Just installed 220V receptacle, trips breaker

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  #1  
Old 09-05-04, 05:09 PM
fusion_ta66
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Just installed 220V receptacle, trips breaker

Hello everyone, new poster here.
Here's the background info. I just ran a new circuit for a 220V/50amp receptacle in my detached garage. It is a 3-prong receptacle, so I am using 6-2 romex. I have a square D breaker box in my garage, that uses HOM type breakers, so I picked up a dual-pole 50 amp breaker for it. The garage box is fed from the house box off of a 50amp breaker. I wired the breaker as follows: black wire to one pole of the breaker, white to the other pole, copper wire to the ground bar. Everytime I flip the breaker on, the 50amp breaker that feeds the garage trips. I have nothing plugged into the receptacle. Since I am not drawing any current off of the breaker I just installed, it baffles me as to why it trips the breaker inside the house everytime. Any insight?

thanks
Joe
 
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  #2  
Old 09-05-04, 05:14 PM
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If you're using 50-amps on one circuit from the 50-amp subpanel, that doesn't leave much for the other circuits. Are you going to weld in the dark?

The wiring in the subpanel sounds correct, so I can only conclude that the short is in the cable or at the receptacle.
 
  #3  
Old 09-05-04, 05:20 PM
sjr
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Need a few more details...

Is the breaker feeding the garage a GFCI? Is the grounding bar bonded to the neutral bar in the garage subpanel? What type/size wire did you use as a feeder to the subpanel?

Describe how you made the connection to the 50amp receptacle (which wires went where). What is the receptacle for?
 
  #4  
Old 09-05-04, 06:00 PM
fusion_ta66
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Thank you both for the prompt replies. To answer your questions:

The grounding bar is bonded to the neutral bar. As far as size/type of wire fed to the garage, that was done before I moved in, but judging by the size of the wire fed into the box, I'd say it's 6 gauge. As far as the receptacle, I wired the black into the smaller slot, the white into the larger slot, and the ground into the hole. I am not very experienced with electric (as you probably noticed). The breaker feeding the garage just looks like a normal breaker to me, I'm not sure how to tell if it's GFCI or not.

The receptacle is for a welder, but I have not plugged anything into it yet, it just keeps tripping the house breaker everytime I flip the 220v breaker to 'on'. The reason I used a 50amp breaker was because I really didn't know that the house breaker for the garage was only 50amps, the main disconnect breaker on the garage box says 100 on it. Either way, would there be any reason for the breaker to trip without any current load on it?

If I replaced the 50amp breaker I just installed on the new circuit with a 40amp, would that do anything at all? The welder is 50amp max draw, I probably won't ever need to draw 50amps.


thank you
Joe
 
  #5  
Old 09-05-04, 06:10 PM
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Does the house breaker trip if you leave the welder breaker in the garage off?
 
  #6  
Old 09-05-04, 06:46 PM
fusion_ta66
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No, only when I flip the welder breaker in the garage.
 
  #7  
Old 09-05-04, 06:53 PM
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Please describe the welder receptacle further. There should not be a "larger slot" and "smaller slot". Perhaps you have the wrong receptacle, or you connected it wrong. Remove the receptacle and leave the wires hanging (and separated of course). Then try that breaker again.
 
  #8  
Old 09-05-04, 07:43 PM
fusion_ta66
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John,
The receptacle looks just like a standard 110v 3-prong receptacle. Two 'slots', where the blades of the plug enter, and one 'hole', where the ground prong goes in. The difference is that this receptacle is much larger and deeper than a 110v; it is a surface mount 220V/50amp receptacle. When looking at it straight on, with the ground 'hole' towards the bottom, the right hand side slot is larger than the left slot.
 
  #9  
Old 09-05-04, 08:31 PM
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Can you tell from the below link what receptacle you have?....Roger

http://www.leviton.com/sections/techsupp/nema.htm

Is it a 6-50R?
 
  #10  
Old 09-05-04, 08:50 PM
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Okay, sounds like a 6-50R.

Let us know the results of the "remove the receptacle" experiment I suggested.
 
  #11  
Old 09-05-04, 10:20 PM
fusion_ta66
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John,
I did the experiment, the breaker did not trip this time. I then switched the black and the white wires on the receptacle, and it did not trip the breaker. I am puzzled, I thought the black and white wires were interchangable on the receptacle and the breaker, is this true? I was hesitant to plug in my welder, since I don't know if it is going to work properly or not. Am I worrying too much, should I try and plug it in?
 
  #12  
Old 09-06-04, 05:43 AM
sjr
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The phase wires should be interchangeable on a 240-volt receptacle. I would try reconnecting them the way you did originally--it is possible that there was a short that occured when you initially placed the receptacle back in the box.
 
  #13  
Old 09-06-04, 08:14 AM
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As SJR says, the issue isn't design, it's workmanship. You did everything correctly, but sloppy. You created an accidental short when repacking the box. Switching the wires just allowed you to try again.
 
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