Adventures in Not Electrocuting Myself

I’m not sure I have enough interesting pictures to help tell this story as effectively as I’d like, but as it’s indicative of the kind of chicanery I get up to on a reasonably regular basis, I figure I should regale my reading public with the tale anyhow.

The Spiders#

My wonderful and patient wife, Evelyn, like many people, doesn’t like spiders very much. This has been the cause of a certain amount of consternation, particularly since moving to a place (the Pacific Northwest) that is particularly hospitable to arachnids of all varieties. Oh! That reminds me of this super-fun-and-not-in-any-way-concerning picture I took of the bottom of our mailbox this fall:

To whit: I occasionally take it upon myself to spray some pesticides around various corners of our home, to forestall the otherwise-inevitable 8-legged gentrification of our various interior living areas. The general timeline goes like this:

• Ev finds a spider, and does a very good job of not Freaking Out
• Kill it with a wet paper towel, provide its body for visual inspection (we’ve seen enough movies to know the killer isn’t dead unless you find the body)
• Flush the evidence
• Spray the house
• Hopefully several weeks go by
• GOTO “Ev finds a spider”.

As you may imagine, as I’m spending so much time talking about spiders and spraying for (against?) spiders: Ev recently found a spider, and this weekend was thereby ripe for spider-spraying. So, after making Swedish pancakes for breakfast, I started my day of chorin' by “letting” the various crevices of our home “have it” with a quick squirt of deadly (to spiders and other household pests) chemicals. Thence: bunches of yard work. (I’m convinced it will never stop seeming weird as hell to me that I need to do yard and garden maintenance in January and February. My Midwestern Lizard Brain still believes all of nature should be dormant until, like, May).

So it was that, while swapping out a new hedge-trimmer battery to charge, I noticed that the indicator light on the charger wasn’t lit. The reset button the power strip into which it was plugged yielded no positive results, nor was the breaker for the circuit tripped. Investigating farther afield (although it was, in fact, directly underneath the breaker box), I realized that the lone GFCI outlet that shares a circuit with the rest of the 120v outlets on the East wall of my garage was tripped. I dutifully reset the outlet, and happily noticed all the correct lights come on from the various devices plugged into outlets on the shared circuit, but was very quickly robbed of my good mood by hearing the GFCI device pop only about 30 seconds later. At this, my reaction was a sinking feeling, followed by a string of cursing, as the only device plugged into that outlet is my beer fridge.

The Beer Fridge#

As any responsibly over-the-top homebrewer does, I have a chest freezer I use to store kegs of my beer (sometimes referred to as a “keezer” or “kegerator”, but we usually just call it the “beer fridge”). In order to make sure the interior stays at proper beer storage/serving temperatures, and not — you know — freezing, I make use of an “external override thermostat”. It’s a unit that plugs into the wall outlet, and into which you plug the thing upon which you’d like to override the thermostat. There’s also a temperature probe (since it is a thermostat itself, it needs to know the temperature of the thing it’s controlling), which in this case sits at the bottom of the beer fridge.

I’ve been using this unit for nearly 8 years now, and it’s proven incredibly useful, and generally worry-free throughout its lifetime. It does — as they say — what it says on the tin. You set the temperature you’d like it to keep, along with an acceptable margin of error, and it uses what I like to call “fancy math” (a Proportional-Integral-Derivative control loop) to kick the compressor on and off just the right amount to keep the temperature at the right spot. This is the same fancy math with which I control the temperatures during my brewing process, and by which your car knows how to give just enough gas to keep you moving at 70MPH despite the fact that you just hit a big hill while on cruise control.

So, fighting off a sinking feeling that all my beer was about to become very garage-temperature, I started unplugging things. I was quickly able to confirm that the compressor itself wasn’t bad (thank goodness), since when I plugged it directly into the outlet, it would happily run without tripping the outlet or the breaker. Only when I plugged the fridge into the PID thermostat, then plugged the thermostat into th wall would it trip the GFCI device. Apparently, this morning my PID thermostat had decided to stop working. Joy.

Debugging#

Well, nothing to be done but start tearing things apart, and hope maybe:

• I can find out what’s wrong
• I can put Humpty Dumpty back together again if/when I do

Thankfully, in a scenario that’s entirely too rare in my day job (software), I was greeted with an immediately obvious potential proximate cause: The plug was jacked up.

Okay, no biggie. During the process of building my electric brewery equipment, I got pretty familiar with swapping various kinds of plugs (not to mention growing up watching — and sometimes helping — my dad wire new circuits into our various houses with in-hindsight-kind-of-concerning frequency), so I busted out my wire cutters and strippers¹ and took a look at what was inside the power cord. What I found was, again, immediately visually obviously not normal.

Apparently something had taken all the previously nice, shiny copper strands making up my ground and “hot” wires in my plug and coated them with some kind of black substance. Carbon? Sharpie? Hexxus?

Whatever it was, I figured it probably didn’t conduct electricity quite as well as normal, clean, copper wire. So, like an enthusiastic new surgeon during the Napoleonic wars, I started amputating. After about the fourth inch of dissected cord, I started thinking maybe the entire thing was jacked up, but the black wire was showing signs of life, so I kept digging. Eventually, after about two solid feet of cord, I finally got to a spot where all three wires looked like normal copper.

After deciding the weird blackness was probably a problem, and ensuring I’ll find tiny bits of wire insulation every time I sweep up my garage for the next decade, I was finally ready to swap a new plug onto this much more … succinct cord. Thankfully, that’s about $7 at Lowe’s, and not the $100 or so a new unit would’ve cost me².

At this point, I plugged it back in, and prayed the silent prayer of every person who’s just done electrical work that they barely understand. Thankfully, in this particular case, my meager skills and experience paid off with a newly-functioning PID controller, and thereby a fridge full of beer no longer in danger of becoming warm. And there was much rejoicing.

So Why Did This Post Start With Spiders?#

Ah yes. I almost forgot. Now that my fridge was working again, and all my beer was safely returned to the loving embrace of sciencely-directed cold storage, I started to wonder exactly how the plug had managed to fry itself so thoroughly and — seemingly — at random.

What had made my electrical device, nestled neatly behind my beer fridge, short out this morning of all times? What was I doing this morning, again?

Ah. Right.

Apparently electrical devices dislike being soaked in household pesticides. I had somehow managed — in my blind “yeah, that should do it” aiming at the corners of the garage — to direct the stream of spider-killer directly onto the plug leading into my temperature controller. If I had tried to do that, it would’ve taken me 100 tries. But you know what they say: sometimes it’s better to be lucky than good.

Thank goodness I’ve still got all this cold beer.

—Greg

Footnotes#