This is in the United States. Electrician came out for something else and said these were on their own breaker, probably heaters at one point, still connected and live. I forgot to ask him if we can use these for anything else. The house is pretty old, most outlets are two prong, so if we could convert this to a 3 prong outlet with ground that would be helpful.
This is like an upside down driver connection, but different. I dont know what the format is called.
That is an old 20A 250V outlet. The two slanted terminals are the two 120V legs from your panel giving you 240V. The vertical terminal is your neutral. This is based on it being wired correctly, you'd have to verify that with a volt meter and checking the main panel. There isn't an adapter that would fit into this and give you a grounded outlet. You would be able to disconnect one of the hot legs in the panel and use the other one with the neutral. If there is EMT or other metal conduit, that could be used as your ground when attached to the junction box. You would then attach a ground outlet
That looks like like an old nema 10-20, and probably not allowed any more.
It is probably 240 volts(two hots and neutral or maybe ground).
The circuit itself might be rewired so you can add regular household plugs/outlets, but need to check how it is wired at the panel. Possible you might need to run a new cable from the panel.
Can have a look at this question for more information. Should I bother with this 10-20 plug or replace it?
