Generator wiring question

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Old 08-03-12, 05:38 AM
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Generator wiring question

I just purchased a (8000/10000watt) generator. It has an outlet for a 120/240volt 30amp plug. It also has a switch for going to 240v from 120v.
I installed an inlet box and wired to a double 30amp breaker in my main panel.
(note: I'm using an interlock kit). Everything runs fine until I flip the switch on the generator to 240v. That trips the breaker on the generator. Am I correct in assuming I can only feed my main panel 120v? If so, what is the reason for having to use a two pole 30amp breaker from the inlet box? My third question which lead me to all this, I cannot get my well pump to work even though the metered output of that breaker is 240v?
thanks for your help.
a frustrated retiredtim
 
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Old 08-03-12, 07:58 AM
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Hi!

Your question leaves so many variables I dont know where to start. Possible you could explain what specific equiptment you used and how you wired it.

Some questions that the electricians will like to know.

Make and model of gen?
Does the gen have GFI protection/bonded un-bonded?
Did you install a transfer switch or feeding the main panel with breakers?
Do you have a interlock if feeding the main panel?


Pics of what you have done will help greatly if you want the best advice here.
 
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Old 08-03-12, 09:32 AM
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Lawrosa,
Thank you for your reply.
1. generator is a Powerland 8000/10000
2. there are no GFI's from gen thru inlet box to 30amp breaker
3. wired to breaker in main panel
4. I have installed an interlock kit
can't seem to attach picture-do you have an email address I can sent it to or do you have any idea of how to attach it.
thanks, tim
 
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Old 08-03-12, 09:37 AM
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What all are you trying to power up when the breaker trips?

I would not use the generator hooked up to your panel in the 120V only mode unless you have planned and designed your setup for that.
 
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Old 08-03-12, 09:41 AM
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Old 08-03-12, 10:02 AM
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There a switch on the generator thats lets you convert to 240v. When the generator is running with extension plugged in the 120/240 30amp outlet, it run fine and the meter indicates its producing 240v. The minute I flip the 30amp breaker on the main panel it will trip the breaker on the generator. If I disconnect one of the hot wires (red or blk) coming out of the inlet box or run the generator on 125v in works fine and runs everything thats on 120v in the house. Still having trouble attaching picture of breaker panel.
 
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Old 08-03-12, 10:17 AM
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picture of breaker panel

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Breaker panel - 30amp double breaker in positions #2 & #4 are for the generator.
 
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Old 08-03-12, 10:27 AM
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generator panel

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generator panel showing 120/240 switch
 
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Old 08-03-12, 10:43 AM
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The electricians should chime in soon, but answer this.

You are using the 120/240 30amp 4 prong outlet right? ( This is what you need to use,)

You have the switch on 240 right?
 
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Old 08-03-12, 10:51 AM
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You may just be overloading the generator.

1. Turn off ALL breakers before throwing the generator breakers on.
2. Turn on the 240V loads one at a time, but dont try to pull more than 30amps at once.
3. You can experiment with different load combinations, but I would not load it up so that the voltage goes below 220volts and you should be fine.
 
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Old 08-03-12, 10:59 AM
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The minute I flip the 30amp breaker on the main panel it will trip the breaker on the generator.
Sounds like you're overloading it. As Auger01 asked,
What all are you trying to power up when the breaker trips?
To ask it a different way, what are you turning off before switching to generator power?

A 30A supply is not enough to feed most residential systems, which are typically either 100A or 200A services. If you would like to supply a large portion of your total load with the generator, is there a reason you decided to use the 30A receptacle rather than the 50A one?
 
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Old 08-03-12, 11:05 AM
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I have attempted this 3 ways:
1. starting gen, all breakers off, with gen in 240v mode, flipping only the breaker to the generator (30amp 2 pole-slots 2 &4). the breaker on generator trips immediately (like the panel won't accept 240v coming in)
2. If I leave the voltage switch at 125v, everything except my well and electric range works.
3. I have disconnected black and red wire at breaker, generator doesn't trip and each leg registers 120v.
 
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Old 08-03-12, 11:16 AM
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I've gone with the 30amp for 2 reasons - 1. I had the extension cord.
2. there is nothing over 30amps I need to run
(well pump is 240v requiring about 10amp-it is currently on a 2 pole 15amp breaker that has been running fine with normal electricity from pole)
 
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Old 08-03-12, 11:25 AM
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I think I see the problem, if the generator breaker is the top right it appears that it is a mini breaker that is both handles from the same pole thus creating a dead short when both are connected but no short when one or the other is only connected, the reason i think this is because you have a normal 2-pole breaker in the bottom of the panel
 
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Old 08-03-12, 11:27 AM
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Can you tell me how many volts each leg of the panel carries (the leg that the breaker snap into). I understand that a normal breaker snapped into the leg will give you 120v (black)and to get the 240v you attached the other lead (white)to another breaker on same the leg. Doesn't that mean that the leg is actually carrying 120V? If so, how can you back feed 240v into that leg?
 
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Old 08-03-12, 11:32 AM
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Can you explain a little more? It trips with all the breakers except for the generator are off.
 
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Old 08-03-12, 11:37 AM
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Portable generators sold after a certain date are required to have GFCI protection on their outputs. I suspect that you are experiencing a parallel path between the neutral and the equipment grounding conductor and THAT is causing the circuit breaker to trip.

Read carefully the manual and see if it mentions the following:

1. Ground Fault Circuit Interruption.

2. Bonded or unbonded neutral connection.
 
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Old 08-03-12, 11:38 AM
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"If I disconnect one of the hot wires (red or blk) coming out of the inlet box or run the generator on 125v in works fine and runs everything thats on 120v in the house"

each leg or pole of you panel is 120 volts to neutral, 240 volts leg to leg so if that breaker is indeed a mini breaker in which both breakers are connected to the same leg by flipping the breaker you cause a dead short to the generator this can be checked by removing the wires from the breaker, restoring power to the panel, turning on the breaker in question and measure voltage from each leg of the breaker and each leg to ground

you should get 240 leg to leg 120 leg to ground
 
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Old 08-03-12, 11:47 AM
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The breaker I'm using for the generator is a GE THQP230 2 pole 30amp. Is that the right breaker?
 
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Old 08-03-12, 11:55 AM
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Sorry, I think I'm loosing it. Should be leg to ground I'm getting 120 each. Leg to leg is 0.
 
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Old 08-03-12, 11:58 AM
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IIRC GE is one brand of panel that allows a 2 pole breaker to be located on the same leg or 2 different legs by moving the breaker up or down 1/2 space. I too suspect this breaker is feeding into the same hot leg and creating a dead short between the 2 hots.

The solution would be to remove a breaker below the generator breaker and move the breaker down 1/2 space, but then the interlock won't work or install a full size 2 pole 30.
 
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Old 08-03-12, 12:01 PM
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I looked back at your picture, and I'm pretty sure braether3 nailed it. What you've been doing, then, is connecting both legs from the generator to a single leg in the panel. A dead short, every time.

Can you tell me how many volts each leg of the panel carries (the leg that the breaker snap into). I understand that a normal breaker snapped into the leg will give you 120v (black)and to get the 240v you attached the other lead (white)to another breaker on same the leg. Doesn't that mean that the leg is actually carrying 120V? If so, how can you back feed 240v into that leg?
Each of the feeder bus bars in the panel carries one-half of the single-phase 240V service to your house. Each horizontal pair of full size breakers is connected to the same split phase. The split phases feed alternate rows, top to bottom. To get the original single-phase 240V power, then, you connect a pair of conductors to any two vertically adjacent full size breakers. There is one other way to do it, but it doesn't apply well to bringing power in from a generator.

Bottom line, 240V requires connecting to the two separate legs, or phases, at the same time. Not
to another breaker on same the leg.
I've gone with the 30amp for 2 reasons - 1. I had the extension cord.
2. there is nothing over 30amps I need to run
(well pump is 240v requiring about 10amp-it is currently on a 2 pole 15amp breaker that has been running fine with normal electricity from pole)
The question isn't "What is the largest single load you want to back up?" The question is "What is the total load you want to back up?"

Wiring Simplified is an inexpensive resource that explains many of these concepts.
 
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Old 08-03-12, 12:30 PM
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Running 240 volts into a single leg would explain most of his problems, but he said everything worked except the 240 volt loads when he ran 120 into one leg. That doesnt explain how the other 120 volt leg was working.
 
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Old 08-03-12, 12:33 PM
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Does this mean I need a 30amp single pole breaker for slot 4 (red wire) and a second one that fits slot 6(blk wire)? Do the handles get somehow fasten together?
 
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Old 08-03-12, 12:51 PM
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Wait for the electricians to respond but I think this is the breaker you need.

General Electric / GE THQL2130 Circuit Breakers | RELECTRIC


For comparison this is the breaker you currently have

General Electric / GE THQP230 Circuit Breakers | RELECTRIC
 
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Old 08-03-12, 12:56 PM
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That was the problem.
I would like to thank everyone that took the time to help me resolve this problem. It was driving me crazy. Now i can sleep tonite and not go thru all the deals of what i might have done wrong.
I'll like to buy you all a beer so if you're ever in new hampshire look me up.
Thanks again,
tim
 
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Old 08-03-12, 02:03 PM
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I'll like to buy you all a beer so if you're ever in new hampshire look me up.
Thanks again,


Ill be there in a few hours, leaving now....LOL
 
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Old 08-03-12, 02:18 PM
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Congrats to braether3 for seeing the issue.

Heres your beer from the OP.
 
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Old 08-03-12, 03:04 PM
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Does this mean I need a 30amp single pole breaker for slot 4 (red wire) and a second one that fits slot 6(blk wire)? Do the handles get somehow fasten together?
Close -- very close.

You actually need a 2-pole breaker, so that both phases will trip together, not two single-pole breakers with a handle tie. Given that the breaker you had in there is a GE THQP230 2 pole 30amp, the exact breaker you need is almost certainly the GE THQL2130 that lawrosa linked to earlier. Nice digging, Mike!

I would put it positions 2 and 4. Not sure that's necessary, but I would want to keep it as close to the utility feed as possible. Just for shiggles. And yes, black for A phase and red for B phase is customary for 120/240V services, but the electricity doesn't really care what color the insulation is. The requirement is that be different and use acceptable colors. That said, I would still wire it 2 black and 4 red.

Thanks again to braether3 for the spot that got us all on track!

Auger01 has had some sage advice on how to proceed, which I'm sure you'll want to follow as you bring every thing on line. Auger01:

And above all, thank you for listening, Tim! Here's one for you until I can get to NH:
 
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Old 08-03-12, 05:05 PM
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Today, 01:30 PM
Auger01
Running 240 volts into a single leg would explain most of his problems, but he said everything worked except the 240 volt loads when he ran 120 into one leg. That doesnt explain how the other 120 volt leg was working.





Read more: http://www.doityourself.com/forum/ne...#ixzz22WkQ4tO2


My best guess is it was backfeeding thru 240 volt loads
 
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Old 08-03-12, 05:08 PM
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Thanks guys glad you got it resolved !
 
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Old 08-03-12, 07:39 PM
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WOW, thats a weird one. I used to backfeed my house with 10/3, to a 30A Double pole, and shut the mains off FIRST. Real easy to do, but not the best, and need to get the interlock kit. I use a DTTS now. Almost sounds like 1 leg was taking 240v and would trip. The 10/3 wiring is needed, red and black to the breaker at the mains, and white and ground to neutral bus bar, etc. This will give you approx 60 amps, 30 each side. Also, was any of the legs grounding out? Bad connection, etc?

Mod Note: Never back feed a panel without a transfer switch or interlock. What the poster did could kill someone.
 

Last edited by ray2047; 08-03-12 at 08:28 PM.
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Old 08-03-12, 09:33 PM
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It will not give you 60 amps cumulatively it's still 30 amps whether it's 120 or 240
 
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Old 08-04-12, 10:52 PM
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crap that right, it will be 30A total, but you would think it would...lol ...So, when any pole gets to 30A, it will shut off both ?
 
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