights.

Preparation

To begin, draw a simple plan that uses material efficiently and/or is least noticeable, depending on the location. At the service panel, identify the capacity of the existing circuit (usually 15 or 20 amps). Then verify that it can handle additional outlets: shut off power to the circuit by tripping the breaker or pulling the fuse then use a test lamp to identify all outlets (receptacles and lights) that are on the circuit. Allowing 1.5 amps for each outlet, a 15-amp circuit (as determined by the fuse/breaker capacity and minimum No.14 awg wire size) will handle 10 outlets, and a 20-amp circuit will accept 13 outlets.

The plan should also list the number and type of outlets (receptacles, lights), both existing and proposed, and the location (kitchen, basement, etc.) involved. Review those plans with a licensed electrician and/or an electrical inspector for your locality. Discuss local electrical codes that govern what must be done, who can do the work, and if inspections are required or advised.

Next, obtain a catalog from a wiring system manufacturer or work with a local dealer to prepare a list of materials, including raceways, connecting fittings; and wiring boxes; also gather equal lengths of black, white, and green Nos.12 or 14 wire and any needed devices. To fasten raceways you'll need appropriate fasteners: For wood (or drywall at wood stud locations), use flat-head wood screws; for drywall, use plastic shields with flat-head wood screws; for plaster, brick, concrete or masonry, use plastic shields and flat-head sheet metal screws; and for tile, use toggle bolts or plastic shields with flat-head wood screws. Finally, collect the required tools: standard and long nose pliers, slotted and Phillips head screwdrivers, wire snips, utility knife, fine-tooth hacksaw, and fine tooth file. An electric drill/driver may also be required.

Installation

Transfer your plan to the wall using a level and pencil to mark raceway, fitting, and wiring box locations. Shut off the power to the circuit at the service panel and verify there is no power at the existing outlet (use a voltage tester or plug in an electric tool/lamp that you know is in working order). Remove the outlet cover plate and attach an extension plate with screws provided. Then, loosely install all other mounting plates, using the appropriate fasteners. Measure and cut raceway with a fine-tooth hacksaw. Connect the raceway to mounting plates and the surface, attaching fittings, such as elbows and T's, where required. (Depending on the system, the raceway may fasten directly to the wall or to preinstalled clips.) Then finish securing mounting plates and install wiring boxes (extension frames) to the mounting plates. Follow manufacturer's instructions regarding notching the boxes to accept the raceway. With metal systems, make sure you file any sharp edges after cutting and use bushings as recommended.

Wiring

Finally, begin wiring. Fish three lengths of wire between each box location, allowing a minimum of 8 inches extra at each end for splices. Rewire the existing source outlet creating a pigtail connection for hot, neutral, and ground wires; connect the corresponding wires in the new surface system and wire all new devices and fixtures. Perform the continuity tests to confirm proper grounding and polarity within the new system before restoring power.

Written by Roy Barnhart
Copyright HouseNet, Inc.

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