Thoughts on what these old 6-20R outlets were actually intended for?

I've run into those 6-20Rs alot in older light-industrial spaces. ussually, they were installed specifically for a dedicated piece of equipment that pulls 240 volts. In the shops I've worked in, that single round face was almost always for a mid-sized air compressor or a heavy-duty table saw like an old Delta Unisaw. The reason it's a single outlet instead of a duplex is often becasue the electrical code or the specific equipment manual required a dedicated circuit to prevent people from plugging in multiple high-draw tools at once. If you're thinking about swapping it out, definately check your breaker panel first. You’ll likely find a double-pole 20-amp breaker feeding that spot. If you swap it to a standard 120V duplex, you're going to have to reconfigure the wiring at the panel and potentially the neutral situation, depending on how they pulled the wire. I’d keep it if you ever plan on running a small welder or a 2HP motor. Those single-face outlets are built like tanks compared to the cheap residential stuff we see now.

acutally, I tend to see those 6-20Rs in the corridors of older hospitals and large office complexes more than in woodshops. In my experiance, they were almost always installed specifically for high-pressure steam cleaners or those massive Tennant floor scrubbers that need the extra kick. The single face isn't just a relic; it is a very intentional safety design. If you swap that out for a standard duplex, you are just asking for a headache. Someone will inevitably try to run two high-draw pieces of equipment off that 20-amp leg at the same time, and you will be resetting breakers every morning. Those single-face outlets are a clear signal to the cleaning crew that this is a dedicated circuit. I have seen people try to use sketchy adapters to run 120V gear off these 250V lines, wich usally ends in smoke. I whould leave it exactly where it is. It serves as a visual boundary that prevents the circuit from being overloaded by mistake.

Have you ruled out that it was just for a specific high-capacity photocopier? In some of those older commercial layouts, they’d drop a single 6-20R specifically becasue the lease agreement for the office equipment required a dedicated 240V line to avoid tripping the circuit during a big print job. I'm a bit skeptical about the 'industrial' angle if the wiring doesn't look heavy-duty. Before you tear it out, have you checked the conduit? If it’s just a single run of 12 AWG, it might have been for a very specific, low-duty cycle machine rather than a shop tool.

Don't forget about those beastly old window units. I've seen 'em in plenty of shops where they didn't have central air, and a 6-20R was the only way to get a 15,000+ BTU monster running without melting a standard outlet. Honestly, if it's still got juice, I'd leave it. You'll kick yourself later when you buy a small stick welder or a big compressor and realize you gotta hire a sparky to run a new 240 line becasue you swapped that one for a 120V duplex you don't even need.