Wiring a 240V Appliance: Difference between revisions
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**See Spruce for difference between 3 wire and 4 wire installation [https://www.thespruce.com/installing-a-240-volt-circuit-breaker-1824649#:~:text=In%20a%20pure%20240%2Dvolt,or%20green%20insulated%20grounding%20wire.] | **See Spruce for difference between 3 wire and 4 wire installation [https://www.thespruce.com/installing-a-240-volt-circuit-breaker-1824649#:~:text=In%20a%20pure%20240%2Dvolt,or%20green%20insulated%20grounding%20wire.] | ||
**But - older appliances which were 120/240v, not pure 240 - also had a 3-wire cord, and they combined ground with neutral. But that is no longer allowed as it appears to be less safe - for example if in a non-fault condition, the person has lower resistance than the ground. See [https://www.jadelearning.com/blog/3-wire-cords-on-modern-4-wire-appliances/#:~:text=In%20an%20existing%20installation%20(such,4%2Dwire%20cord%20and%20plug.] | **But - older appliances which were 120/240v, not pure 240 - also had a 3-wire cord, and they combined ground with neutral. But that is no longer allowed as it appears to be less safe - for example if in a non-fault condition, the person has lower resistance than the ground. See [https://www.jadelearning.com/blog/3-wire-cords-on-modern-4-wire-appliances/#:~:text=In%20an%20existing%20installation%20(such,4%2Dwire%20cord%20and%20plug.] | ||
*If you only have a 2 conductor + bare ground, mark the bare ground as a neutral and run it to | *If you only have a 2 conductor + bare ground, mark the bare ground as a neutral and run it to the neutral of the subpanel if you want 240V/120V. It is not clear whether codes allow this. [https://forums.mikeholt.com/threads/3-wire-stove-grounding.2556425/] | ||
*Does a 3-wire 240v circuit have a grounded neutral, or a ground that is neutralized? | *Does a 3-wire 240v circuit have a grounded neutral, or a ground that is neutralized? | ||
*'''Thus: is it safe to say that any 3-wire appliance is pure 240V no 120V? | *'''Thus: is it safe to say that any 3-wire appliance is pure 240V no 120V? | ||
Revision as of 07:10, 27 April 2024
Hint: There are 2 distinctions - old appliances, and pure 240V systems - which used 3 wire plugs. The former is no longer allowed, and was replaced with a 4-wire plug
- This one has a ground and 2 hots on a modern appliance. With 3 wires, it means it has 240v only, but not 120v. [1]
- See Spruce for difference between 3 wire and 4 wire installation [2]
- But - older appliances which were 120/240v, not pure 240 - also had a 3-wire cord, and they combined ground with neutral. But that is no longer allowed as it appears to be less safe - for example if in a non-fault condition, the person has lower resistance than the ground. See [3]
- If you only have a 2 conductor + bare ground, mark the bare ground as a neutral and run it to the neutral of the subpanel if you want 240V/120V. It is not clear whether codes allow this. [4]
- Does a 3-wire 240v circuit have a grounded neutral, or a ground that is neutralized?
- Thus: is it safe to say that any 3-wire appliance is pure 240V no 120V?