Be that as it may, Harsch's original post zeroed in on bathroom exhaust fans. We assume that's because it was the only place she found a reference to double switches, probably because she didn't know anything about them. Whatever. Here's what Cecilia had to say about her project:
"To separate the operation of two lights in a room, consider replacing the single switch with a double switch. The double switch lets you operate each light on its own switch, allowing you to turn only the light you need on and leave the other light off. A double switch uses the same space as the original switch. You do not have to cut the drywall to expand the size of the switch box. Wire the double switch using the existing wiring from the single switch."That last sentence is the killer. You see, people who actually know what they're talking about would be aware that it ain't that simple. The position of the existing switch would control the wiring pattern, and only if the switch is between the two lights in the circuit would it be possible to rewire the system without fishing new wire. Harsch never even mentions that little detail! But let's look at what she did say. Of course, she starts out with turning off the breaker. Small props to Cece. And then she starts talking about the wiring...
- "Tie the three white wires together inside the switch box, two white wires connected to the two separate lights and the white wire from the circuit panel." – Sorry, Cecilia, there's a pretty good chance there are only two white wires in there. In fact, there's some chance that there are none²!
- "Connect the three bare copper ground wires together from inside the switch box, the two bare copper wires that lead to the two separate lights and the bare copper wire that leads back to the circuit panel." – You really should ground the switch Cece, either to a metal box or by connecting a pigtail (a word Harsch probably doesn't recognize) to the grounding screw on the switch. Belt and suspenders...
- "Wrap the black wire from the circuit panel around the brass screw on the right side of the double switch." – It would have helped if Harsch had mentioned how to find the hot wire from the panel... but she didn't. And again, that's assuming she found three wires in the box: what if there are only two???
| Harsch apparently picked up her instructions from a printed publication, which (we assume) was accurate for the case in which the two lights have separate supply wires. That's not how electricians work, though: there's a good chance the lights are controlled by a single wire that connects them together. Cecilia didn't mention this. Harsch didn't know about the different possible positions of the switch in the circuit, didn't know the difference between lights connected in parallel vs. series, and never even considered the possibility that the lights might be controlled by a three-way switch. Is it any wonder we thinks she's richly deserving of another Dumbass of the Day award? This makes five... |
¹ The original has been deleted by Leaf Group, but can still be accessed using the Wayback machine at archive.org. Its URL was ehow.com/how_7884742_wire-switch-two-separate-lights.html
² If the old switch is on the end of the circuit, the neutral wire is probably re-coded as hot – look for black tape. In that case, you'd need to fish new wire to the far light: ugh!
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DDIY - WIRING
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