# Possible To Connect 30 AMP Generator To 50 AMP Plug (Residential Transfer Switch)?



## camdiy (Dec 9, 2015)

I own the Honda EU2000 and EU2000i companion generators. The companion generator has a 30 AMP female plug which I usually connect to my RV. These two generators run in parallel. 

I am building a home and my electrician installed a manual transfer switch and what I believe is a 50 AMP female plug (4 prong). Can I connect my 30 AMP generator (when running in parallel) to my 50 AMP plug installed on my house without blowing up my generator or anything inside my house? Obviously I couldn't power up my entire house but thinking I should at least be able to run the furnance, refrigerator, etc.

What cable do I purchase? I don't see a 30 AMP male to 50 AMP male cable.


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## joed (Mar 13, 2005)

That generator appears only be 120 volt. I can't tell if that changes in the companion mode but I didn't see anything stating that it did. Connecting that to your panel would only power half of the circuits.
Assuming the generator has its own built in breaker, then there is no chance of damaging the generator. You would only trip the breaker if you tried to use too much power.


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## MrElectricianTV (Nov 13, 2014)

camdiy said:


> I own the Honda EU2000 and EU2000i companion generators. The companion generator has a 30 AMP female plug which I usually connect to my RV. These two generators run in parallel.
> 
> I am building a home and my electrician installed a manual transfer switch and what I believe is a 50 AMP female plug (4 prong). Can I connect my 30 AMP generator (when running in parallel) to my 50 AMP plug installed on my house without blowing up my generator or anything inside my house? Obviously I couldn't power up my entire house but thinking I should at least be able to run the furnance, refrigerator, etc.
> 
> What cable do I purchase? I don't see a 30 AMP male to 50 AMP male cable.


If you cannot find an adapter you can make one. Just buy the proper ends and some 10/4 (Includes ground) SO cord.

As Joed said, the circuit breaker on the generator will protect it from being overloaded.


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## Oso954 (Jun 23, 2012)

> what I believe is a 50 AMP female plug (4 prong)


If that is a normal female receptacle, you do not want to use that to backfeed. Doing so would require a double male cord which is extremely dangerous. (The double male cord is also known as a suicide cord.)

You need a recessed male inlet so you can plug a female cord end into it.


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## AllanJ (Nov 24, 2007)

The transfer switch should be wired to a male receptacle, sized for y our generator but for no more amperes than the tranfer switch is rated for. (All plugs and all receptacles imply a maximum amperage rating for each.)

If you might use more than one generator (one at a time) the male receptacle on the wall would normally be to match the larger generator. You can make an extension cord with female end that fits onto the male receptacle (e.g. 50 amp) and lesser amperage (male) plug (e.g. 30 amp) to connect to the generator. Not the other way 'round e.g. with a 30 amp female end and a 50 amp plug without a box (with a breaker, here, 30 amp, inside) in between.

You may not connect a generator to any of the usual (female) receptacles (wall plugs) about the house.

The wiring used to connect the generator to the home electrical system cannot act as a branch circuit or feed for other things except for loads not eligible to receive utility power and where that wiring is connected to a transfer switch or interlock in order to interface with the service panel.


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## jimn (Nov 13, 2010)

Those are 120 volt generators. I am willing to bet that 50 amp transfer switch is expecting 240 volts . I am not an electrician and can't speak to the safety of trying to feed the opposite sides of a split bus panel from two different power sources. Kind of makes be a bit nervous. 30 Amps at 120 volts won't power much. I think with this setup I would play the game of extension cords as you will have very few loads anyway.


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## Oso954 (Jun 23, 2012)

Feeding half the panel with 120V is not a problem, if done correctly. They will have to make sure that any 120V load they want to power is on that side of the panel. May have to swap some circuits around to do it.

The situation is a bit tighter than 30 amps at 120V. The two generators are only rated at 26.6 amps total. Operation above that level for prolonged periods will shorten the life of the generators. 
(Each generator is 1600 watts with a 2000W max for starting surges)


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## Speedy Petey (Feb 1, 2004)

camdiy said:


> What cable do I purchase? I don't see a 30 AMP *male to* 50 AMP *male cable*.


PLEASE DO NOT tell me your "electrician" installed a female receptacle to backfeed your transfer switch!! If so he is NOT an electrician and is a dangerous hack.

As stated, you need a MALE (pronged) inlet to feed from the generator to the transfer switch.


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## Toller (Jan 2, 2013)

Oso954 said:


> Feeding half the panel with 120V is not a problem, if done correctly. They will have to make sure that any 120V load they want to power is on that side of the panel. May have to swap some circuits around to do it.
> 
> The situation is a bit tighter than 30 amps at 120V. The two generators are only rated at 26.6 amps total. Operation above that level for prolonged periods will shorten the life of the generators.
> (Each generator is 1600 watts with a 2000W max for starting surges)


I ran my furnace, refrigerator, freezer, computer, television and few lamps off 1 EU2000 for a week on two occasions. The generator tripped once; presumably two things tried to turn on at the same time. Didn't do it any harm.

OP I wired the cord I used to plug the generator into the generator inlet with a 50a plug wired so that the 120 went to both sides of the transfer switch. Obviously I had no 240v circuits on it.


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## AllanJ (Nov 24, 2007)

> Please do not tell me that your "electrician" dada dada


For those of you eavesdropping who do not know what a male wall plug (inlet) looks like, it has exposed metal prongs like an ordinary (male) cord cap. The prongs are almost always recessed a little but are not meant to be out of the reach of one's fingers. They are not required to be covered when not in use except when outdoors and then a hinged weathertight cover is required. When this wall plug is properly wired (to a transfer switch or panel interlock arrangement), it will never be energized from behind. It will only be energized when the female end of an (energized) extension cord is fitted over it and then the prongs will be safely covered.

There is a caveat regarding feeding both legs of a (120/240 volt) panel with a single 120 volt generator or source. Neutrals of multiwire branch circuits (if any) can be overloaded depending on what loads are plugged in about the house and turned on.

When a single 120 volt source feeds the panel, an MWBC neutral carries the sum of the currents on the two halves (red and black if you insist) of the MWBC.


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## Tom738 (Jun 1, 2010)

Great point on the MWBC. You really have to know what you're doing to start using a generator that way.


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## Oso954 (Jun 23, 2012)

This was also a key point.


> *When this wall plug is properly wired *(to a transfer switch or panel interlock arrangement), it will never be energized from behind.


But it is not always done properly, so always test one that you are not sure of.


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