looking for generator information

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  #1  
Old 01-03-13, 07:38 PM
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looking for generator information

Hi, I am trying to understand my home backup generator and need some help.

I have a Black Max Powermate Model PMO435252. It states on the ID and spec tag that it is 120/240 Volt. and is single phase. It has two duplex 120 volt receptacles and a L14-20 receptacle labeled 20amp 125/250 volt.

Does this generator have the ability to provide 220 volt to a well pump or electric hot water heater?

any help appreciated!
 
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  #2  
Old 01-03-13, 07:42 PM
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Yes you generator will run a 240 volt well pump. Look at motor tag to determine the current draw of pump.
Probably not an elecric water heater as they normally draw 4500 watts.
Also...check out this thread.
http://www.doityourself.com/forum/el...generator.html
 
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Old 01-03-13, 07:47 PM
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Your generator will supply up to 20 amps at either 120 or 240 volts.
 
  #4  
Old 01-03-13, 07:51 PM
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PJMax, thanks for getting back to me. I guess what I dont get is how can that L14-20 plug supply both 120 and 240 volts?

an extension cord came with the unit that plugs into the L14-20 receptacle and it has a 4 plug female end that provides 4 120 v output.

how do you get the 220?
 
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Old 01-03-13, 07:54 PM
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Its only a 5000 watt gen I think, so you will have to determine what the loads are. Most water heaters are 4500 watts to your be maxed. The well pump I doubt it will start it. Need to post the ratings.

Then you have the whole issue of getting the gen wired to these appliances. Need a transfer switch wired to the panel.

Hope this helps.

Something like this.


 
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Old 01-03-13, 08:04 PM
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your right about the load issue, I would have to check the motor ratings if I can find the paperwork. (the pump is 130ft. down)

I still would like to know how you draw 220 out of that L14-20 connector.
I am a little weak in understanding 220volt anyway.

For instance, I know the electric dryer has two hot wires, a neutral and a ground. The hot water heater only has two wires and a ground?
 
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Old 01-03-13, 08:06 PM
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The water heater needs two hots and a ground.

The four prong receptacle has two hots at 120, a neutral, and a ground.
 
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Old 01-03-13, 08:15 PM
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lawrosa, nice picture, you draw well?

pcboss: so if I follow, the two hots that leave the 4 prong receptacle could be wired to a 220 appliance and provide the 220 volt?

what is the difference between the dryer using 2 hots, a neutral and a ground, and the hot water heater that uses 2 hots and a ground? ie. why no neutral used?
 
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Old 01-03-13, 09:50 PM
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so if I follow, the two hots that leave the 4 prong receptacle could be wired to
a 220 appliance and provide the 220 volt?
Yes.....that is correct......except that it is 240 volts not 220


what is the difference between the dryer using 2 hots, a neutral and a ground, and the
hot water heater that uses 2 hots and a ground? ie. why no neutral used?
A water heater simply has 240 volt heating elements to power.....nothing else.

A dryer also has 240 volt heating elements.....but in addition.....it needs 120 volts for
the control circuits, motor, drum lamp etc.....which is why it needs the neutral.


.
 
  #10  
Old 01-04-13, 05:36 AM
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I suspect, as lawrosa said, that your generator will not even start the well pump. Starting current for an ac motor can be as much as ten times the running current. That is my limiting factor in speccing a standby generator for my house - the well is 750 feet deep.
 
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Old 01-04-13, 08:35 AM
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md2...you may be right, i understand that breakers are designed to hold more than there rating at start-up. I guess I could rig up a test by wiring the well pump to the generator and see.

the hot water heater has two 4500 watt heating elements. the generator has 5250 running watt capacity. what if one heating element was disabled? would that help?
 
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Old 01-04-13, 08:48 AM
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Only one element runs at a time on the HWH. They are not on at the same time.

You would be close to maxed out running the HWH and will not be able to run much else. A light or two...etc.

Like I said about the well pump, look in the control box. It should list the amps. Be careful...High voltage in there, Should be by the well tank....
 
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Old 01-04-13, 09:11 AM
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Lawrosa, the control box has a 30 amp rating stamped on it with a statement about having to install delay type fuses for startup. so that seems to confirm what your saying.....that dog wont hunt.....and that pump wont run with this generator.

as far as hot water......its not essential, obviously, a luxury in a no power situation.

we have city water now, it used to be all well. I had hoped in a circumstance of possible no city water, the well would run. we do have a 1000 gallon holding tank with a coyote system that runs on 120, so we should have a 1000 gallon reserve.

thanks much for your help!
 
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Old 01-04-13, 09:43 AM
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i understand that breakers are designed to hold more than there rating at start-up. I guess I could rig up a test by wiring the well pump to the generator and see.
The question is "What is the maximum current rating of the generator?" The answer should be in the owner's manual, if not on the nameplate on the generator.

the hot water heater has two 4500 watt heating elements. the generator has 5250 running watt capacity. what if one heating element was disabled? would that help?
Your water heater should draw 4500W @ 240V total. If it is possible to disable one of the elements without damaging the heater, that would most likely only result in lukewarm water from a heater that never shuts off.

I still would like to know how you draw 220 out of that L14-20 connector.
You don't. Your generator is providing 240V single-phase power, split into two 120V legs. Halton explained how those can be connected to provide single-phase 240V, 120V leg-to-neutral, or a combination of the two to any given load.

the two hots that leave the 4 prong receptacle could be wired to a 220 appliance and provide the 220 volt? I am a little weak in understanding 220volt anyway.
No. 220V may be the stated current requirement for your well pump. That is a common load design, since it allows the load to operate with power ranging from 198V to 242V (90% to 110% of the design value). The utility supply to your house and the supply from your generator are both 120/240V supplies, and the well pump should work equally well with either - provided, of course, that the generator can provide the amperage the well pump needs.

In addition to the owner's manual for your generator and the thread that PJmax suggested - Congratulations! You have a Generator - reading a copy of Wiring Simplified might help answer a lot of your questions.
 
  #15  
Old 01-04-13, 11:30 AM
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Nashkat1, thanks for your input.

FYI, I did read the generator sticky, good info. I have done a lot of do it yourself wiring over the years. With 120 volt.

240 is confusing to me. as stated. I know the power supplied to my house comes in on Bus Bar 1 and Bus Bar 2. Both 120 Volt. and some property of each of these power lines makes them different, and when one power line from Bus bar 1 and one power line from bus bar 2 are connected to say the electric dryer, they produce 240 volt.

Is this difference the "phase" of the current to each bus bar?

Then, if this is true, how does my single phase generator produce 240?

I understand that if this type of theory info. is beyond what the forum is for, I can do some more book research.
 
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Old 01-04-13, 11:52 AM
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Then, if this is true, how does my single phase generator produce 240?
The generator has two windings. Each one produces 120v. Both hots are wired to the 4 prong outlet to get the 240.

To get 120v they take one hot from one winding to the duplex 120v outlet on your gen, and one hot from the other winding to the other duplex connector.

Hope this helps.


 
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Old 01-04-13, 06:04 PM
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Is this difference the "phase" of the current to each bus bar?

Then, if this is true, how does my single phase generator produce 240?
It is commonly referred to as different phases and, IMO, it is. Unfortunately, as you note, that gets confusing when referring to both together as single-phase. For that reason, we commonly refer to the power supplies to each hot bus as a leg. It is also called a split-phase (or just as a phase). Perhaps thinking of it as a split of the single phase 240 will help.

Each leg, or split, can be combined with a neutral to give 120V power, or the two splits can be used together to provide 240.

The neutral, BTW, is tapped from the center of the generator coil.
 
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Old 01-05-13, 09:02 PM
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thanks for all the good info. things make a lot more sense to me now!
 
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