I have a cabin, wired for 220 and even has a sub-breaker near the outlet. There are 3 wires to the connector (two hots and the neutral). The range-top that I want to hook up is a 4-wire model (2 hots, neutral and ground.)
When I put a tester's negative to the neutral, of course either of the hots shows 120v. When I touch the negative to the metal box, the same result with each of the hots (though I can't see any ground wire adapter on that metal box. Touching wallboard with the negative does NOT ground it; when I touch the negative to drywall and the positive to either of the hots, I get nothing.
Questions:
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does this mean that the metal box is itself grounded somewhere/how (so I can just attach the ground wire to it?)
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Is there any cause for concern about wiring these directly, without a plug?
Best Answer
Both of the previous answers are completely accurate. New ranges all come with the new four wire plug, however you can convert to a three wire configuration if your box is grounded (in this case your's is) by connecting the ground lug to the box in the female plug. Although this would not meet current code requirements, it is perfectly safe and this three wire configuration has been used for over 50 years before the new 4 wire config was established. This method is a "common sense fix", but the totally proper way would be to run a new 8/3WG Cu or 6/3WG Alu wire to the panel, assuming a 50 Amp breaker is being used.