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I have a 35KW Wacker diesel generator. It has 3 x 240V 3 prong - 10, 20 and 30 amp service. it also has a 4 wire 3 prong 125/250 locking (center ground) outlets of 50 amp.

My question is how do I connect that to my 20K transfer switch (240V 4 prong) inlet. At 50 amps, the most I can get out of 240V is 12KW, right? I'm thinking to rewire the generator with 100 amp service - is that feasible. I need the whole 20KW to drive our electrical needs. Peak is actually a bit more than that...

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    At 35kw the generator should be able to supply ~145 amps the question is this the peak load of the generator? I would think it should be able to provide 100a but cord and cap for the most part are limited to 30a this is probably why it is wired this way. A permanent wiring method would allow for the larger wiring you need. – Ed Beal Sep 19 '16 at 7:54
  • Would using a suitably rated pin and sleeve connector and inlet pair be an option for such a fat hookup? (NEMA plugs being limited to 50A as they are) – ThreePhaseEel Dec 10 '16 at 5:09
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For a generator of that size, the primary connection would not be through those convenience outlets, but rather directly to lugs sized for the cables required. If this wasn't the primary use of the generator, and you wanted an easily detachable connection, and 50 amps was sufficient, then you could use the 4-conductor receptacle with a cable.

Your model sounds like the G50. See page 34 of that manual:

3.13 Connection Lugs

See Graphic: wc_gr002611

The customer connection lugs (r) are located on left at the bottom of the panel behind a hinged door. The lugs provide connection points for attachment of outside loads. A large label like the one shown in section Terminal Connections is attached to the inside of the terminal door. It shows the correct terminal connections for selected voltages. Connections to the lugs should be made by running the power cables up under the lug door in the bottom of the panel and into the lug. Use a 3/8 in. Allen wrench to tighten cable connections in place.

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I'm confused as I thought all 240 volts had 4 prongs. I'm thinking you may be receiving power from one power leg rather than both, something to look into. If you get the correct connector straight, you may want to consider an Interlock rather than a transfer switch. I originally was going with a Transfer Switch but decided on an Interlock. With a simple Interlock device, you power whatever you wish in your breaker panel by turning the breakers on, careful not to overload the generator, plus it's less expensive. The Interlock prohibits you from having the Main Breaker on when generator is on. With Transfer Switch, you power only the selected breakers that are wired to it. Lastly, when running 240 volts, the generator should be balanced, that is, not excessive wattage on one power leg versus the other. Just bought a watt meter to help with the balance, and the watt meters are also available at Reliance. I got the one for 30 amps and couldn't locate one any place else. Special order for exterior use but mine was shipped same day ordered.

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  • There is lots of good stuff here, but it doesn't really answer the question the OP asked.... – ThreePhaseEel Oct 4 '19 at 23:20

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