Analog Angle Article

3 wires, 5 mistakes: What’s wrong with this picture?

Many years ago, from what I have read, there was a very popular feature in newspapers (what were those, anyway?) and magazines entitled “what's wrong with this picture?”. In this feature, the reader would be told how many things were wrong, and be challenged to try and find them all.

I had a similar experience the other day, when we had a new dishwasher installed (my previous take on looking for a new unit is here). The new unit “died” the second time we used it. I was torn between contacting the unit's manufacturer (“your new product is a lemon”) or the plumbers who installed it (“hey, it wasn't us, it was working fine when we left”). I decided to do neither, and do a little basic troubleshooting instead.

Since the unit was dead, with no panel lights at all, I checked the obvious first, and found the AC line leading to the unit was fine. So the problem, whatever it was, was within the dishwasher, and not a bad AC feed. I took off the dishwasher's kick panel to check the primary wiring, which consists of just three wires–hot, neutral, and ground –which “simply” need to be connected to their corresponding wires on the AC supply line, via wire nuts for hot and neutral.

What I saw both stunned and shocked me (only figuratively for now, but perhaps literally later on). Here's what I found when I opened the dishwasher panel:

  1. The two wires for each of the AC connections (the black pair, the white pair) were not inserted INTO their wire nuts. Instead, only one wire of each pair was actually in its nut, the other wire was wrapped around some bare copper outside the nut. What happened then was that one of the “wraparound” wires loosened, and that's why the dishwasher died second time we used it. [Whether you put the wires in the nut straight or twisted (and both ways are OK by the code), the two wires do have to go into the nuts to stay connected. Also, any exposed copper outside the nut is dangerous, it is a safety hazard and can short to the dishwasher.]
  2. The safety ground wire was not under the screw, it was dangling in the general “area” of the ground screw, but the screw was loose, had not been tightened at all! This is very bad—that ground wire is there for a good reason.
  3. The same not-attached ground wire was looped counterclockwise, for when it might be connected. Basic, fundamental rule is that a wire goes clockwise under a screw, not counterclockwise.
  4. The protective safety cover over the AC connections was not installed, it was on the floor under the middle of the dishwasher. It takes less than a minute to clip it on and screw it down.
  5. The large nut around the power-wiring conduit entry was not tightened at all, it was loose. (This was the least of the five problems.)

So we have five mistakes with a three-wire connection, which is truly an amazing accomplishment and ratio (1.7 errors/wire). I'll always keep in mind that you should never assume that because something is simple, there aren't a lot of ways to screw it up though sloppiness and negligence.♦