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September 1, 2003

Understanding Electical Wiring of 1928

Over the Labor day weekend we did a complete overhaul of our bathroom. For the most part it was just a lot of labor, but there was one piece I actually found quite challenging/rewarding—rewiring for a new vanity light.

Our house was built in 1928, so in tackling any remodel project we're never quite sure what will come up that will lead to hours of research online and several trips to Home Depot to rig up the new to work with the old.

Monday morning I was faced with putting on a new vanity light. I put in the box and pulled the wire through the wall, but when it came time to hook up the electricity I got stumped. In the 4 existing boxes (ceiling light, two vanity lights, switch box) there was a slew of wires coming and going to places. I did what seemed right theoretically, but ended up with lights that couldn't be turned off.

I called dad, who's an expert at wiring (built a museum about it at theschool where he teaches), and over the phone we used my multimeter to determine where the power was entering the bathroom and which wires were travelling from box to box. In the end we discovered that the wiring was running exactly opposite of intuition. We assumed the power went through the switch and then up through each of the light boxes. However, our tests indicated the power was coming into the ceiling light and then down through the vanity lights to the switch, exactly opposite of intuition.

In the end it was a rewarding experience in mapping flow of electricity. Once we figured out how the wires were set up I ended up solving the new-light problem in a way cleaner than my first approach.

Posted by mike at September 1, 2003 10:59 PM