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-   -   Lost 1 hot leg, need advice? (http://www.diychatroom.com/f18/lost-1-hot-leg-need-advice-150367/)

JamesB2136 07-15-2012 05:05 PM

Lost 1 hot leg, need advice?
 
A little back story...recently bought a home that was forclosed, starting doing some kitchen remodeling and some other minor repairs. When power company turns power on, all lights, outlets, ceiling fans, etc worked. The only thing I never turned on was the Central air unit, because I wanted to wait for a buddy of mine to some inspect it.

After inspection, he said the unit looked fine, so we powered on the breaker (push matic panel -Yes, I want to upgrade anyway-) and the unit seemed to run flawlessly. Quiet, cold, and he tested power draw at the internal battery and such. Everything seemed fine. 10 mins later, main breaker blew and took 10 mins to reset. Note on panel says to leave the double 30amp breaker on for 12 hours before actually turning on the central air unit. So I came back 18hours later and tried again. Blew main breaker again. Took 10 mins before main would reset. I checked all lights and such were still working. My contractors were doing a little more work in kitchen and went home for the night. Next day I came back to the house and one leg is out. Entire right side of panel (Older panel, not alternating breakers like new panels) is out.

Doing a little looking around, I noticed both ground wires were connected to a cold water pipe. Someone stole all of the copper from the house before I bought it, we replaced pipes with PEKS(PECS? it's like pvc)...so I'm assuming the technically isn't grounded anymore? Even though it is connected to the little part of copper that wasn't stolen? Hard to explain...The ground wires ARE touching copper at the moment, but the pipe that used to extend to street for water is NOT copper anymore...which makes me believe even though it's TOUCHING copper, it's not grounded???

Could that bad ground have caused me to overload the panel with the current draw of the central air unit, and in turn cause it to go bad and burn out one leg? (Side note: No other major applicances on in the house. No fridge, no computers, pretty much nothing cause house is empty)

Also, I had some guy (a self-proclaimed professional who's opinion I don't really trust) come out, while he was there I turned on the central air. The unit wouldn't come on (It's not getting full power due to one leg being out) BUT it seemed to send power up the dead side of the box, because lights and ceiling fans that were no longer working came on when I switched the central air open...kinda seems like an open ground to me? I don't know, i work on cars no electric lol.

So, Could the ground be the inital cause of the problem? So installing a ground bar (6ft deep) and a new panel with updated breakers fix my problem? I don't want to install a new panel just to blow another main. Anything else I should look for? Any other problems could cause something like this? Would it be worth looking into upgrading to 125 or 200amp service?

I appreciate any time you took to read my problem and help, THANK YOU IN ADVANCE!

EDIT: Power coming from roof and into the box is fine, it's not passing through the main causing the dead leg, checked that already.

McSteve 07-15-2012 05:32 PM

The main probably failed due to the repeated tripping, if you've got power on both legs into the breaker, but no power out of it, it's time to replace the main.

I can't stress enough that replacing the main breaker is not a DIY job, unless all power is disconnected by the power company first.

Don't try to turn on the AC again until it's serviced. Sounds like there's a fault in the AC or the wiring to it that's causing it to trip the breaker. Could be any number of things.

The water pipe bond has very little to do with the functioning of the electrical system. If the bond wire is no longer connected to at least 10' of metal water pipe buried in the ground, you will need to add a ground rod instead.

JamesB2136 07-15-2012 05:35 PM

Plan on installing the ground rod cause yes, the wires only attached to about 3' of copper piping now. I figured the tripping destroyed the main breaker. The initial tripping though, I'm not sure it was the AC cause I did have it serviced right before we turned it on for the first time, everything was checked. Wouldn't a fault with the AC trip the double 30 breaker instead of the main? I just don't want to install a new panel, ground rod and still have same issue. Thanks again!5

andrew79 07-15-2012 05:38 PM

No your panel is not grounded, that's one issue, you'll need to fix that as soon as possible with a ground rod or i believe you can bury a "ring" of wire that surrounds your house. Others here are far better versed in residential grounding than i am.
i think from what you've said so far is that when the breaker for the ac unit is on you liven'd up the dead leg of the panel, If the incomming voltage is ok then you have to assume that your main isn't making solid contact on one busbar. When you turn on the 240v AC unit your backfeeding the other side of the panel with that. The ac won't turn on because it's essentially getting 120v. Having it's breaker on currently is very bad for the motor. What may have happened to cause the problem is that the current draw from the ac was enough to cause a fault at an already worn main breaker connection.

I would advise getting a reputable electrician in to have a look if you can afford one. Do some research online. There's tons of sites that have reviews on service and whatnot. You could swap out the panel and give it a try as that's what you'll have to do anyways if you've got a bad busbar but that's an awfull expensive "whatif"

mpoulton 07-15-2012 06:04 PM

Quote:

Originally Posted by JamesB2136 (Post 966431)
Could that bad ground have caused me to overload the panel with the current draw of the central air unit, and in turn cause it to go bad and burn out one leg?

No. This is not a grounding issue. You may also have a grounding issue if you don't have any grounding electrodes anymore, but this problem is totally unrelated.

Quote:

The unit wouldn't come on (It's not getting full power due to one leg being out) BUT it seemed to send power up the dead side of the box, because lights and ceiling fans that were no longer working came on when I switched the central air open...kinda seems like an open ground to me?
The grounding system serves no purpose in the normal operation of your home's electrical system. It is there to protect against certain specific problems, but normally does nothing.

Quote:

So, Could the ground be the inital cause of the problem? So installing a ground bar (6ft deep) and a new panel with updated breakers fix my problem?
It's not the ground. Installing a ground rod (they are 8 feet long) will do nothing useful for you.

When you try to operate any 240V appliance, it backfeeds the other half of the bus through the appliance, thus giving you a little bit of power to the 120V appliances that are dead. This is a very clear indication that one leg of your panel is out.

Quote:

EDIT: Power coming from roof and into the box is fine, it's not passing through the main causing the dead leg, checked that already.
You've already diagnosed the problem. One leg of the main breaker is open. If you've tried opening and closing the main and it won't close both legs, then the main is bad and needs replaced. It's probably easier to replace the panel if the existing one is antiquated. It is also concerning that the main tripped instead of the AC's branch circuit breaker. If it were a dead short, then this lack of breaker coordination is not necessarily abnormal in a residential service. But it doesn't sound like a dead short, since the AC works for awhile before it trips, and the main won't reset for some time. This indicates a thermal trip from overload, not instant magnetic trip from a dead short. The branch circuit breaker should trip first. Is this a Federal Pacific Electric (FPE) panel?

The main appears to have failed because of a fault in the air conditioner. Definitely get that checked out and fixed. Just getting power to it again won't fix the underlying problem.

AllanJ 07-15-2012 06:51 PM

Quote:

Originally Posted by JamesB2136 (Post 966431)
A (It's not getting full power due to one leg being out) BUT it seemed to send power up the dead side of the box, because lights and ceiling fans that were no longer working came on when I switched the central air open...kinda seems like an open ground to me? .

This is a little phenomenon that happens when one leg of the 120/240 volt service is out and you switch on a 240 volt appliance.

Depending on how much stuff is turned on and drawing power on the "dead" side through the 240 volt appliance, the hot to neutral voltage on the dead side can drop much below 120.

The 240 volt appliance will not work correctly but it might start to come to life if enough 120 volt stuff on the dead leg was trying to draw power through it.

This phenomenon happens with or without a real ground.


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