I know this is a lightning forum but since most people here are good with electrical stuff in general I thought I’d ask.

I’m planning to get a gas generator this spring for unrelated reasons and figured i could also use it to finally fire up some of my 240v lamps. I notice most generators have a outlet marked 120/240v but no visible way to change the voltage. How exactly would you get the full 240 from the thing rather than standard 120?

The 120/240v outlet on a generator is wired similarly to dryer or range 4 prong outlets except in a twist lock format. On those outlets you have Line 1, Line 2, Neutral, and Ground. The voltage between L1 and L2 is 240v. L1 or L2 and Neutral is 120v.

Might have to double check but it looks like a NEMA L14-30R outlet so there should be a piniut chart online or even marked on the outlet itself.

Note the standard NEMA 5-15 outlets on the right only provide 120v.

So all I’d need is that 4 prong plug wired to a mogul socket cord to get the full 240 volt?

Yeah pretty much. Home Depot should have the plugs for these. The inside of the plug should have a pinout for each prong. The twistlock plugs are kinda expensive though.

Since I'm assuming you don't need 120v, you can use a 3 wire cord and leave the neutral inside the plug not connected. That'll get you 240v with ground.