A coworker of mine asked me a question today about his home. Seems when he turned off his heater at the thermostat, some lights went off in the house. He checked the circuit breaker panel and found that all of the breakers on one of the legs of his 240 volt panel were tripped. Also, the breaker for the heater blower motor was on the other leg and did not trip. Could this be a coincidence that the breakers tripped at the same time he turned off the heater, and an existing problem happened to surface at that time? If it's not a coincidence, what could have caused something like that to happen by turning off the heater? It's a forced air gas heater with a 120v blower motor.
Half the breakers in panel tripped
- Thread starter mattalfa
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bonding jumper
Senior Member
Re: Half the breakers in panel tripped
Is the heater old? This is a very interesting one, first I would think that maybe the motor kicking off caused a surge on the panel and possibly cause the breakers on the one leg to trip. But this does not seem feasable to me because circuit breakers are not instantanious trip, and surges do not last long enough durations to cause a trip. I wonder if there is a grounding/neutral problem. I'm anxious to hear others diagnosis.
[ February 04, 2005, 01:49 PM: Message edited by: bonding jumper ]
Is the heater old? This is a very interesting one, first I would think that maybe the motor kicking off caused a surge on the panel and possibly cause the breakers on the one leg to trip. But this does not seem feasable to me because circuit breakers are not instantanious trip, and surges do not last long enough durations to cause a trip. I wonder if there is a grounding/neutral problem. I'm anxious to hear others diagnosis.
[ February 04, 2005, 01:49 PM: Message edited by: bonding jumper ]
stud696981
Senior Member
Re: Half the breakers in panel tripped
Wow, that's weird. The only thing I can think off at the moment is something on the lines of what the above post said. An open neutral would cause the voltage to rise on one side, thus causing a resistive load to draw more current. Still this seems weird.
Wow, that's weird. The only thing I can think off at the moment is something on the lines of what the above post said. An open neutral would cause the voltage to rise on one side, thus causing a resistive load to draw more current. Still this seems weird.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: Half the breakers in panel tripped
Does the coworker live with someone that enjoys practical jokes?
The nature of these symptoms implies a certain technical expertise.
The coworker says the breakers were "tripped". Is this certain? Were the particular breakers capable of indicating a tripped state, or are tripped and off the same handle position?
Also, considering:
I can't fathom a scenario that would result in this.
Does the coworker live with someone that enjoys practical jokes?
The nature of these symptoms implies a certain technical expertise.
The coworker says the breakers were "tripped". Is this certain? Were the particular breakers capable of indicating a tripped state, or are tripped and off the same handle position?
Also, considering:
Did the tripped breakers include only single poles, or where the double poles also tripped?
I can't fathom a scenario that would result in this.
inspector 102
Senior Member
- Location
- Northern Indiana
Re: Half the breakers in panel tripped
Have you checked the voltage of each buss at the panel board. If there is an unbalanced load, such as might occur with a loose or lost nuetral, could this create a low or high voltage situation that affects the reaction of the overcurrent device. Not beingan electrical engineer, I would start simple and eliminate from there. Keep us informed.
Have you checked the voltage of each buss at the panel board. If there is an unbalanced load, such as might occur with a loose or lost nuetral, could this create a low or high voltage situation that affects the reaction of the overcurrent device. Not beingan electrical engineer, I would start simple and eliminate from there. Keep us informed.
alan mcneil
Member
- Location
- Massachusetts
Re: Half the breakers in panel tripped
I would agree with MSD post, loose connection on bus bar.
I would agree with MSD post, loose connection on bus bar.
Re: Half the breakers in panel tripped
If it were a bus that was getting hot there's a couple of thoughts that should go along with this.
1)It is common for a panel to have (2) vertical rows of breaker mounted horizontally with the loads ends pointing away from the one installed immediately across from it. The breaker on one side and the one mounted immediately opposite share the same bus. The pair mounted immediately above and below share the other bus which results in every other pair of breakers mounted end to end alternating the bus that they are feed from.
As such the theory that the breakers on side of the panel tripping as a result of heating from the bus is questionable because every other breaker is feed from an opposite bus.
2)Breakers tripping because of heating from the line end connection may be questionable also since the thermal sensitive elements are connected to the stationary contacts and the load terminals and not likely to since the heat as they would definitely do if there was heating on the load end connection. Heating at the line end may raise the ambient temperature enough to derate the breaker so that it will not carry its full load an nuisance trip. If line end heating is great enough the spring that holds the moving contact down against the stationary contact can weaken enough to cause contact failure.
But remember that is is?important to determine how a breaker tripped. A breaker that trips thermally can not be reset immediately after it trips as you must give it some time to allow the thermal element to cool down and allow you to latch (reset) and close the breaker.
If the breaker trips magnetically you can latch (reset) and reclose the breaker immediately. However it is now a good practice to reclose a breaker back into a faulted condition.
If it were a bus that was getting hot there's a couple of thoughts that should go along with this.
1)It is common for a panel to have (2) vertical rows of breaker mounted horizontally with the loads ends pointing away from the one installed immediately across from it. The breaker on one side and the one mounted immediately opposite share the same bus. The pair mounted immediately above and below share the other bus which results in every other pair of breakers mounted end to end alternating the bus that they are feed from.
As such the theory that the breakers on side of the panel tripping as a result of heating from the bus is questionable because every other breaker is feed from an opposite bus.
2)Breakers tripping because of heating from the line end connection may be questionable also since the thermal sensitive elements are connected to the stationary contacts and the load terminals and not likely to since the heat as they would definitely do if there was heating on the load end connection. Heating at the line end may raise the ambient temperature enough to derate the breaker so that it will not carry its full load an nuisance trip. If line end heating is great enough the spring that holds the moving contact down against the stationary contact can weaken enough to cause contact failure.
But remember that is is?important to determine how a breaker tripped. A breaker that trips thermally can not be reset immediately after it trips as you must give it some time to allow the thermal element to cool down and allow you to latch (reset) and close the breaker.
If the breaker trips magnetically you can latch (reset) and reclose the breaker immediately. However it is now a good practice to reclose a breaker back into a faulted condition.
Re: Half the breakers in panel tripped
Mattalfa, The problem cannot exist without all those breakers having a common load anomally. As physis asked
likeliness of all breakers on one leg being affected is a mystery. A qualified inside wireman with good interpretation skills may be needed in this case.
rbj, Seattle
Mattalfa, The problem cannot exist without all those breakers having a common load anomally. As physis asked
All those neutrals may be connected to a common point that may have a faulty connection. The
likeliness of all breakers on one leg being affected is a mystery. A qualified inside wireman with good interpretation skills may be needed in this case.
rbj, Seattle
Re: Half the breakers in panel tripped
Is it possible he was confused about which direction the breakers were on or off? A friend once called me and said half his house was out. I said did you check the breakers he said yes he flipped them all several times. When I got there he had one bank on and one bank off. He thought they all switched to the right for on and he had switched everything back and forth so much he didn't know what position they were in to begin with. Yes hard to believe but remember lots of people out there are mechanically challenged and don't care to know.
Is it possible he was confused about which direction the breakers were on or off? A friend once called me and said half his house was out. I said did you check the breakers he said yes he flipped them all several times. When I got there he had one bank on and one bank off. He thought they all switched to the right for on and he had switched everything back and forth so much he didn't know what position they were in to begin with. Yes hard to believe but remember lots of people out there are mechanically challenged and don't care to know.
bonding jumper
Senior Member
Re: Half the breakers in panel tripped
"Open neutral.
Power comes in red, thru the load to white, returns via loads on black. The apparent voltage is at 240, for lack of a neutral. E=I?R, so E/R=I. The current doubles because the voltage doubles and pops the breakers.
As breakers trip, the current looks for new paths, adding load to each and eliminating those that peak-out. Keeps getting more intense. These are loads. Not shorts. So main breaker stays ON.
The clue? Time. These are thermal trips."
Is this similar to your idea big john? Could you please elaborate on your post. Thanks
After searching on the internet I found this on this website http://ths.gardenweb.com/forums/load/wiring/msg0100472314086.html :
"Open neutral.
Power comes in red, thru the load to white, returns via loads on black. The apparent voltage is at 240, for lack of a neutral. E=I?R, so E/R=I. The current doubles because the voltage doubles and pops the breakers.
As breakers trip, the current looks for new paths, adding load to each and eliminating those that peak-out. Keeps getting more intense. These are loads. Not shorts. So main breaker stays ON.
The clue? Time. These are thermal trips."
Is this similar to your idea big john? Could you please elaborate on your post. Thanks
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: Half the breakers in panel tripped
I don't think 240 volt loads enter into this, as explained by mattalfa.
Mattalfa, we need some more information. Maybe you could answer some the the questions raised?
Edit typo - Al
[ February 07, 2005, 01:26 PM: Message edited by: al hildenbrand ]
I don't think 240 volt loads enter into this, as explained by mattalfa.
Mattalfa, we need some more information. Maybe you could answer some the the questions raised?
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- <font size="2" face="Verdana, Helvetica, sans-serif">The FA gas heater was turned off by the thermostat (low voltage thermo?).</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The breakers tripped when the thermostat shut off the heater.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The breakers that trip are not on the service leg with the FA gas heater.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">It's wintertime and the AC is not being turned off. . .the heater is turned off.</font>
Edit typo - Al
[ February 07, 2005, 01:26 PM: Message edited by: al hildenbrand ]
Re: Half the breakers in panel tripped
I agree with you Al.
The description of the failure is somewhat vague, and that 1/2 the breakers tripped, knowing the way a panel is constructed, as my previous post described, to try to diagnose the failure or why the breakers tripped would be like shooting at shadows.
Dave
I agree with you Al.
The description of the failure is somewhat vague, and that 1/2 the breakers tripped, knowing the way a panel is constructed, as my previous post described, to try to diagnose the failure or why the breakers tripped would be like shooting at shadows.
Dave
Re: Half the breakers in panel tripped
Not sure why all the breakers tripped.
But I can guarantee you that they lost a leg and it backfed on the 220 load.
This is the reason the lights would come on when they turned on the A/C unit. The same results would of happened if they would of turned on an electric stove, 220v air compressor, etc.
Now what would happen is the source breaker of the backfeed (breaker supplying the 220) sometimes trip because it also carries the entire load of the bus on which the phase that is out is located.
This is a good reason to always start your troubleshooting at the main panel.
Not sure why all the breakers tripped.
But I can guarantee you that they lost a leg and it backfed on the 220 load.
This is the reason the lights would come on when they turned on the A/C unit. The same results would of happened if they would of turned on an electric stove, 220v air compressor, etc.
Now what would happen is the source breaker of the backfeed (breaker supplying the 220) sometimes trip because it also carries the entire load of the bus on which the phase that is out is located.
This is a good reason to always start your troubleshooting at the main panel.
harley
Member
- Location
- Pennsylvania
Re: Half the breakers in panel tripped
It may be "Shock out" the latching portion of breaker is on the light side. When one breaker trips the vibration causes others to trip. Do a test. With breaker in "on" position Take breaker in hand and tap narrow end against table or other hand towards off position.
If electronics are in breaker could be noise on load, buss noise, radios, CBs.
It may be "Shock out" the latching portion of breaker is on the light side. When one breaker trips the vibration causes others to trip. Do a test. With breaker in "on" position Take breaker in hand and tap narrow end against table or other hand towards off position.
If electronics are in breaker could be noise on load, buss noise, radios, CBs.
Re: Half the breakers in panel tripped
Thanks for all the input and I'm sorry it took so long for me to get back to the forum. After visiting the house where this happened I was informed that a year ago the power company was working in the area and had done something on the lines that blew the main breaker of his house. The power company replaced the main breaker with one they had on their truck which was a used breaker. They never did come back to replace it with a new one. By the time I got to look at the breakers he had replaced all of them that had tripped on the one leg with new ones. I looked in the panel and felt the main breaker which was extremely hot. The bottom of the breaker was like charcoal it had been cooking for so long. The voltage was balanced on each leg but for some reason, probably because it was a used breaker, it began to cook. I am assuming the breakers on the one leg tripped because they too were damaged when the power company blew out the main breaker but they were still working enough to stay energized. I don't know why the heater would cause them to trip like they did. All seems to be fine now that he has replaced half of his breakers and the main breaker. Thanks again for all of your comments and suggestions.
Thanks for all the input and I'm sorry it took so long for me to get back to the forum. After visiting the house where this happened I was informed that a year ago the power company was working in the area and had done something on the lines that blew the main breaker of his house. The power company replaced the main breaker with one they had on their truck which was a used breaker. They never did come back to replace it with a new one. By the time I got to look at the breakers he had replaced all of them that had tripped on the one leg with new ones. I looked in the panel and felt the main breaker which was extremely hot. The bottom of the breaker was like charcoal it had been cooking for so long. The voltage was balanced on each leg but for some reason, probably because it was a used breaker, it began to cook. I am assuming the breakers on the one leg tripped because they too were damaged when the power company blew out the main breaker but they were still working enough to stay energized. I don't know why the heater would cause them to trip like they did. All seems to be fine now that he has replaced half of his breakers and the main breaker. Thanks again for all of your comments and suggestions.
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