Bang! Main Breaker Tripped.

[Vic Smith]

Last night I was in the basement on the PC, and watching TV. Wife was asleep upstairs. Not sure if the central A/C was running, but most the lights in the house were off. I had a new service put in the year after I moved in, to get 240 so I could put in a new furnace and central air.

200 amp service, I was told. The main breaker at the top of the box has a "pair" of breaker switches that move as one. Each says "100" on it. The furnace/A/C breaker is also a pair, each having "30" on it. The rest of the breakers are 15 or 20. Anyway, there was a loud bang, and all power in the house went off. Didn't see a flash or anything, but the breaker box was out of my line of sight. I thought at first it was a transformer that blew up, which has happened before, but the weather was clear. But that didn't seem right because it was too loud in the basement, which doesn't let hardly any sound in from outside. It woke up my wife too. I grabbed a flashlight and went upstairs, and saw right away my neighbors had power. Thought I was screwed, and would have to get the power company and/or an electrician in. Went back downstairs and found the main breaker had tripped. Flipped it back on and the lights went on. Another breaker was tripped - either a 15 or 20 - that runs some basement lights and the pedestal pump for the lift system. Flipped that back on too. It's been about 24 hours, and everything's been normal. A/C running, pump running, lights working. That bang was pretty loud, about like a 1 1/2" firecracker, but not as sharp sounding. Sounded "electrical" of course, but that's easy to say when the lights go out at the same time. Wish I had a recording. Any idea what the hell happened?

[Home Guy]

Racoon? (or some other nocturnal creature?)

[Evan]

Yeah a temporary dead short on the Service Entrance cables due to an animal or part of a plant may have been the culprit...

If it had been something inside the house on a 15 or

20 amp circuit that tripped the main 200 amp breaker you would have observed some sort of fried wiring...

Was there any sort of abnormal weather events going on, sometimes a transient surge from a nearby yet not direct hit lightning strike can cause a similar issue as well...

[Stormin Mormon]

Current overload maybe? Were you cooking, in addition to laundry dryer, in addition to central AC? maybe the breaker did its job?

Christopher A. Young Learn more about Jesus

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200 amp service, I was told. The main breaker at the top of the box has a "pair" of breaker switches that move as one. Each says "100" on it. The furnace/A/C breaker is also a pair, each having "30" on it. The rest of the breakers are 15 or 20. Anyway, there was a loud bang, and all power in the house went off. Didn't see a flash or anything, but the breaker box was out of my line of sight. I thought at first it was a transformer that blew up, which has happened before, but the weather was clear. But that didn't seem right because it was too loud in the basement, which doesn't let hardly any sound in from outside. It woke up my wife too. I grabbed a flashlight and went upstairs, and saw right away my neighbors had power. Thought I was screwed, and would have to get the power company and/or an electrician in. Went back downstairs and found the main breaker had tripped. Flipped it back on and the lights went on. Another breaker was tripped - either a 15 or 20 - that runs some basement lights and the pedestal pump for the lift system. Flipped that back on too. It's been about 24 hours, and everything's been normal. A/C running, pump running, lights working. That bang was pretty loud, about like a 1 1/2" firecracker, but not as sharp sounding. Sounded "electrical" of course, but that's easy to say when the lights go out at the same time. Wish I had a recording. Any idea what the hell happened?

[Mr.E]

Not at all unusual for a main to come out when a branch has a low ohm short. Many branch type breakers have a lag built in to allow motor starts etc. and the high amp flow caused the main to trip before the lag in the branch. I would disconnect the sump pump, carefully inspect the wires and if an arm/rod activated level switch take the cover off and inspect for an arc. Nothing found would suggest inspection of other visible items on the same circuit, again with power off.

[Art Todesco]

Agreed. I was once changing a lamp in a gas stove (so it was only 120 volt branch) and accidentally shorted the 120. It took out the 100 amp main and not the branch! I think the AC compressor had something to with helping the 100 amp main trip. In addition, if you have 100 stamped on the 2 main breakers, it is 100 amp service, not 200 amp ... well, the service may be 200 amps, but you are only set up for 100 amps.

[Tomsic]

The above makes sense to me too. A branch circuit trip with just the right transients and loads can trip the main breaker as well.

The good news is that your breakers are doing their job.

My rule is to endure one nuisance trip as a fluke. If it happens again, more sleuthing is required.

Tomsic

[trader4]

Forgot to add. From this:

"The main breaker at the top of the box has a "pair" of breaker switches that move as one. Each says "100" on it. "

From the above I would say he has a 100 amp service, not 200.

[clare]

Then you have only a 100 amp 220 volt service. A 200 amp service has a double pole 200 amp breaker.

If you had the AC on, an electric drier, and the oven and stove-top all on, you could overload a 100 amp service breaker if the refrigerator and AC started at the same time - - - . Otherwize unlikely. I've lived with 100 amp service for 31 years - Central air, electric drier, electric stove and oven, lathe in the garage - used to have an arc welder too --. Never blown a 100 amp fuse - the only fuses I've EVER blown have been on the garage circuits - when I had the compressor on 110 instead of 220, and the table saw..

[Vic Smith]

Thanks to everybody. Make me feel better having an idea what happened.. I'm brain dead on electricity. I'll go with the above, but at least pull the cover on the pump level switch and check for arcing. I can handle that. I know that circuit is under-amped, because the breaker has been tripped a few times over the years. Don't know exactly, maybe 5-10 times. Both lift pump, sump pump, and a couple lights are on it. I know I tripped it myself at maybe 5 times by plugging in a 3rd pump during bad rain storms. Sometimes the 3rd pump would run awhile before it tripped. Gave up doing that. But it's tripped a few times besides that. I need to get that split by an electrician, but was waiting until I do the entire house, which I need to upgrade the kitchen.. Nothing "really" wrong I know of, just not enough separate circuits. House was built in '59. Maybe that pump circuit breaker needs replacing too, and is lagging too much, so I'll see about doing that. Might be something I can do myself. Funny thing is, just a few hours before this happened, we noticed a spruce in the backyard has grown sideways to where it's just touching the service wires. It's about 16' up, in the open, so I said to my wife I'll have to call the guy who cut a tree down for me and see he can trim it, or has to cut the tree down.. She said maybe we can trim it. I said it's too high. I was talking to my son, then notice her over there with a 5' stepladder. I cracked up. She never even opened it, seeing once she got under the wire that she badly misjudged the height. Anyway, if you guys say the tripped pump breaker seems to tell the tale, that's good enough for me. I'm already called the tree guy and he'll be here soon. But when I described it he said the tree didn't do it.

[dennisgauge]

What are you talking about? You have NO idea what happened. NONE.

[tangerine3]

You should have that entire circuit checked by an electrician. There could be other problems such as a bare wire inside a box. Otherwise that pump may have been locked up, or have a short in it.

Nothing BEFORE the main breaker, such as a tree touching the wires outside, is going to trip the breaker. Yes, that tree should be trimmed, but a breaker wont trip due to something BEFORE it. The circuit where the small breaker tripped has a problem. I'd get that checked without delay.

[trader4]

Especially when it's the circuit the sump pump is on that's the prime suspect and it's already tripped that breaker 5-10 times over the years. I don't know how critical the sump pump is, but even with what he knows for sure, waiting to fix that until he upgrades the whole house doesn't sound like a good idea to me.

[Vic Smith]

Everything in the house goes through that lift system pump, plus ground water if that gets high. It has a wall switch too and I usually try to keep it off, and turn it on to drain everything every couple days. The stack and the tiles under the basement floor hold a lot. And it's still all tied to a catch basin. Any time it rains the ground water has it running too much, and it will keep going on and off until the ground dries up, sometimes for days. It's set as deep as my sump, but seems to take in more ground water than the sump. But if it's really heavy rain I let it run, because it pumps better than the sump pump, and directly into the sewer instead of re-soaking the ground. Then I forget to turn the wall switch off. I'm doing it manually now. It for sure never tripped when I did the switching. I don't have a good handle on how many times it tripped when I wasn't overloading it by running 3 pumps. I'm going to replace that breaker, and get the circuit checked even if I don't get it split now. The pump is about 4 years old. Cost me $2100 for that job. About $900 for the motor/pump. Previous was close to 50 years old.

know the wall switch is wired wrong. I told the plumber I don't trust switches to be wired right and I'll go flip the breaker. He said, nah, it's ok. Then he got zapped, and said why don't you go get that breaker.

[HeyBub]

Correct: "200 Amp Service" implies 200 amps on each leg of a 220v connection (for a total permissible draw of 400 amps, but nobody calls it 400-amp service).

[clare]

200 amps on 220 volts.

[bob haller]

The OP should at least call the power company and ask for help, and notify them of the offending tree branch......

The OP should also consider the hazards of another main trip if they arent home......

main trips with heavvy rain and the lift pump has no power.

if the home can flood sme $ spent on a electrician is likely a good investment..........

[gregz]

I pushed a button to turn on a motor, and the whole place went dark. Quite an experience. Well, the motor drove the hydraulics to turn one axis on a

65 foot dish antenna. I think it was 50 hp. It literally blew the breaker off the wall, then tripped a main breaker 3-4 miles away. That breaker was in the thousands of amps. I don't recall how many phase. Me and the manager drove over there and triggered the breaker back on. I lost my flashlight in the process. A couple dozen people got back to work, less the big antenna. That was the Apollo station at Goldstone. Just tracking satellites at the time, or the moon.

Greg

[John Gilmer]

Did you upgrade your service panel or did you just only get the power company to upgrade the "service."

If you have 200 amp "service" you CAN have a 200 amp main breaker. If you don't have a 200 amp breaker you should get one.

It's possible that you might be able to upgrade your existing panel but it's also possible that the basic panel isn't rated for 200 amps.

"It depends!"

Some years ago, after calling the power company I found that we had 200 amp "service" to our property. Knowing that, we could safely replace the old fuse box with an up to date 200 amp CB panel.

If you don't have a 200 amp panel the only thing that 200 amp service buys you it slightly less voltage drop in the service drop. But at 100 amps draw, you wouldn't notice the difference.

[Vic Smith]

On Thu, 31 May 2012 16:36:32 -0400, John Gilmer wrote:

Here's all I know. Bought the house in '97. Hot summer. In '98 I decided to get rid of the 2 big window A/C units and put in central air. They were old, one didn't work, and the other hardly worked.. The HVAC guy told me I needed a new service to get 220V. I called in an electrician I found in the local newspaper for an estimate. He pulled up in a Mercedes, and I got on him right away, said. "WTF?! You're the first guy I call for an estimate, and you pull up a shiny effing Mercedes behind my '90 Chevy Corsica? Don't seem a smart way to come out for an estimate." He explained it was an old one, and he got it from his MIL cheap. Anyway, he was a hustler, young, strong, smart, and I liked him. He wanted 11 or 12 hundred, can't remember. I knew that was in the ballpark. Much closer to the pitcher's mound than deep left field. That was for the permits, installing new breaker box, pipe, meter box, ground rod, and running a 220 box to the furnace area. Never called anybody else. He put in a new heavier pipe through the roof, the breaker box, and a new meter box. Can't remember about the meter itself. He reconnected the old service wires. What I remember him telling me is the breaker box was better than what he usually put in, and he mentioned 200 amps. He said he forgot to put a "normal" smaller box in the truck and asked if I was okay with the big box he had. I said fine. He also used a big honking pipe going through the roof. About 3". Maybe because that's what hooked up to the box. It's all factory look, but I like it. You should see my computer case. Maybe he wanted to offload that HD stuff on me. Don't know.

The box is a 30 breaker box. I think the old box had 8 breakers plus the main. He asked if he could have them, because they weren't made anymore but he could use them and they were worth about 30 bucks each. Sure. He did some "unpaid" extra work for me, running conduit, a box and wire on a 20-amp to the back by my work benches I still haven't opened that box, and still use extension cords to existing outlets. He also split some circuits. So instead of 9 total breakers, the big box has 7-15amp, 5-20 amp, paired 30's for the HVAC, and paired 100's for the main. That's what they say. The next day the power company came out and ran new outside wires, and put a meter in. Soon after the village inspector came to look at everything. He didn't like that the lip of the breaker box cover is right against an overhead HVAC vent for about 4". But he passed everything. That could be fixed in 5 minutes with a Dremel, and I thought about it, but haven't touched it.

I had the tree guy out yesterday, and he said don't worry about the spruce branch barely touching the wires. No problem unless they put some weight on them, then call him if it looks like that. Says it can't happen for 3-4 years, if ever. Otherwise I haven't done squat else so far, and everything is working fine.