| Wiring a Circuit |
| Student Jerry Harper takes his first lesson in wiring a circuit panel. |
From "Trade School"
episode DTRS-205 |
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In this episode of Trade School, Jerry puts his understanding of basic electrical theory to the test by wiring-up a mock bathroom at his school lab.
Basic Tools:tape measure
hammer
gang boxes
NM 14-gauge wire
linesman pliers
wire cutters
cable strippers
cable staples
wire strippers
two-screw cable connectors
copper crimp sleeves
side cutter
wire nuts
screwdriver
volt-ohm meter This simulated residential project includes a three-way switch for the light fixture. Typically used for hallways and staircases, three way switches are used in instances where two separate switches control one. Note: For instructional purposes, the main circuit panel is located within this mock bathroom. In a typical residence, the circuit panel would most likely be located in another area. Safety Note: - Unless absolutely qualified for system installation, it's recommended that you leave the installation of your home's electrical system to a licensed electrician.
- Always turn off the power to the circuit before beginning any electrical work.
- Use a tester to verify the power is disconnected.
Armed with a wiring diagram and the necessary tools, Jerry begins by installing the boxes that house the switches. According to job specifications, the boxes are hung at 48 inches from the ground. The boxes come with their own attachment nails, so he simply hammers the boxes into the first available stud from the doorframe (figure A). Note: The metal boxes that house the overhead light and fan have been permanently installed for instructional purposes.Jerry now snakes 14-gauge non-metallic (NM) sheathed cables from the main panel, through pre-drilled holes in the studs and up to the boxes (figure B). From the boxes, he runs the cable up and along the joists to the ceiling boxes that house the fan and light.
With the cable in place, Jerry fastens it to the framing with brackets called staples, every 4 1/2 foot, at turns and where the cable enters a box (figure C). He cuts the cable to length with linesman pliers, leaving some excess at the boxes for his connections (figure D). In a typical residential situation, this would complete the "rough-in" stage of the job.
Jerry uses a cable stripper to slit the cable's plastic insulation, which he peels open (figure E). This exposes the color-coded hot (black/red), neutral (white/yellow) and ground (green/bare) wires within the cable. He trims the peeled insulation with wire cutters.Before stripping the cables that feed the overhead fixtures, Jerry installs two-screw cable connectors (figure F) into the holes called knockouts, out of the boxes. These connectors serve not only to protect the wire, but also to hold them in place.
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