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How do you change a four prong appliance to work on a 3 prong outlet?

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Wiki User
2015-07-15 18:28:50
2015-07-15 18:28:50
for USA, Canada and countries running a 60 Hz supply service.The 4 wire plug has a ground connection and the 3 does not.

3 wire plugs are old and outdated. Way back in the old days they didn't ground equipment so plugs didn't have a ground. (Remember the old 2 wire 110V outlets on houses built before the 50s?) A few people got killed so they decided to add a safety wire. It took them longer to catch on with heavy appliances, but eventually they did. That is what the fourth pin is for. Since many homes still have the 3 wire plug it is allowed in older homes. New homes must use the new 4 wire plug.

Changing your 4 wire cord to a 3 wire cord is the same as plugging a 3 wire 120V appliance into one of those 3 prong to two prong adapters they sell. Your appliance works now, but is ungrounded.

Don't listen to anyone who says to replace the new up-to-code plug with an older plug. That is the same as replacing your 3 prong 120V outlets with old two prong outlets! Ignore anyone who tells you to do so, they think they know a lot more than they actually do. Buy a new cord. It is cheap and safer.


Although configuration of the plugs are not universal, NEMA has a huge listing of plugs and receptacles. Once you know which one you need, all you have to do is rewire it. Your old range didn't have have ground (bare or green wire, which only carries current in a fault situation). The new one you have purchased does. Although you do not have to hook this wire up for the range to operate, there is a severe risk of electrical hazard. The best advice anyone can give you is that you must run a new power cable to the range's location, one that includes a ground wire. This is a lot of work, but it has to be done for the installation to be safe.


[Note: don't do this! See the first answer to this question!]

This may or may not be allowed by the electric wiring code operating in your town or location - it is best to check with the appropriate electrical safety officer in your locality before you do any of this: Change the cord on the new range to a three wire cord. Buy a new three wire cord for the receptacle configuration that you have. Remove the four wire cord from rhe range, taking note where and how the wires are attached, especially the white wire and the bare or green wire. Attach the red and black hot wires to their respective terminals. Attach the white neutral wire to its terminal and use a ground jumper (bare copper wire #10 gauge) to attach the frame of the range back to where the white wire is attached.


As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.




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US NEC: You don't. If the stove has a four prong outlet, it is probably used in a mobile home application. Per the NEC, in a mobile home configuration for a stove you must maintain the ground separately all the way back to the distribution panel.

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