# Parallel Windings



## cpotter (Jul 13, 2020)

Technical question here. Just picked up a Homelite EH4000HDC. 3600 running watts. The unit has a 240v plug, and two standard 120v plugs. Two hot windings, each feeding one of the 120v plugs (for 15A each) and each feeding one side of the 240V plug (for a total of 15A). Would it be possible, to connect the two hots in parallel, for a single 120V plug capable of 30A? (Ie replace the 240v plug that I'll never use, with a 30A 120V twist lock that I will use all the time)

Thanks
Chris


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## iowagold (Jan 22, 2020)

i am having a hard time finding your generator.
please check the numbers you posted.
is this an late model generator or an older model?
and is it inverter?


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## tabora (Sep 6, 2018)

cpotter said:


> Would it be possible, to connect the two hots in parallel, for a single 120V plug capable of 30A?


Not without some serious circuitry. Those two hots are 180 degrees out of phase so that they make 240V across them.


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## cpotter (Jul 13, 2020)

tabora said:


> Not without some serious circuitry. Those two hots are 180 degrees out of phase so that they make 240V across them.


Can you help me understand then, how some generators have a switch allowing you to have 120v max current, or less current but 120v and 240v at the same time?


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## cpotter (Jul 13, 2020)

iowagold said:


> i am having a hard time finding your generator.
> please check the numbers you posted.
> is this an late model generator or an older model?
> and is it inverter?


Try looking up Homelite EH4400. Same thing, ever so slightly larger. Its from 1990.


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## tabora (Sep 6, 2018)

cpotter said:


> Can you help me understand then, how some generators have a switch allowing you to have 120v max current, or less current but 120v and 240v at the same time?


Those generators would have the circuitry to realign the phases to parallel to a 120V 30A receptacle. It's similar to what is done when two 120V generators are paralleled to increase capacity.


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## cpotter (Jul 13, 2020)

tabora said:


> Those generators would have the circuitry to realign the phases to parallel to a 120V 30A receptacle. It's similar to what is done when two 120V generators are paralleled to increase capacity.


This is the wiring diagram for my generator. Followed by that of a Honda EM6000, which seems to be a similar setup however with a voltage selector switch. Nothing crazy to change phasing from what I can see. The owners manual simply states not to throw that switch with the unit running.


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## Melson (Dec 8, 2019)

re- read and *think about what tabora said in his post #3. Pay attention to the part about "out of phase".
Or, go ahead and try it.


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## cpotter (Jul 13, 2020)

Melson said:


> re- read and *think about what tabora said in his post #3. Pay attention to the part about "out of phase".
> Or, go ahead and try it.


Thank you so much, for your incredibly helpful comment. Great contribution to the discussion. I asked for help understanding how this works, not for your condescension.


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## motormonkey (Jul 10, 2016)

The wires labeled 3 and 14 are one of the 120 volt windings. The wires labeled 9 and 5 are the other 120 volt winding. Theoretically, for correct phasing for parallel operation, you would need to Isolate these four wires, connect wires 3 and 9 together, and connect wires 14 and 5 together. One of these wire pairs should be considered neutral and should bonded to ground for standalone operation. You would also need appropriate overcurrent protection, in addition to the appropriate 30 amp 120 volt receptacle.

This falls into the category of modifications contrary to the design intent of the generator's manufacturer. DO SO AT YOUR OWN RISK!


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## cpotter (Jul 13, 2020)

motormonkey said:


> The wires labeled 3 and 14 are one of the 120 volt windings. The wires labeled 9 and 5 are the other 120 volt winding. Theoretically, for correct phasing for parallel operation, you would need to Isolate these four wires, connect wires 3 and 9 together, and connect wires 14 and 5 together. You would also need appropriate overcurrent protection, in addition to the appropriate 30 amp 120 volt receptacle.
> 
> This falls into the category of modifications contrary to the design intent of the generator's manufacturer. DO SO AT YOUR OWN RISK!


This is what I was hoping for! Thank you very much. I need to take mine apart and see what the connections look like, and do a little more research first. But this is a huge help.


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## Marlin (May 25, 2015)

cpotter, if you notice on the schematic that you included of your generator, you can see that in the generator you have what looks like a primary transformer winding and two secondary transformer windings. If you look closely at the secondaries, you will see numbers representing the wires leading from the windings.

You will see that there are 4 wires, one being labeled #3, one is labeled #14, one is labeled #9 and the last one is labeled #5.

Your generator has two 120 volt output windings. They are connected in series so that you can get 240 volts out of your generator. Your generator provides a connection to the midpoint where those two windings are connected together, that point becomes effectively the neutral of the 120 volt outlet sockets.

As you can see, #14 and #9 are connected together. Together, they become effectively the midpoint between the two hot output wires, #3 and #5.

In operation, while #3 goes positive 120 volts compared to (9 and 14 together) your #5 is going negative compared to (9 and 14 together) by another 120 volts. Number 3 and number 5 are both exactly 120 volts away from the combination of 9 and 14, but, they are out of phase with each other, while one goes negative, the other goes positive.

Those voltages add together because the windings are in series with each other, so, the voltage between 3 and 5 is 240 volts.

Your generator is giving you two choices, you can connect a 120 volt load to one of the windings or the other, by choosing one or the other of the 120 volt output sockets. But, you cannot get the entire generator's output, only one half of the generator's output, because you can only connect to one winding at a time.

Now, to answer your question, if you could modify your generator, completely unhooking all four wires from the rest of the circuit, you could do this: Connect wires #3 and #9 together and label the combination L1 just for grins. Then, connect #14 and #5 together and again just for grins, label that connection as L2.

If you measure the voltage between the new L1 and L2 you will find your 120 volts and you will have the entire output of your generator available.

There were many, many generators built from the factory having a nice big switch on the front panel that could do exactly this for you.


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## Marlin (May 25, 2015)

I see that while I was typing my response that I just sent, there was another message, from motormonkey that explained the concept much more precisely than I did.

Did not mean to step on anybody, sorry about that.


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## cpotter (Jul 13, 2020)

Marlin said:


> cpotter, if you notice on the schematic that you included of your generator, you can see that in the generator you have what looks like a primary transformer winding and two secondary transformer windings. If you look closely at the secondaries, you will see numbers representing the wires leading from the windings.
> 
> You will see that there are 4 wires, one being labeled #3, one is labeled #14, one is labeled #9 and the last one is labeled #5.
> 
> ...


Thats sort of where I was going with the Honda above, having that switch. I have no use for the 240v output but I could certainly make use of 30A on one 120v circuit. Thank you very much for your help.


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## cpotter (Jul 13, 2020)

motormonkey said:


> The wires labeled 3 and 14 are one of the 120 volt windings. The wires labeled 9 and 5 are the other 120 volt winding. Theoretically, for correct phasing for parallel operation, you would need to Isolate these four wires, connect wires 3 and 9 together, and connect wires 14 and 5 together. One of these wire pairs should be considered neutral and should bonded to ground for standalone operation. You would also need appropriate overcurrent protection, in addition to the appropriate 30 amp 120 volt receptacle.
> 
> This falls into the category of modifications contrary to the design intent of the generator's manufacturer. DO SO AT YOUR OWN RISK!


Other question that I have, is how would you determine which side should be hot and which should be neutral? Thanks again.


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## Marlin (May 25, 2015)

Other question that I have, is how would you determine which side should be hot and which should be neutral? Thanks again.

Makes no difference at all, until you attach an outlet receptacle to the wires. It is at that point when you determine which is "Hot" and which is "Neutral". Whichever one you ground, the other becomes the hot. It is just like others have said, it is a mater of reference. If you were a bird, perched on the hot wire, to the bird it would appear that the ground is hot.


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