Measuring Amperage for Dummies

Suppose you wanted to make money by answering questions on the internet. Of course, you could always just put up a page with a blank that says, "Ask Question Here"; pretty much the Google model, in truth. Since that idea was already taken, the people at Demand Media (now known as Leaf Group) created eHow.com, which hired random people to answer questions that had already been asked. Unfortunately, that meant that sometimes people who knew nothing would still try to answer questions that made no sense. After all, saying "You can't do that!" wouldn't make them any money! Instead, you end up with the kind of foolishness exhibited by Bob White (he's a bird!) when he attempted to explain "How to Calculate the Amps of an Outlet Using a Multimeter" at HomeSteady.com. Ouch.

The big problem, of course, is that multimeters don't calculate anything, including amperage: they can, however, measure amperage in a bare circuit or the voltage at an outlet. White actually gets at that problem in his intro:

"You cannot directly measure the amp load of an outlet; that would create a zero-load power source and open the electrical breaker..."

Interestingly enough, White's post is the only internet occurrence of the phrase "zero-load power source"; which we suspect is because there is no such thing. Regardless of his claimed "diploma in home inspection," we think we'd pass on letting this guy inspect any of our houses... So given that you need to actually insert the ammeter (or multimeter set to measure amperage) into a circuit with a load to measure amperage, White more or less copies the instructions given here – with one exception: the wikihow writer says to "Consult a real electrical workbook (not an online source) before attempting this" – Bob omitted this warning, perhaps because a questionable "online source" would probably mean eHow...

Without belaboring the point, White instructs his readers to destroy the power cord of an electrical device by stripping the insulation off the hot wire. Why, if he insisted on a direct measurement, he didn't tell the reader to construct a special mini-extension cord with an open hot wire, we'll never know...

Of course, the OQ probably just wanted to know how to calculate the amperage at a given outlet, which is pretty easy given that every electrical device has its wattage on the name plate. You just total the wattage of all devices plugged into the outlet and divide that number by the line voltage (probably 110). Say, an 1100-watt toaster and an 800-watt coffee pot, for an amperage of 1900/110 = 17.8 amps. But White wasn't going to get paid for that kind of answer, so instead he headed straight for Dumbass of the Day territory. Well done, Bob...

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