How to Add a Junction Box & Electrical Code
The National Electrical Code (NEC) requires all junction boxes to be securely attached, with a cover and full accessibility. The number of conductors in an electrical box cannot exceed a specific amount, determined by the volume of the box and the type of wire used. All splices, switches, receptacles, junction points and pull points have a electrical box. A non-metallic rectangular box (2 and 1/2 inches by 4 inches) can be used for receptacles, switches, junctions or light fixture installations on walls and ceilings. Clamps are not necessary if the wire is stapled within 8 inches of the box. The measurement of conductors in a box is measured in cubic inches (CI). The wire, clamps and electrical device, such as a switch or receptacle, are included in the calculation. Does this Spark an idea?
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Things You'll Need
- Electrical box
- Connectors
- Screws or nails
- Drill or hammer
- Wire nuts
- Electrical box cover plate
Instructions
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1
Secure the box to a wall stud, rafter or joist. Use screws or nails. If using a metal box, install a connector for each of the wires or conduit runs.
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2
Push wires through the connector into the electrical box. Leave at least 6 inches of wire in the box for a splice, or push the conduit runs into the connectors. Secure the wires or conduit in the connector with the screws on the connector.
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3
Cut the plastic coating off the wire with a utility knife and strip 1/2 inch of the insulation off the end of the black and white wires. If using wire, such as 12/3 with ground, there will be red, black, white and uninsulated copper wires. The space allotted for 14 gauge wire is 2 CI, 12 gauge and 10 gauge is 2.25 CI, 8 gauge is 3 CI and 6 gauge wires is 5 CI.
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4
Connect splices together with wire nuts. Connect the same color wires together. Push the wires inside the box and install the box cover plate. Do not bury the electrical box in the wall or ceiling. If in an attic, do not cover the box with insulation. An access panel will need to be installed if the area is to be finished with wall covering.
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Tips & Warnings
The holes in the wall studs and joists that you run the wire through have to be 1 and 1/2 inches into the wood or covered with metal plates, so the nails or screws will not puncture the wires when the wall is being finished. If the wire is run in an attic, the wire can run over the joist, but not within 6 feet of the access and the wires need to be stapled every four feet.
To prevent electric shock injuries and electrical fires, always make sure the wire nuts are tight and no uninsulated copper is exposed, except for the ground wire. Check local codes before starting your project, "National Electrical Code (NEC)"codes may vary from local codes. Use rubber insulated gloves when working with electricity. Never work in the panel box when it is "Live".
References
Resources
- Photo Credit electrical box image by jimcox40 from Fotolia.com
