So part of my job is ordering items that the different departments need. Our electrican needed me to order a power adapter with some specific specs, one of which being an output of 5A. I found one on Amazon and sent him a link to verify it matched what he wanted and got the ok to order it. So I went ahead and did my thing, got them ordered and waited. Cut to about a week later, he’s coming to me with the adapters he’d just gotten. Telling me they were the wrong amperage. Well, my first thought was Amazon had made a mistake cause I’d triple checked everything before ordering, so I ask to see the adapter. The following conversation occurred.
Me: Oh it’s ok. It just says 5000mA. That’s 5A.
Him: No…it’s not. I need 5A.
Me:… Uhh… milli means 1000…so there’s 1000 milliamps in 1 amp.
Him: No, a thousand is K.
Me: Err not in metric…here…I’ve got a website here where I can put in mA and it’ll convert it to amps.
Him: watches me do the quick convert that clearly says 5A I still don’t think it’s right…
In the end he begrudgingly dropped it after I told him I was 100% positive that was a 5A adapter. But I could tell he didn’t believe it. I just asked him to let me know if it didn’t work so I could order something different. He hasn’t brought it back lol. In his defense, he was very polite about the whole thing and not getting angry or condescending. But honestly, I’m shocked. Isn’t that something an electrician should know? He’s in his late 50s so maybe that has something to do with it?
I think the issue is that he’s an electrician, not an electrical engineer. He’s working above, what, 10 amps or so where an EE is regularly working with milliamps.
But there are some goofy things in electrical engineering:
When analyzing a DC electrical circuit, we place an arrow next to the wire to signify the direction of current. But the electrons in the wire move in the opposite direction.
The symbol for a physical quantity, and the symbol for its unit, are usually different. An example for mass is m = 40 kg (m and kg are different). An example for time is t = 20 s (t and s are different). And example for current is I = 45 A (I and A are different). But the symbol for voltage, and the symbol for its unit, are the same. An example is V = 30 V.
Hard to believe an electrician never encounters anything rated in mA. On rereading the OP I have no idea what he was thinking anyway. He does think kA means one thousand amps I guess, what does he think mA means? And shouldn’t looking at the device make it obvious that it it’s not rated for 5kA?
Australia is a metric country. Our whole manufacturing industry, and our construction industry, operate with mm. Not meter, cm, dm or anything else. Because workers don’t understand decimals. I just came home with a 2400 x 600 hardi-flex external-eave panel.
This is not new. Non-academic students didn’t understand decimals even when I was a student. There wasn’t any question about it when we converted: The manufacturing and construction industries knew that the workers couldn’t do decimal conversions.
It bewilders me when people suggest that an advantage of metrication is the ease of conversion from 2400 mm to 2.4m.
It’s even more straightforward than that. I’ve run into people who were convinced that milli was short for million. So, even if you can do the math, 5000 mA = .005 A.
“The same?” I’m used to using E for voltage (i.e., E=I*R). As I tell my students, it’s comparable to the way we measure speed…we can use MPH or KPH as the units, but we’re still measuring the same thing.
When I started out in college learning the real dc basics, we used “emf” (electro-motive force) for a few months before they told us that everyone used Voltage for that, but not to lose track of the fact that emf is what voltage is.
Nobody measures power in kWH, as that’s a unit of energy (kilowatt * hour), same as horsepower-hour. Perhaps you’re thinking of kW (kilowatt).
The ampere is a measure of electrical charge moving past the measuring point per unit time. The basic unit of electrical charge is the coulomb, and corresponds to the amount of charge carried by 6.242x10[sup]18[/sup] electrons. 1 A is equal to 1 coulomb of charge flowing past in one second of time.
The coulomb is an SI unit, the SI system being the modern descendant of the metric system. To my knowledge, there is no equivalent unit for electrical current or electrical charge in the imperial/US customary system.
If you want to see an astonishing example of this, check out the Verizon dollars and cents fiasco. Short version: a cell phone customer received a verbal quote of “0.002 cents per kilobyte” for cellular data service, and was subsequently billed for $0.002 per kilobyte. He struggled to find a Verizon employee who could understand the difference.
Often in convenience stores you’ll see items on the counter with a sign that says “0.05 cents each” or some such thing, and as soon as you try to buy one they’ll jack up the price a hundredfold.
There are people who abbreviate nanometer as “nm”. And there are people who abbreviate nautical mile as “nm”. Both are units of length, so superficially similar. Rarely do they intersect, and those of us who are familiar with both know by context which is which. But much hilarity ensues when someone who only knows one abbreviation comes across the other.
Honest question - Why would the manufacturer label the unit as “5000 mA” instead of “5 A”? That’s like a store pricing an item at “500,000 cents” instead of $5,000" - I mean, they mean the same, but…
An example is V = 30 V.