I woke up this morning to an odd power outage at home. Half of the circuits in my house went dead. At 7:30 AM, the lights flickered and half the house went dark. I checked the breaker box and none were tripped, but oddly, it was an entire bank of circuits that were out.

With half the house working, I ran an extension cord to keep the refrigerator going and then after 45 minutes, everything came back.

It acted just like a power outage, but yet only in half of the house. I am at a loss.

Any ideas what could cause this? It's a 30-year-old home, but the circuit box looks brand new based on pulling the cover off for a quick look. Nothing looks out of place. Thoughts?

I'm guessing you lost a phase.
Generally speaking , you have two hots and one neutral coming from the pole to the house.
One of the hots wasn't working.

I've experienced this in the past when rodent damage caused a break in the wire at the pole end. In your case, I'm willing to bet that a protective device at the transformer tripped on that phase, and it took your power company 45 minutes to reset/replace it.

I've had one of the screws on one side of the main back out before. Caused half the house to flicker and killed my AC.

A bad main breaker will do it also.

Thanks, motor -- that makes perfect sense.

Mars, I did check for anything loose -- pulled the panel cover and did some checking. It's possible it's a bad main, but I like the phase outage idea. I am going to see if it repeats before doing anything drastic.

Call the power company.

If you lost a phase it could be on the pole or a much wider problem.

Either way they will need to fix it.

I had this problem at a building that this would happen a couple of times a year.

They rewired the area and fixed the problem.

I went through this at my sister's not long ago. Luckily before I got too far ahead of myself (I went expecting a lost neutral) I checked the incoming and it was dead. Power company came and it was a bad spice at the pole. They told her the other one was about to go as well so they did both.

If you have the ability to check for power coming in do so. The power company will probably ask if you've had an electrician check in the house first.

quote:

Originally posted by sig2392:
Call the power company.

If you lost a phase it could be on the pole or a much wider problem.

Either way they will need to fix it.

I had this problem at a building that this would happen a couple of times a year.

They rewired the area and fixed the problem.

Do this.

If you did lose a phase, then they would have likely fixed it for the power to come back on. If they did fix a problem near your house they will have a record of it. Mystery solved.

If they say no we did not fix something, then go to your neighbors house and ask if they experienced the same outage.

If they say yes, then call power company back and tell them they need to check connections at transformer.

If they say no, then call electrician to check for damage to breaker or loose connections at meter. If he finds no problem, back to PoCo to ask they check transformer connections. If you have no reason to suspect a problem on your side of electrical service then call PoCo first as they are free.

Feel for warmth around breakers and panel cover. If it's warm, it's your problem. An inexpensive thermometer gun is great for this too. Remove cover and measure all parts of panel focusing on connection points. All temps should be within 2℉ or less of ambient temperature.

Had a similar situation recently that turned out to be a service fault in the underground cable to the meter.

I also had this issue. turned out to be my main breaker lost a phase.

Something very similar happened at my house. There are two copper bus bars in my panel, and one of them was very lose. Just had to tighten up a nut to tighten it up.

Thanks again for all the replies -- all very helpful. I wanted to follow up. I did have an electrician out to make sure I wasn't missing any issue with the breaker panel. Everything checked out and there are no issues in the house. He agreed that the issue was on the power company side.

Thanks for everyone's help!

Happened to me. I went outside and saw one leg hanging off the transformer on the pole.

quote:

Originally posted by Mikito:
Happened to me. I went outside and saw one leg hanging off the transformer on the pole.

That must've been a horrifying sight. I wonder whose leg it was...

quote:

Originally posted by Balzé Halzé:

quote:

Originally posted by Mikito:
Happened to me. I went outside and saw one leg hanging off the transformer on the pole.

That must've been a horrifying sight. I wonder whose leg it was...

Did you contact power company?

If you lost a 110v leg from the pole you wouldn't lose one side of the panel since each leg alternates from one side of the panel to the other. That's how a 220v double breaker can get 2x110v legs to make it work.

quote:

Originally posted by Blackmore:
If you lost a 110v leg from the pole you wouldn't lose one side of the panel since each leg alternates from one side of the panel to the other. That's how a 220v double breaker can get 2x110v legs to make it work.

Whut?

quote:

Originally posted by stoic-one:

quote:

Originally posted by Blackmore:
If you lost a 110v leg from the pole you wouldn't lose one side of the panel since each leg alternates from one side of the panel to the other. That's how a 220v double breaker can get 2x110v legs to make it work.

Whut?

As you move down the panel it alternates "A" and "B" phases. All odd number breakers are A, all even numbers are B, for most panels. So you loose half the breakers, not one side of panel, but every other one instead.

quote:

Originally posted by Skins2881:

quote:

Originally posted by stoic-one:

quote:

Originally posted by Blackmore:
If you lost a 110v leg from the pole you wouldn't lose one side of the panel since each leg alternates from one side of the panel to the other. That's how a 220v double breaker can get 2x110v legs to make it work.

Whut?

As you move down the panel it alternates "A" and "B" phases. All odd number breakers are A, all even numbers are B, for most panels. So you loose half the breakers, not one side of panel, but every other one instead.

I misinterpreted what he said, regardless, you "basically" lose half your breakers... Which to most people is losing half the "panel", which not to say a side of it...

Well, we can wrap up the saga tonight. I dropped a phase again tonight at 9:08. I called the power company and had them out here at 10 PM -- underground cable fault. They had to bring in a different crew and I had the full rescue operation going at midnight. Two trucks, floodlights, 6 workers with headlamps. I'm sure my neighbors are going nuts. Power back on at 1 AM (they had to kill all power due to the bad cable). It should be fixed this time!