I have a need to run a small planer (Ridgid TP1300) and a 2hp, 220v dust collector off my generator. The generator is 4000 running watts and has a pair of standard 120v outlets which I can plug the planer into, but the dust collector may pose a problem. It has a standard straight-blade 3-wire 15-amp 220V plug (NEMA 6-15) and the receptacle on the generator is a 4-wire, 20-amp, 120/250V twist-lock (NEMA L14-20R). How do I make these two speak to each other? I was thinking of a 6-10′ long “extension cord” that would actually convert one to the other, but I don’t know how to make a 3-wire into a 4-wire?
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I'll start by saying that I don't think you stand a chance of running both of those loads with a 4000W generator. But if you can, here goes:
The reason why the generator has the four plug version is so that you can run either 120V or 240V loads. There are 120 volts between either hot (red or black) and the neutral (white), and there are 240 volts between the two hots.
You could make an extension cord that ignores the neutral. Start with a piece of 12 gauge three-wire SOW (cabtire). It should have red, black, and green conductors.
You'll need a male four-prong plug at the generator end. Connect the red and black conductors to the bronze colored terminals. Ignore the shiny silver terminal (for the neutral).
At the load end you'll need a female three-prong plug. Connect the red and black conductors to the bronze colored terminals. There will be no silver terminal for the neutral.
Be aware that your overcurrent protection doesn't exactly match up. Use at your own risk. You are protecting a 15A load with a 20A breaker.
Edited 11/27/2009 1:13 pm by Scott