generator to transfer switch plugs

Old 08-06-02, 01:47 PM
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Question generator to transfer switch plugs

I have a problem connecting my generator to a new transfer switch i installed in my home. The 240 outlet on my generator is three prong but the plug into the transfer switch is 4 prong. Can someone please tell me what to do with the 4th wire on the generator side? The wattage or the generator is perfect for the transfer switch so there is no problem there. Its just that the instructions don't mention a word about this connection. Thanx
Old 08-06-02, 02:49 PM
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I believe posting in the electrical forum will allow more experienced electricians then me to give you a perhaps better answer. I would say that the three prong plug has 2 hots and one neutral wire, while the 4 prong one will add a ground. Since a portable generator is not grounded anyway, I would use a three prong plug on the generator side, use a 4 prong on the panel side, and use a three wire cable.
Old 08-10-02, 12:54 PM
Gary Tait
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You need to get a 120/240 outlet installed on your generator,
or replace it with one that has the 4 prong 120/240 recptical you

The 240 outlet you have there is 240V only.

If your generator now has two separate 120V receptacles,
with both sharing the same neutral but an opposite hot,
you could make a break in cable, but you would be limited to
15A per, and may be against code.
Old 08-11-02, 12:51 AM
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Generator to Transfer Switch

Hey Gary,

Thanx so much for your input. I apologize for not including all pertinent information in my original question... The generator has a total of three connectors:

1. One duplex 20 ampere 120V NEMA (GFCI) 5-20 parallel slot, V-ground receptacle.
2. One locking type 30 ampere 120V NEMA L5-30R receptacle.
3. One locking type 20 ampere 240V NEMA L6-20 receptacle.

It has an up and down switch: When the switch is in the 120V (up) position, you can take up full rated power at 120V from the single duplex receptacle, single locking type 120V receptacle, or a combination of these receptacles as long as the total load does not exceed the generating set capacity. (max. output is 5500 watts, continuous output is 5000 watts).

When the switch is in the 240V (down) position, you can take up to half of the rated power of the generating set at 120V from the duplex receptacle and up to half of the rated power of the set at 120V from the locking type 120V receptacle; or full rated power at 240V from the locking type 240V receptacle.

When the switch is at the 120V position, the locking type 240V receptacle cannot be used.

I would rather not change any plugs on the generator set (which btw is a Multiquip 6HZR) The transfer switch came in a Coleman Powermate box but the unit says its a GENTRAN model# 20216. It has 6 circuits and is rated to 5000 watts. Inbedded in the face of the unit is a 20 ampere 120V/240V with grounding plug. The instructions (which are littered with typos throughout) lists it as a NEMA CONFIG L1420R.

I hope I covered enough info so as to quelch any doubt in what I have going on here. Thank you very much for your time!
Old 08-18-02, 02:00 PM
Gary Tait
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Yuo HAVEto get a 120/240V recptacle somehow, and with your current setuop, is seems you cannot, at least safely.

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