What will cause my main breaker to trip?
It’s totally random, sometimes the dryer running will throw the breaker. Sometimes it will be a hot shower, sometimes it’s washing our hands in the sink. It’s unpredictable what will throw the breaker. I replaced the main breaker about 3 years ago but we still encounter this problem, especially around winter time.
Running all of the air conditioners all summer alongside all of the appliances is never a problem. As soon as we boot up the furnace in the fall all hell breaks loose. We have shut off each individual breaker to every large appliance including the furnace (we haven’t turned it back on since the first time this happened again this fall) one at a time and something still trips the main. I’m at a loss here.
Question from user Liberty at stackexchange
Answer:
I'd venture that you have a loose connection somewhere. As it heats up, the wire expands and contacts another thing that it shouldn't causing the breaker to trip. To be fair, tripping the main is unusual, as opposed to just the circuit that the loose wire is on.
Because it's the main tripping, you will probably want to start at the breaker panel itself.
Remove the panel cover and look at the label inside - it should have torque specs for the main lugs and the individual breakers.
Set your torque wrench/screwdriver to the recommended setting.
Turn off the main breaker.
Torque each and every screw (breakers, neutral & ground screws on the busses, main lugs (use extreme caution here as there is still power on these) you can find.
NOTE: I'd strongly suggest buying the proper screwdriver to fit the screws in your panel. It will make a world of difference in how easy it is to get the screws properly tightened. A slotted screwdriver will work, but will be very difficult to get it as tight as it should be. A Phillips will work, but will likely damage the screw heads before they're properly tight. My breakers (Siemens) use a #2 square drive, yours may be different.
If that doesn't seem to fix the problem after a few days, you'll have to move on to checking each individual circuit.
Since running the furnace seems to cause it more frequently, that's where I'd start. The furnace burns oil for heat, but needs electricity to run the blower to move the heat through the house.
Turn off the breaker for the furnace.
Open every switch/receptacle box on that circuit and tug on every wire.
Every one that has the slightest apparent movement at the screw holding it down deserves another turn or two of the screw to ensure it's good and snug.
Each switch, receptacle, etc. will have torque specs associated with it. You'll probably need to go to the manufacturer's web site to find out what those settings are, but it's worth the extra bit of time. Write down the settings as you go - odds are good that most devices in your house are one of two or three major brands/models so you'll compile your own little reference list.
If this doesn't fix it, move on to the next circuit, working your way through the entire panel, starting with the circuits whose appliances seem to be the most frequent culprits.
If you find that there are several loose screws on each circuit, I'd make a plan to take a couple of Saturdays and work your way through each breaker on the panel double checking them all. After all, if some weren't tight enough, odds are good many more won't be tight enough. As an added bonus, it will allow you to make a good map of exactly which devices in the house are on which breaker which will be handy for the future. While there's space for labeling them in the panel, there's not much space and they can be cryptic, missing info, or downright misleading at worst.
Answer from user FreeMan at stackexchange
It’s totally random, sometimes the dryer running will throw the breaker. Sometimes it will be a hot shower, sometimes it’s washing our hands in the sink. It’s unpredictable what will throw the breaker. I replaced the main breaker about 3 years ago but we still encounter this problem, especially around winter time.
Running all of the air conditioners all summer alongside all of the appliances is never a problem. As soon as we boot up the furnace in the fall all hell breaks loose. We have shut off each individual breaker to every large appliance including the furnace (we haven’t turned it back on since the first time this happened again this fall) one at a time and something still trips the main. I’m at a loss here.
Question from user Liberty at stackexchange
Answer:
I'd venture that you have a loose connection somewhere. As it heats up, the wire expands and contacts another thing that it shouldn't causing the breaker to trip. To be fair, tripping the main is unusual, as opposed to just the circuit that the loose wire is on.
Because it's the main tripping, you will probably want to start at the breaker panel itself.
Remove the panel cover and look at the label inside - it should have torque specs for the main lugs and the individual breakers.
Set your torque wrench/screwdriver to the recommended setting.
Turn off the main breaker.
Torque each and every screw (breakers, neutral & ground screws on the busses, main lugs (use extreme caution here as there is still power on these) you can find.
NOTE: I'd strongly suggest buying the proper screwdriver to fit the screws in your panel. It will make a world of difference in how easy it is to get the screws properly tightened. A slotted screwdriver will work, but will be very difficult to get it as tight as it should be. A Phillips will work, but will likely damage the screw heads before they're properly tight. My breakers (Siemens) use a #2 square drive, yours may be different.
If that doesn't seem to fix the problem after a few days, you'll have to move on to checking each individual circuit.
Since running the furnace seems to cause it more frequently, that's where I'd start. The furnace burns oil for heat, but needs electricity to run the blower to move the heat through the house.
Turn off the breaker for the furnace.
Open every switch/receptacle box on that circuit and tug on every wire.
Every one that has the slightest apparent movement at the screw holding it down deserves another turn or two of the screw to ensure it's good and snug.
Each switch, receptacle, etc. will have torque specs associated with it. You'll probably need to go to the manufacturer's web site to find out what those settings are, but it's worth the extra bit of time. Write down the settings as you go - odds are good that most devices in your house are one of two or three major brands/models so you'll compile your own little reference list.
If this doesn't fix it, move on to the next circuit, working your way through the entire panel, starting with the circuits whose appliances seem to be the most frequent culprits.
If you find that there are several loose screws on each circuit, I'd make a plan to take a couple of Saturdays and work your way through each breaker on the panel double checking them all. After all, if some weren't tight enough, odds are good many more won't be tight enough. As an added bonus, it will allow you to make a good map of exactly which devices in the house are on which breaker which will be handy for the future. While there's space for labeling them in the panel, there's not much space and they can be cryptic, missing info, or downright misleading at worst.
Answer from user FreeMan at stackexchange