🖙No, you shouldn't put a toaster in the dishwasher
Sometimes things stick in my mind, even when I think they've stopped bothering me.
This post by Nicky Case is one such one, my brain rudely deciding to remember it apropos nothing after a long hiatus. Now, I generally like her work—The Parable of the Polygons and We Become What We Behold in particular are great—but this post irked me.
In it, she argues it's actually okay to put a toaster in the dishwasher as long as you dry it out first, and the common sense reaction that this is a bad idea is wrong. Here's her reasoning:
But, if you actually think about the physics step-by-step, an electrical short happens when there's an unintended path for electricity to travel (e.g. through water), which can cause damage. So, if you were to put an unplugged toaster in a dishwasher, then let it dry for several days, there would be no leftover water in it (toasters are designed to avoid trapping moisture), and thus, no risk of an electrical short.
In addition to this theoretical argument, she shared a post where JD Stillwater put their money where their mouth istheir toaster where their dishwasher is, and it worked afterward.
Nicky Case and JD Stillwater are probably right that people overestimate the risk of putting a toaster in a dishwasher. It wouldn't (ahem) shock me if you asked a bunch of people, they would say washing a toaster in the dishwasher basically guarantees you'll ruin it, similar to driving a car into a body of water. And that's probably not correct! I'm sure a lot of the water dries out if you put a toaster in a dishwasher and then let it dry for several days. And there are those experiments—JD Stillwater might be lying or have gotten really lucky but these explanations don't seem that convincing.
Still, this logic has some holes. The thing is, toasters are designed to avoid trapping moisture in a particular set of circumstances. I'm not a physicist, an electrical engineer, or an appliance designer. So perhaps I'm underestimating how much moisture they're designed for and overestimating the chance of shorts from tiny pools of water that failed to evaporate. Still, a dishwasher has way more moisture than anything you're toasting, even considering that modern dishwashers try to conserve and recirculate water, so they use only a few gallons. Also, if you're washing a toaster, you're presumably loading it upside down, where it will stay for a while. That's not a big factor—you're presumably turning it right side up to dry—but it's another departure from the circumstances it's designed for.
Another factor is that recent toasters are more likely to have electronics and those are more sensitive to moisture. I don't think a short in one of those components is as dangerous because of the lower voltage, but it could ruin your toaster1. If you're genuinely invested in doing the experiment and willing to eat the cost of a toaster so you don't care about this risk, fair enough, but it's a pretty sensible justification for people's intuition that this is a bad idea.
Yet another factor that complicates the overall equation and means the experiments may not generalize is that not all water is equally conductive. JD Stillwater knows this because his post has a tangent about running a hair dryer under water and it only shorting out when he added a bunch of salt. The hardness of the water, the detergent, and (because dishwashers recirculate water) the dirt on the toaster itself and other dishes could all affect what's going on. You can partly mitigate this by not putting anything else in the dishwasher and not using detergent, although these precautions were not actually mentioned in the two posts.
(I'd also be remiss to note that while this isn't probably true of the vast majority of toasters, another risk of putting electronic devices in water generally speaking is that, while they may appear to be off, they may contain a battery or capacitor, so they might not actually be powered off.)
Lastly, the most important thing is that, even if people are technically wrong about the magnitude of the risk, they're right about the call safety wise. People can and do die from electrocution from submerged electronics and although electrocution is fortunately pretty rare overall, kitchen appliances are a relatively common cause among the accidents that do occur (e.g., number three in this study. Even if you have some reason to think a risk is overstated, that doesn't mean it's low. And of course, you could be wrong.
Sorry, JD and Nicky, I think common sense wins this one.
People put keyboards in the dishwasher sometimes. If you look at anecdotes, this often works fine, but not always. These might have more electronics (they certainly have more keys than a toaster has buttons), so it's not a perfect comparison. Still, it shows that washing electronic devices in this way is a bit of a gamble even if you set aside the safety risks.↩