a friend of mine recently bought a house.the home inspecter showed him that some of the lights would come on when the range was turned on and also the panel would get hot every now and then. apparintly he saw nothing wrong and passed the house anyway. i got there and found that one of the phase legs on the main braker was almost to hot to touch. the wire was not making a good connection on the breaker. i replaced the breaker and everthing was fine. i would like to know if power was going to the range on the good phase and when the range was turned on that power would travel through the range back on the affected phase powering the affected phase in the panel. i would like to know how exactly this would work if that is the case. and if the affected phase leg on the breaker somehow made a connection while this was happening would the main trip?
range powering affected phase leg?
- Thread starter gwg
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- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: range powering affected phase leg?
I'm afraid that I do not understand what you are trying to describe. Questions:
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I'm afraid that I do not understand what you are trying to describe. Questions:
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- <font size="2" face="Verdana, Helvetica, sans-serif">What was hot to the touch? The main breaker itself? Incoming wire from the meter to the main breaker?</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">What breaker did you replace? The main breaker? The branch circuit breaker for the range?</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">What do you mean by saying lights would come on when you turn on the range? What lights? Are you saying, for example, that when you turn the oven on to 350 degrees, or perhaps when you turn the front right burner on to "low," the lights in the pantry came on? This could not have been fixed by replacing a main breaker.</font>
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: range powering affected phase leg?
You do have a strange situation. I think you are interpreting it correctly. But just to make sure I understand it, I infer that the kitchen light switch could be turned on and off all day, but the lights would not work. But if you were to leave the switch on, and then turn on the burner, the lights came on. In other words, the burner switch did not function in place of the normal light switch, but rather as a second switch in series with the normal light switch.
An overhead kitchen light might draw 200 watts. Let's call it 240 watts. In a 120 volt system, that equates to 2 amps. From that, we calculate a resistance of 60 ohms. If you add that resistance to the resistance of the bad connection at the main breaker, the total resistance was too much to allow any significant current to flow, so the lights did not burn brightly.
On the other hand, the resistance of the oven would be much smaller. That would cause much more current to flow through the bad connection at the main breaker. I suspect that this caused the connection to become a better (lower resistance) connection. This in turn allowed enough current to flow in the lights for you to see them shining.
That's just a guess, of course.
You do have a strange situation. I think you are interpreting it correctly. But just to make sure I understand it, I infer that the kitchen light switch could be turned on and off all day, but the lights would not work. But if you were to leave the switch on, and then turn on the burner, the lights came on. In other words, the burner switch did not function in place of the normal light switch, but rather as a second switch in series with the normal light switch.
An overhead kitchen light might draw 200 watts. Let's call it 240 watts. In a 120 volt system, that equates to 2 amps. From that, we calculate a resistance of 60 ohms. If you add that resistance to the resistance of the bad connection at the main breaker, the total resistance was too much to allow any significant current to flow, so the lights did not burn brightly.
On the other hand, the resistance of the oven would be much smaller. That would cause much more current to flow through the bad connection at the main breaker. I suspect that this caused the connection to become a better (lower resistance) connection. This in turn allowed enough current to flow in the lights for you to see them shining.
That's just a guess, of course.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: range powering affected phase leg?
I don't think we are seeing the same picture in our respective minds. Try drawing a picture as follows:
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Now let's talk about the bad connection. Turn off the range, and make sure the light switch is on. Just as in the "normal circumstances," current will flow from "B" to the light and back to "N." However, with the bad connection, the resistance will be high, and the current will be low. There will be current through the light bulb, but it will not be enough current to cause the lamp to glow brightly enough for the human eye to notice.
Now turn on the range. There will be both the current paths described above. The current paths do not change. There will be current flowing from "A" to the range and back to "B." There will be current flowing from "B" to the light and back to neutral. The difference is that the current from the range will overcome the resistance of the bad connection. That will permit more current to flow through the "not so bad anymore" connection through the light, and you will be able to see the lamp glowing normally.
I don't think we are seeing the same picture in our respective minds. Try drawing a picture as follows:
</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Draw 3 vertical lines, representing wires coming from the meter. Label them A, B, N.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Draw a symbol for the main breaker on "A" and "B." Continue the lines downward to represent the two bus bars. Terminate the line for "N" on a box to represent the neutral bar.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Let's say "A" was the "good phase," and "B" was the phase with the bad connection at the main breaker.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Draw a symbol for a 2-pole breaker to take power from both A and B, and draw horizontal lines over to a box to represent the range.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Draw a symbol for a 1-pole breaker to take power from B. Draw a horizontal line over to a circle to represent a light. From the other side of the circle, draw a horizontal line back to the neutral bus.</font>
Now let's talk about the bad connection. Turn off the range, and make sure the light switch is on. Just as in the "normal circumstances," current will flow from "B" to the light and back to "N." However, with the bad connection, the resistance will be high, and the current will be low. There will be current through the light bulb, but it will not be enough current to cause the lamp to glow brightly enough for the human eye to notice.
Now turn on the range. There will be both the current paths described above. The current paths do not change. There will be current flowing from "A" to the range and back to "B." There will be current flowing from "B" to the light and back to neutral. The difference is that the current from the range will overcome the resistance of the bad connection. That will permit more current to flow through the "not so bad anymore" connection through the light, and you will be able to see the lamp glowing normally.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: range powering affected phase leg?
If the lights are wired in series with the range, you would still have that problem. Perhaps I misunderstood the original description, but I infer that replacing the main breaker was the only repair performed, and it resolved all problems. Clearly, replacement of the main breaker would not have solved the problem of lights being wired in series with the range.
I think my own "theory" is probably all wet. But I don't think I can accept this theory either.
If the lights are wired in series with the range, you would still have that problem. Perhaps I misunderstood the original description, but I infer that replacing the main breaker was the only repair performed, and it resolved all problems. Clearly, replacement of the main breaker would not have solved the problem of lights being wired in series with the range.
Re: range powering affected phase leg?
I didnt say wired in series with... I said working in series with, and I will venture a guess that the range was not getting terribly hot.
Lets say B phase is the bad leg.
Current was flowing in on A phase, going through the range back to B phase and the buss bar at reduced voltage. Then out to certan loads, and back to the neutral.
I have seen this before. This could distroy some equipment, but the low impeadace of the range allowed the lights to apperar to be working correctly.
I didnt say wired in series with... I said working in series with, and I will venture a guess that the range was not getting terribly hot.
Lets say B phase is the bad leg.
Current was flowing in on A phase, going through the range back to B phase and the buss bar at reduced voltage. Then out to certan loads, and back to the neutral.
I have seen this before. This could distroy some equipment, but the low impeadace of the range allowed the lights to apperar to be working correctly.
Re: range powering affected phase leg?
This is similar to an energized open neutral. One hot leg feeds the range or any other 240V load which then energizes the other leg. It is indeed a series configuration. The lights would burn at near normal brightness, but any 240V load would not receive adequate power. This scenario would might also occur with a main breaker without a common trip.
I am amazed that the HI let it pass!
This is similar to an energized open neutral. One hot leg feeds the range or any other 240V load which then energizes the other leg. It is indeed a series configuration. The lights would burn at near normal brightness, but any 240V load would not receive adequate power. This scenario would might also occur with a main breaker without a common trip.
I am amazed that the HI let it pass!
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