Not getting 240 volts on double pole breaker

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Old 11-26-18, 09:25 AM
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Not getting 240 volts on double pole breaker

Trying to wrap up my project. Latest issue is testing voltage of new breakers in subpanel. I am getting 120 volts from each pole to ground but am not getting 240 when measuring across poles. I'm not getting any reading at all across poles. I have three double pole breakers in there and it is the same with all three. What could the wiring problem be? I have a GE subpanel and pulled the breakers to make sure they are in contact with both legs. Appears they are.
 
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Old 11-26-18, 09:34 AM
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The only way that is possible is if you are measuring between the same "phase" and are therefore reading a potential difference of zero (120 minus 120). I'm not sure it's even possible to install a breaker in such a way, even if it's the incorrect kind for your particular panel. Someone else will chime in shortly.
 
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Old 11-26-18, 09:56 AM
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In GE panels it is possible to install a 2-pole breaker such that is only contacting one phase. Since the problem affects the whole panel, that points to the upstream feeder. The breaker feeding this panel needs to be relocated up or down half a step.
 
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Old 11-26-18, 10:01 AM
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Ok, I will pull the 50 amp that feeds the panel and see if it is contacting both phases.
 
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Old 11-26-18, 10:01 AM
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You need to measure 240vAC across the breaker. The only time you can check from either leg to ground is if there are NO wires connected to the breaker.
 
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Old 11-26-18, 12:17 PM
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I checked each leg with no wires connected to breaker---120 volts. I checked across the breaker for 240 with wires connected to breaker and reading was 0. I checked the breaker that was feeding the panel, a 50amp double pole and had the same reading. I removed the 50 amp to make sure it was connected to both legs and it was. I assume the problem originates at the supply breaker since I am getting the same readings. There was a sticker on the 50 amp breaker that said, "not rated for series rated combination." Just throwing that in just in case it means something that might affect my setup.
 
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Old 11-26-18, 12:37 PM
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I failed to notice this is a subpanel. Are you sure you even have two feeds at the subpanel to achieve 240V? You can't simply take 120 and 120 to get 240. They need to be 180 degrees out of phase.
 
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Old 11-26-18, 12:58 PM
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Ok, here's a photo (hopefully) of where the 50 amp supply is connected. Does there appear to be any problem in making the connection to both lugs?
 

Last edited by mickeyrory; 11-26-18 at 12:59 PM. Reason: wrong photo
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Old 11-26-18, 01:00 PM
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No problem at that end.................
 
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Old 11-26-18, 01:01 PM
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Here's the correct photo of where the 50 amp is connected

Name:  DSC06692.jpg
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Last edited by PJmax; 11-26-18 at 01:37 PM. Reason: labeled pic
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Old 11-26-18, 01:26 PM
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I had checked the breakers in the subpanel with wires not attached. However, I hadn't done that with the 50 amp supply. I just checked and one of the two sides of the breaker was 120 volts and the other 0. Would that be an indication that I have a bad breaker?
 
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Old 11-26-18, 01:31 PM
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THQP250 slim breaker? needs to move down 1/2 space.
 

Last edited by Astuff; 11-26-18 at 02:13 PM. Reason: Slim breaker, not slime.
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Old 11-26-18, 01:38 PM
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The breaker needs to connect to the A bus and well as the B bus.
You should have 240vAC from A to B. Measure carefully - don't create a short.
 
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Old 11-26-18, 02:47 PM
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My 50 amp is the size of two full sized breakers. It is connecting on both A and B. I want to make sure I understand the measuring carefully. Put one lead on one screw of the breaker and the other lead on the other screw? Or, should I test without the breaker being in by touching A and B?
 

Last edited by mickeyrory; 11-26-18 at 02:50 PM. Reason: need to add information
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Old 11-26-18, 02:48 PM
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Do you get 240vAC between the A and B bus ?
 
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Old 11-26-18, 03:20 PM
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If you measure 240 directly across the bus bars, but not across the breaker, then either the breaker isnt seated properly or it is faulty.
 
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Old 11-26-18, 03:25 PM
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Replaced the breaker! Everything is working fine; all measurements good; heaters are working.
Thanks to everyone who helped out. THANKS to HOME DEPOT for selling me a bad breaker and making me think I screwed up the job.
 
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Old 11-26-18, 03:49 PM
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Glad it was something simple!
 
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Old 11-28-18, 11:38 AM
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You originally said you had three double pole breakers all with the same issue. Did you find all of them to be defective?
 
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Old 11-30-18, 10:34 AM
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I have three double pole breakers in there and it is the same with all three.

Good point lakeseed. ...........
 
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Old 11-30-18, 11:53 AM
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I have a feeling that they may have just needed to be reset (turned off then back on), but giving the OP the benefit of the doubt. Hopefully we'll hear back.
 
 

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