AC or A/C?

Here's a cool question for this time of year that addresses a spelling that many people rarely think about. See if you know. 🤔

What is the correct way to abbreviate "air-conditioner" or "air-conditioning"?

1. AC

2. A/C

3. Both are correct

And the correct answer is the third option. Both “AC” and “A/C” are correct. But why the slash in one form? The reason is that “AC” has a history going back to the early 1800s of being used in building and engineering for "alternating current.” A need to abbreviate “air-conditioner” or “air-conditioning” came about many decades later, and the “A/C” form was adopted to serve the purpose of making “AC” and “A/C” distinct in contexts like building wiring, where the two abbreviations might appear close together. But either form is now correct; “AC” is not exclusively used for “alternating current.” On whether to hyphenate or not hyphenate “air-conditioner” and “air-conditioning,” however, the guidelines aren’t as clear-cut. Although the dictionary currently used by the Associated Press Stylebook, Webster’s New World College Dictionary, does not use a hyphen in “air conditioner” and “air conditioning,” most other major U.S. dictionaries do, including Merriam-Webster's Collegiate Dictionary and the American Heritage Dictionary. Now you know. Be sure to stay cool the rest of this summer with your own AC, or A/C..