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Discussion Starter · #1 ·
Need some quick help, as I'm lost....and more importantly can't use the theater!!


Heard the outdoor AC unit having problems trying to start up last night a couple times. It finally kicked on. This afternoon, I noticed it getting warmer in the house and sure enought, the thermostat was calling for AC, but the outdoor unit was off. Checked it out, and the motor is turning slowly..so probably a bad motor, or bad start CAP. Called the AC guy...could be days I'm guessing.


Go inside and raise the temp of the thermostat so the unit doesn't run like this all day, and as soon as it clicks the AC off, half of the house (including the theater) go dark. Blew a breaker I think, so down to the panel. Nope all good. Reset the main and each indivuidal one. Still no power in half the house. For the heck of it, I set the AC temp down, and it calls for it to come on again...and Bingo all of the power back. Let it run for a few minutes, and turn the temp up and as soon as it clicks the AC off, 1/2 the house is dark again. If I throw just the AC or the compresor breaker or kill the power switch at the blower unit, I get the same thing. What the heck is going on?
 

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Call an electrician. If you switch off the A/C at the breaker and half the house goes dark, somebody messed up your breaker box.
 

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Is the half of the house that goes dark all circuits that reside on one half of your breaker panel?
 

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Discussion Starter · #4 ·
It appears that the 1/2 that go off are the ones on the opposite side of the double breaker for the AC Compressor.
 

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You lost one of the ac legs from the power company

You breaker box is fed by 2 different 110 volt feeds from the power company. Half of the breakers are on one...half on the other

Big things like your ac compressor (outside unit) and an electric dryer require both legs


I'd call the power company
 

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definitely call an electrician first, before ac repairman.


i believe you may have faulty wiring (duh), but more specifically an open neutral.


the wiring for the AC is probably good, and of enough gauge so that it is competing the return path when the motor comes on (there is no neutral to affect it only 2 hots and a ground, it is probably returning via the ground).


it is potentially a deadly situation in the house as some circuits will appear dead but will actually be hot, but missing a return path. it is also indicative of course of some wiring fault somewhere.


not saying this is what you have, but it is at least complicated enough to require an emergency electrician to come out. and it doesnt sound like you have a meter or the know how to track this down...
 

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Quote:
Originally Posted by bcrawfo2 /forum/post/0


You lost one of the ac legs from the power company

You breaker box is fed by 2 different 110 volt feeds from the power company. Half of the breakers are on one...half on the other

Big things like your ac compressor (outside unit) and an electric dryer require both legs


I'd call the power company


If you ac being turned on allows the "other" half of your house to light up. I think the ac motor is bridging from the working 110 feed to the non working feed


Where are you located? Maybe one of us could come look with you?
 

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Sounds like one leg of the ac feed coming into your house is not working. I had a similar issue with with a sub panel in a detached garage. If you feel comfortable working with electricity you could use a multimeter and bridge the red and black wire and if you are getting 240 you are good. If you get 120 you need to call the power co. If you have any hesitation about working with electricity I would say do not attempt this. Call a electrician.
 

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Discussion Starter · #10 ·
Thanks for all of the replies. We are in Cincinnati, Ohio...House is 15ish years old so we have breakers. As noted, I reset both the main and all of the other breakers. If the breaker for the AC is off, or I turn it off by the thermostat, 1/2 the circuits dont work.



RIght now, The AC is on, the fan is barely spinning, and while all of the circuits in the house are "hot" any fan or flourescent light don't seem to work very well at all. I wonder if it is becuae the AC is constantly trying to kick on. Or Could this still be an issue with one of the lines coming in to the house? I don't see how 1/2 of the circuits woudl work at all. Will call an electrician first thing in the morning....hope he doesn't tell me its a bad AC and call that guy..


I'm going to move a few fans and lights to circuits that work all the time and kill teh AC feed for the night. It makes me nervous to have it on and calling for AC with the fan barely spinning and the compressor not comign on.
 

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I agree with others, get an electrician out if you are not comfortable testing yourself. If you are comfortable and have a multimeter, throw the main breaker and test each side of the feed from your street. If one of the two is not working, then it may be your power companies issue to deal with. If there is 120 on each of the feeds, then it is within your house or panel.


Hard time to be without AC. Good luck.
 

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Best thing is, most Electricians also can do A/C, so you can call one company and they'll probably send out two people to diagnose and cure.


I had to replace an A/C unit this last year and the company I called did it all, including re-doing my living room with two more 120's ran into a closet.
 

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Quote:
Originally Posted by barhoram /forum/post/0


Thanks for all of the replies. We are in Cincinnati, Ohio...House is 15ish years old so we have breakers. As noted, I reset both the main and all of the other breakers. If the breaker for the AC is off, or I turn it off by the thermostat, 1/2 the circuits dont work.


RIght now, The AC is on, the fan is barely spinning, and while all of the circuits in the house are "hot" any fan or flourescent light don't seem to work very well at all. I wonder if it is becuae the AC is constantly trying to kick on. Or Could this still be an issue with one of the lines coming in to the house? I don't see how 1/2 of the circuits woudl work at all. Will call an electrician first thing in the morning....hope he doesn't tell me its a bad AC and call that guy..


I'm going to move a few fans and lights to circuits that work all the time and kill teh AC feed for the night. It makes me nervous to have it on and calling for AC with the fan barely spinning and the compressor not comign on.

I was trying to quote your question about why half of the circuits work


Again...you have two hot feeds coming in from the street. Once in your box, the two feeds weave and alternate inside the box. This is done to distribute load across both phases as you grow and to allow you to plug in 220 breakers (that use both phases)

Next time you are at home depot, the should have a display that will let you see this. It will hopefully make a lightbulb in your head come on


Your ac has a breaker on both phases, but we believe is only getting power input on one. The motor is feeding back SOME power on the bad phase when he is trying to run

Some devices with picky power requirements (fluorescent) may not like this fed-back power. It could be bad for your computer power supply and your ac compressor motor


Good luck and let us know
 

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Discussion Starter · #14 ·
Again, Thanks for all the help. Pulled the panel cover and checked with my meter. 120V one phase to Ground, 85V the other phase to ground, 207V Phase to Phase.

Have a call in to the power company. They should be here over the next 3 hours. Trying to find out of the undground wire are thiers or ours....and if the neighbor replacing thier driveway several days ago had anything to do with it. They did mark before they "dug"
 

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Quote:
Originally Posted by bcrawfo2 /forum/post/20789995


You lost one of the ac legs from the power company

You breaker box is fed by 2 different 110 volt feeds from the power company. Half of the breakers are on one...half on the other

Big things like your ac compressor (outside unit) and an electric dryer require both legs


I'd call the power company

I concur with this, the power co. should be the first point of contact as you have indicated you have done barhoram.


We had the same thing happen but at work which has 3 phases coming in. We lost one leg (R.I.P. little squirrel)and the flourscent lights were flickering on and off, elevator and A/C would not work, etc.


In the meantime I would suggest that you shut off anything that uses the 2 phases like you a/c, hot water heater and so on, as it could cause damage to that equipment resulting in some costly expenses.
 

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Discussion Starter · #16 ·
Power Co. was just here. Worst case. Problem with the underground line between thier box and the meter (our problem). Break looks to be somehere under the concrete driveway....does not look like a conduit was run. 100 feet or so.... Anyone know a good electrician in the Cincinnati area for underground work?
 

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Couldn't you just get someone to run a new conduit under the driveway so you don't need to dig it up?
 

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Quote:
Originally Posted by barhoram /forum/post/20791463


Power Co. was just here. Worst case. Problem with the underground line between thier box and the meter (our problem). Break looks to be somehere under the concrete driveway....does not look like a conduit was run. 100 feet or so.... Anyone know a good electrician in the Cincinnati area for underground work?

I don't work in Residential electric but I do work with Industrial power delivery (Im an EE). If it's going to take a long period of time to get this repair done right perhaps a temporary conductor can be ran from their box to your meter. Again, I'm not aware of proper codes or what is permissable in residential applications but I know I've done some temporary drops that had more laxed codes because they were temporary. You might have to mark off the area with caution tape or something.
 

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Is that between the transformer and the electric meter? I have worked for an EMC for 28 years and I have never heard of that being the customers repsonsibility to repair. I guess different states have different regulations. Did they offer to install a servi-safer. That is a device that can take one phase and split to two at the meter base until the other cable is repaired.
 

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Quote:
Originally Posted by jntart
Is that between the transformer and the electric meter? I have worked for an EMC for 28 years and I have never heard of that being the customers repsonsibility to repair.
It varies by utility. Some utilities will maintain any service connection, up to the point of attachment to the house. Other utilities will only maintain overhead service drops, and require the customer to maintain underground service laterals due to the increased cost.


I don't know who provides the electric service to the OP's residence, but the Duke Energy (Cinergy/CG&E) electric service manual does say "The customer will furnish, install, own, and maintain all new service laterals." (Lateral being a distinction of underground facilities, as opposed to service drops which are overhead facilities.)
 
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