3 prong plug, can I use in 2 outlet?

No . .. a 3-prong plug will not insert into a 2-prong receptacle. ... always glad to help.

ps: if your 1965 house has 2-prong receptacles and a 15 amp service - it's not a house. John T.

A 3-prong grounded GFCI outlet would be my requirement.

Thanks Wes. So no is the answer.

That's what they make adapters for, or dikes if you're really crude. 15 amp service sounds more like 1915 or so.

I was thinking this myself. I use those adapters all the time, just to plug into extension cords (since I have 3-prong receptacles) but this, it turns out, is an immersion cooker. (I didnt' know such things existed, except to make a cup of hot water.) Maybe the only appliance I think really needs a ground, since it's sitting in water or similar. And likely, as in the illustration, in a metal pot, with metal handles!!

So I guess if the center screw on the receptacle is grounded and the OP actually connects the ground lug or wire to the center screw, that would be enough. OP, do you know how to tell if the center screw is grounded, and how to connect the ground lug of the adapter to it?

NEC. GFCI on two wire circuit, yes. It's legal. There are explanations available telling how gfci works if anyone is curious.

A GFCI is required within 6 feet of a water/moisture source, Technically, a single GFCI can be used with other non-GFCI receptacles piggy backing from the GFCI on that circuit, One of those receptacles can be a 2 prong and the worse case is the GFCI will trip.

With an adapter, you can.

Built in 65, it should have 3 prong receptacles since code required them in new homes starting in 62.

You can use it without a ground IF you use a GFCI - it is an imersion heater so it is foolish to use without a ground or gfci or both. Will it WORK with an adapter? Sure - but it would work with a set of aligator clips fastened to the plug too - - - -

ONLY if you can ground the adapter !!!!!!

Sure, it would work physically. But it isn't grounded. The most important thing safety wise is grounding. A legal alternative is using a gfci outlet either in that one box or upstream. Is there any chance a modern gfci breaker would fit in the breaker box? A gfci outlet should fit in that particular box.

Yes, the kind we used to call a 'pigtail' which has a short wire and connector to fit under the grounded faceplate center screw. I have seen some with a 'tab' instead of a wire which functions the same *and* makes sure the polarity is not reversed. Usually, the prongs are different sizes to avoid this polarity problem.

It won't work safely with the typical 3 prong to 2 adapter if there is no ground. The suggestion to put in a GFCI receptacle is the best fix. It can be placed in the most upstream location possible, thereby protecting that receptacle and everything downstream.

Not with a 3 prong to 2 prong adapter if there is no ground at the receptacle cover screw. Even then it's iffy. Put in a GFCI receptacle in the most upstream location possible.

The mechanism for shock would have to be an internal short that makes the case hot, right? The case is in a water bath that you don't touch because it's hot - 150 F or so. You fish out your cooking bags with tongs. So the path is from an internal hot wire, through the water, through tongs with rubber handles, through the human body, through the shoes and out the feet into a floor at ground potential. It's certainly theoretically dangerous but maybe not highly probable to cause harm.

You are making an assumption. It is rated at 800 watts so do the math. Once it reaches temperature does it go to a lesser draw or does it cycle the 800 watt heater off and on?

I doubt it's continous, far more likely it's full on/off. 7 amps would be a750Watt heater, which is reasonable. It's just going to be on for short periods compared to the off.

I saw a show last night showing the kitchen at the Venetian Hotel in Las Vegas. The do servings for groups as large as 4 thousand. They were Sous Viding short ribs, two tons at one time.

I would want it on a GFCI or grounded if I was using it in my kitchen. The path is from any internal short to the metal case. I'm sure there are plenty of failure possibilities that don't need to go through the water.