120V Single phase generator to 120/240v single phase panel.

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Nickhxc4life

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Richmond, VA
Hey guys,

Any way to safely do this? I would use an interlock kit to make sure I'm not back feeding the grid. i do not want or need to run any 240V appliances. Those breakers would be off. My generator is a 6000watt 120V single phase. It has 2 15amp receptacles and one 30amp twist lock receptacle. I'm well aware that a 120/240V generator would be ideal but I got too good of a deal on this one and anything I can do has to be safer than multiple extension cords running through the house. I'd like any input on using a manual transfer panel as well as feeding directly to my main panel. Again, I plan to use the NEC required interlock if I do not use the manual transfer panel. Is it easier or safer to just feed one bus of the main panel? Looking for any and all ideas and thoughts.
 
Never heard of that. So the 30 amp twistlock is 120 volts, too? If your main is off and your 240 volt breakers are off. I suppose it would work. IMHO I don't think it would be code compliant because of the 240 volt breakers, even if they're off.
 
Can't hurt anything. Even if the 240 breakers were on, they would see 0V between the poles, and the equipment wouldn't work.

Pretty sure I've heard of "120V panels" where the busses were purposely both fed with the same phase and all breakers were single-pole.
 
MAC702 said:
Can't hurt anything. Even if the 240 breakers were on, they would see 0V between the poles, and the equipment wouldn't work.

Pretty sure I've heard of "120V panels" where the busses were purposely both fed with the same phase and all breakers were single-pole.
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If the breaker to the water heater was on. I think you would have some power on the other phase.
 
Well my extension coords are the proper gauge for the run to avoid voltage drop but it's a hassle. Right now I have to get out the gen, run the main cords to the house, plug in what i need, go back outside, fire it up, and flip on the receptacles on the gen. Not to mention it runs through a window on the lower level of my house so my home is no longer secure. I want to wire it as it a proper 240V 30amp feed we're coming from the genset so a 30amp 240V female receptacle in a weather proof, in use rated enclosure. It just wouldn't be getting a true 240V until I can buy a different generator. Right now it takes me about 30-40 minutes to get up and runing with extension cords. It's also a hassle getting a feed to my second level.

Also, water heater is gas. Only 240V appliances are outdoor condensing unit, dryer, and stove.

We are subject to bad hurricane and winter damage. Typically when we lose power it is off for a at least 24 hours but often longer.
 
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Nickhxc4life said:
Also, water heater is gas. Only 240V appliances are outdoor condensing unit, dryer, and stove.

We are subject to bad hurricane and winter damage. Typically when we lose power it is off for a at least 24 hours but often longer.
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PHP:

Yeah, just don't turn the stove on. Otherwise you'll feed the other phase.

.
 
Nick, you just happen to be in my home town! Welcome!

I would do a complete 120/240v 30a inlet and feeder to the panel and put in a 2p interlocked generator breaker. This way, you'll be ready for a 120/240v generator in the future.

For now, just join both terminals of the generator breaker with, say, the black feeder conductor, capping the red in the panel. Make a cord to fit the inlet, but with a 120v male end.

When you do get a 120/240v generator, all you have to do is replace the 120v 30a male end with a 120/240v 30a male end, and connect the unused-for-now red cord conductor.

This will allow you to energize all of your 1p (120v) circuits (within the 30a limit of your installation and generator, of course) and the 2p (240v) circuits will simply not work.
 
Larry, If I fed via a 120V plug wouldn't I only be feeding only the A or B side of the panel? Also, not sure why but I was under assumption that I could damage the dryer or condenser unit if either tried to run while on the gen if my wife accidentally tried to turn either on....? Is that incorrect? the appliances would not see full 240 but they could still try to run...sorry I mostly deal with commercial 277/480 3phase and medium voltage.
 
Nickhxc4life said:
Larry, If I fed via a 120V plug wouldn't I only be feeding only the A or B side of the panel? Also, not sure why but I was under assumption that I could damage the dryer or condenser unit if either tried to run while on the gen if my wife accidentally tried to turn either on....? Is that incorrect? the appliances would not see full 240 but they could still try to run...sorry I mostly deal with commercial 277/480 3phase and medium voltage.
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Yes, if powering the panel by backfeeding a single-pole receptacle, you'd only be feeding one buss in the panel, and therefore only have half of your 120V loads powered. And now you'd definitely have some issues if you used your 240V equipment.

But if you do feed both panels with the same 120V...

While you should just turn 240V loads off at the breaker, of course, I just saying that I don't see any damage if the breakers were on. They wouldn't "see full 240" because they would see 0. FWIW, while my first trade is electrical, I've been doing mostly HVAC repair for the last 10 years.

For those familiar with large RV's, is this how they are set up? When you have the full NEMA 14-50 receptacle available, you plug in your 14-50 plug directly, and have 120/240 to your RV panel. But when only a 5-15, 5-20, or non-NEMA 30A RV receptacle is available, you use the adapter that puts the same hot onto both of the hots of your 14-50 plug. Granted, it might be that large RVs don't have 240V loads, but just use two busses to balance the 120V loads.

On the range and dryer, you'd have 120V controls and lights, even a motor on the dryer, but no 240V heating.
 
Nickhxc4life said:
Larry, If I fed via a 120V plug wouldn't I only be feeding only the A or B side of the panel? Also, not sure why but I was under assumption that I could damage the dryer or condenser unit if either tried to run while on the gen if my wife accidentally tried to turn either on....? Is that incorrect? the appliances would not see full 240 but they could still try to run...sorry I mostly deal with commercial 277/480 3phase and medium voltage.
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I am suggesting feeding power to both A AND B sides, using a pair of pigtails to feed both poles of the backfed breaker. To only supply one side would actually be more likely to feed 120v to a load expecting 240v.

Supplying power to both hots of any 240v appliance whose breaker you leave on would energize any line-to-neutral portion of that appliance, such as the light and clock/timer of a range or dryer, but would have absolutely no effect on the line-to-line portion, like a heating element, or a water heater. You could actually air-dry your clothes.

You are familiar with Interlockkit in Richmond, near The Diamond, aren't you? https://www.interlockkit.com/ Feel free to message me for my number if you'd like to call me.
 
(Multiwire circuits might pose a hazard here... I get no search hits on words "multiwire", "share", or "neutral" so I believe this wasn't considered in this thread)

I just came across this thread. The problem I see with even temporarily feeding both phases of a 240V panel from a 120V/30A generator or other source is (dreaded?) multiwire circuits. Think about a 15A multiwire branch... Two 15A breakers feeding two ungrounded conductors (2 hots) but sharing the grounded conductor (1 neutral). That has the potential to put 30A through the 14ga neutral, and all the breakers would be happy while the wire cooked. It seems to me the generator output should be no larger than the smallest multiwire breaker.

I've used this hookup successfully with 20A multiwire circuits in my panel, but using a 2200W rated 120V generator with output limited by a 20A internal breaker.

Anybody else see it this way?

Ray
 
Rayb said:
(Multiwire circuits might pose a hazard here... I get no search hits on words "multiwire", "share", or "neutral" so I believe this wasn't considered in this thread)

I just came across this thread. The problem I see with even temporarily feeding both phases of a 240V panel from a 120V/30A generator or other source is (dreaded?) multiwire circuits. Think about a 15A multiwire branch... Two 15A breakers feeding two ungrounded conductors (2 hots) but sharing the grounded conductor (1 neutral). That has the potential to put 30A through the 14ga neutral, and all the breakers would be happy while the wire cooked. It seems to me the generator output should be no larger than the smallest multiwire breaker.

I've used this hookup successfully with 20A multiwire circuits in my panel, but using a 2200W rated 120V generator with output limited by a 20A internal breaker.

Anybody else see it this way?

Ray
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Yes it can potentially overload neutral of a MWBC. Seems that it isn't too likely it will be more than 30 amp available either though nor too likely you have that much load all on one circuit while running such a small generator for standby, if you do probably not for very long at all- exception would be if you are trying to run electric space heaters, but they are going to draw enough that you won't be running anything else at same time or you are likely tripping 30 amp breaker on the genset. Still worth some consideration though. Most any genset over 3600 watts is probably going to have 120/240 capability.
 
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