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4/1/2020 4:14:10 PM
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Posted: 1/8/2005 3:57:45 AM EDT
Just curious if all outputs from 1 generator are in phase. Lets say you have 2 120 volt 15 amp outputs, would it be possible to strap them onto 1 input?
Yes, I know its not the best way to do it, I know theres better ways. But, I have to work with what I have and right now thats about the only solution. Once time and money permit I'll move to a better solution, but for now I simply need to know, are outputs strappable from 1 generator?
Thanks
Link Posted: 1/8/2005 5:24:31 AM EDT
[Last Edit: 1/8/2005 5:44:16 AM EDT by Waldo]
I just woke up and haven't had my coffee yet.


 Are you trying to get 220V out of a home genset that only has 110V?


 
Link Posted: 1/8/2005 6:09:50 AM EDT

Originally Posted By Waldo:
I just woke up and haven't had my coffee yet.


 Are you trying to get 220V out of a home genset that only has 110V?


 



No, I'm trying to double the amperage by strapping 2 110 15 amp outputs together to get a 110 30 amp.
Link Posted: 1/8/2005 6:24:42 AM EDT


I still don't quite follow, but I don't think it will do what you want.
Link Posted: 1/8/2005 6:30:45 AM EDT
Not without synchonizing and control equipment.  That is way above the price range of consumer grade generating sets.

One problem is getting the phases to line up and come on line.  If one phase lags by a bit, that generator will not pick up the load - kind of like a plow horse one foot behind his neighbor.  

We did not have this equipment for our 700 kw generators.  
Link Posted: 1/8/2005 6:31:09 AM EDT
If it isn't a 3000 watt generator, you cannot get there from here.
Link Posted: 1/8/2005 9:42:58 AM EDT
one way to find out,

Hey yall watch this!
real­ly though, don't try it, wouldn't want something to happen to you
Link Posted: 1/8/2005 9:44:21 AM EDT
As Pogo mentioned, getting both generators to run at exactly the same speed and "timed" so that the AC voltage from both of them rises and falls at exactly the same instant is very hard to do. If you don't get it right, each generator looks like a short circuit to the other – Can easily damage them.

Also, even if you manage to get them synched up, they still have a tendency to share the load unequally – one works itself to death while the other one just loafs along.

However, Honda makes several small "Inverter" generators that can be strapped together for higher power output. These models use a DC generator and an inverter to convert DC to AC power. Since the inverter is electronically-controlled, it becomes much easier to syncronize the AC waveform, share the power, etc. between several identical generators.  Yamaha also makes some inverter models, although I'm not sure if they have strapping capability.
Link Posted: 1/8/2005 10:07:18 AM EDT
[Last Edit: 1/8/2005 10:21:08 AM EDT by JB69]
(Electrician chiming in)


If you're talking about connecting together two 15A outputs on the SAME generator....

ie. you have two plugs on the generator, and want ONE 30A feed instead....


Answer is no.........  You will smoke your generator, more often than not, depending on how the actual coils are wired/connected, and without an oscilliscope or a phase identifier, you'll have no way of finding out for sure........ I don't recommend trying this at all.......


Good luck doing it EVER with two generators, without very expensive equipment to synchronize the phases.....   This is only done in large commercial/industrial applications, if ever.


BTW, this is why most generators have a 240V 30A output as well.  So you can use that to feed a transfer switch and power up your house wiring, when the electricity goes out.


My question is WHY do you need a 30A 120V output at all ? Thats a substantial amount of amperage at  only 120 Volts.....  Very uncommon to need that much for any single application.

I'm assuming this isn't just for some lights and a few things to run, when your power goes out ?


Probably not the answer you were hoping for.... sorry


JB


Link Posted: 1/8/2005 10:19:33 AM EDT
[Last Edit: 1/8/2005 11:01:16 AM EDT by JB69]

Originally Posted By wildearp:
If it isn't a 3000 watt generator, you cannot get there from here.




Not to be an Electrical Nazi or anything but your math is a little bit off there.

Ohms law....  Power (Watts) = Current (Amps) X Electromotive Force (volts)

                                                  P = I x E     haha, love that formula !


Anyways.... at 115 Volts, and a 30 A current needed, you would get 3450 Watts...  ( a 3500 W generator)

The math is 'sort of' variable, since the accepted "standard voltages" are 110, 115, and 120..  Alll being the same thing.... house voltage.


so this wattage rating can run the range of  3300 Watts ( Using 110V )  to 3450 Watts ( Using 115 Volts ) all the way up to 3600 Watts ( Using 120 V )

This is where the ratings on some generators can get confusing, and people think they're getting ripped off, etc....... All depends on what actual voltage is being used to rate the power output.   Also some generators will produce slightly higher OR lower voltage, depending on design of the coil windings........


Really just nit-picking, but thought I'd toss this out there for anyone who's ever been confused by this, and wondered about how it works.....


JB



Link Posted: 1/8/2005 4:59:42 PM EDT
Thanks guys, thats what I figured.
It is only 1 generator, I know strapping 2 (Besides Honda) would be a MAJOR pain in the ass without quite a bit of work.
Reason is, I have a 4000 watt Generac. In order to sufficiently power my house I need to backfeed through an outlet. Only way to run my furnace at this point should the power go out. So, I wanted to take 1 of the outputs and run it to an outlet, and another of the outputs and run it to a different outlet and backfeed power to my house that way since I dont yet have a transfer switch. Hence 120 volts 30 amps. Each output is 15 amp, if I ran both outputs it'd be (theoretically) 30 amps at 120 volts. I didnt know if the outputs were in phase or not though. I thought they might be since it was all 1 unit, but then figured with my luck it wouldnt be.
As I said, I know its not the best way, but its all i have at this time. I have 2 20 amp outlets in the garage, so backfeeding wouldnt be a problem, plug 1 output into an outlet, another output into another outlet and let the generator do its thing.
Guess that wont work after all.
Link Posted: 1/8/2005 5:15:20 PM EDT
Whoa, talk about completely misunderstanding your original question!

Most generators that produce both 120 and 240 volts AC have two windings, each of which produces 120 volts. Since the voltage between them measures 240 volts (and not zero volts), you can't strap them together.

You've stumbled on the difference between a cheap generator and a not-so-cheap generator: The cheap one has two 120-volt windings, each of which is capable of only supplying half of the generator's maximum rated output. The not-so-cheap one also has two windings, but one of them is beefy enough to supply the generator's entire rated output on one 120 volt leg.

BTW, if your Generac is a 4000XL or 4000EXL model, it falls in the not-so-cheap category: The full 4000 watts is available on the 120 volt twist-lock connector. The hard part is finding a mating connector in your house that's also capable of carrying 4000 watts!
Link Posted: 1/8/2005 5:33:35 PM EDT
[Last Edit: 1/8/2005 5:35:28 PM EDT by Ky_Bob]
This may not be up to code but it works.

Install an outlet in line with the power source of your furnace. Install a pull out disconnect in line with the same power source but between the source and the outlet you just installed. The pull out is commonly found on the outside units of cental air conditioners. You simply pull it out and it breaks both sides of the circuit.

This configuration will keep stray voltage from running around the circuits in your house when back feeding.

Now, the electric goes out, you go down to the furnace, the pull out, and the outlet. they should all be in the same area. Pull the disconnect, plug your generator output into the outlet and your furnace will run. Make sure the thermostat is on the same circuit as well.

IF anyone tries this at home, you are on your own.
I accept NO liability for what YOU do.

Bob
Link Posted: 1/8/2005 5:43:09 PM EDT
Transfer switches are about 60 bucks.  Get one and have your critical circuits run to it.

Don't do the backfeed setup.  It is dangerous and you will be lucky if you only start a fire.

Unless you are trying to run resistance heat strips, a 220/240 output from your genset should handle critical circuits.

Link Posted: 1/8/2005 6:07:39 PM EDT

Originally Posted By ar-wrench:
Transfer switches are about 60 bucks.  Get one and have your critical circuits run to it.

Don't do the backfeed setup.  It is dangerous and you will be lucky if you only start a fire.

Unless you are trying to run resistance heat strips, a 220/240 output from your genset should handle critical circuits.




I havent found a transfer switch for under about 300. But its the wall mounted 6 circuit ones.
Wheres a good place to get a good, reasonably priced transfer switch?
Link Posted: 1/8/2005 6:08:14 PM EDT

Originally Posted By Skibane:
Whoa, talk about completely misunderstanding your original question!

Most generators that produce both 120 and 240 volts AC have two windings, each of which produces 120 volts. Since the voltage between them measures 240 volts (and not zero volts), you can't strap them together.

You've stumbled on the difference between a cheap generator and a not-so-cheap generator: The cheap one has two 120-volt windings, each of which is capable of only supplying half of the generator's maximum rated output. The not-so-cheap one also has two windings, but one of them is beefy enough to supply the generator's entire rated output on one 120 volt leg.

BTW, if your Generac is a 4000XL or 4000EXL model, it falls in the not-so-cheap category: The full 4000 watts is available on the 120 volt twist-lock connector. The hard part is finding a mating connector in your house that's also capable of carrying 4000 watts!



Its the EXL.
Link Posted: 1/8/2005 7:16:05 PM EDT

Originally Posted By Specop_007:
Wheres a good place to get a good, reasonably priced transfer switch?



Ebay.
Link Posted: 1/9/2005 5:18:55 AM EDT

Originally Posted By Specop_007:

Originally Posted By ar-wrench:
Transfer switches are about 60 bucks.  Get one and have your critical circuits run to it.

Don't do the backfeed setup.  It is dangerous and you will be lucky if you only start a fire.

Unless you are trying to run resistance heat strips, a 220/240 output from your genset should handle critical circuits.




I havent found a transfer switch for under about 300. But its the wall mounted 6 circuit ones.
Wheres a good place to get a good, reasonably priced transfer switch?



Home depot sells both a 30 amp and a 60 amp Square D transfer switch.  I sold about 20 of them on ebay pre rollover

I haven't bought one in several years, but can probably find one for you if you can't locate one.
Link Posted: 1/9/2005 5:33:33 AM EDT
Link Posted: 1/9/2005 5:44:13 AM EDT

Originally Posted By ar-wrench:

Originally Posted By Specop_007:

Originally Posted By ar-wrench:
Transfer switches are about 60 bucks.  Get one and have your critical circuits run to it.

Don't do the backfeed setup.  It is dangerous and you will be lucky if you only start a fire.

Unless you are trying to run resistance heat strips, a 220/240 output from your genset should handle critical circuits.




I havent found a transfer switch for under about 300. But its the wall mounted 6 circuit ones.
Wheres a good place to get a good, reasonably priced transfer switch?



Home depot sells both a 30 amp and a 60 amp Square D transfer switch.  I sold about 20 of them on ebay pre rollover

I haven't bought one in several years, but can probably find one for you if you can't locate one.



Appreciate the offer but found what I need on Ebay.
Now, if you wana come install it for me we can talk business....
Link Posted: 1/9/2005 6:07:41 AM EDT
[Last Edit: 1/9/2005 6:07:48 AM EDT by 7]
I bought a Generac 6 switch transfer switch from ebay and just recently had it wired up.  Here are a few photos.

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