Dedicated Portable Generator Circuit


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Old 11-01-17, 05:23 AM
J
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Question Dedicated Portable Generator Circuit

Here in Rochester, NY I'd like to create an dedicated standalone portable generator circuit that would only be used to power our furnace and refrigerator in case of a power failure. It would be "off the grid", not connected to any existing home wiring. I have a Reliance 30 amp 4-wire L14-30 style power inlet, two 30A duplex outlets to mount, one near the furnace, one near the refrigerator. I have a coil of 10/2 solid Romex cable and a Reliance 10 gauge, 4 prong 30 amp twist lock generator cord. The twist lock generator cord will be plugged into the 120/220V generator outlet, however I only want 120V. My question is:

Using the 10/2 Romex what is the correct wiring to just have 120V current? In other words what do I do with the four connectors on the power inlet box?
Best Wishes and thank you for your patience!
 
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Old 11-01-17, 05:46 AM
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Short answer, yes with conditions.

1. Use a 15 or 20 amp inlet and 15 and/or 20 amp receptacles. Use a 120 volt 15 or 20 amp receptacle on the generator. (You could have more than one separate dedicated off grid circuit each with its own 120 volt inlet.)

or

2. Install a subpanel after the 30 amp inlet to accept the 4 wire 120/240 volt feed (10/3 Romex) and with 15 and/or 20 amp 120 volt branch circuits to 15 and 20 amp receptacles. (20 amp receptacles must be on 20 amp circuits.) Well, you could use 10/2 Romex leaving one of the hot prongs of the inlet unused and 120 volts only going to the subpanel

You may not have 30 amps coming into 15 or 20 amp receptacles. Ordinary 15 amp appliances and lights and equipment may not be plugged into circuits that could provide more than 20 amps. The plug on the power cord implies the appropriate amperage circuit for the appliance. Do not cut it off and substitute a plug of a different kind.
 

Last edited by AllanJ; 11-01-17 at 06:11 AM.
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Old 11-01-17, 07:02 AM
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It is better to have a balanced load on the generator so you really do want the 120/240 volt feed.
 
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Old 11-01-17, 07:37 AM
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How do you plan to connect the furnace? Most central heating and cooling equipment cannot be connected with a cord-and-plug as hardwiring is required.
 
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Old 11-01-17, 09:51 AM
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I would do this with the furnace circuit. Run the line from the panel into a box with double pole double throw switch (2 3 way switches ganged on the same toggle).

Connect the furnace (hot and neutral) to the common switch terminals (usually stained a dark color). Connect the panel feed (hot and neutral) to one set of side terminals. Connect a 15 amp inlet to the other set of side terminals. Now this switch will act as a transfer switch. Use an extension cord to connect this inlet to a (female)receptacle on the dedicated off-grid circuit.
 
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Old 11-02-17, 07:40 AM
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You folks are terrific, thank you for great advice, a lot to consider! Back to the original question though, which legs of the power inlet should be used for 120V only?
 
 

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