Backfeeding?

newbiehomeowner · Nov 3, 2005, 05:16 PM

I have a problem with the electrical wiring in the house I bought.. or several problems. The home inspector pointed out to me before I bought the house that there were 4 -110V circuits in the mail electrical panel that had been doubled up on the breaker and needed their own breaker. Seemed like a simple problem. He also pointed out that most every outlet in the house had the wrong polarity. Funny I thought AC voltage polarity changed at 60 hz. he said I should be able to fix these myself by disconnecting the breaker to the circuit, verifying that there was no voltage present and open the outlet behind the wall plates and switch the wires. I have yet to do this, and hope it isn't related to the biggie problem that has recently surfaced. So, I hired an electrician to address the breaker problem and he put in mini breakers which take up one space in the panel box and will accommodate two circuits since there are no more blanks in the breaker box. He came across one wire which he attempted to put on its own breaker and it tripped the breaker when he energised the main. So he said, this circuit is back-feeding, and he put the wire back where it came from with another on the one breaker... hmmm... So I paid him and he left. Everything has been working fine albeit the 300 dollar monthly bill this summer with the centraal AC running. When one day, I noticed that the condensing unit outside wasn't running and went to the thermostat to see if it was calling for cool which it was. I checked the outside disconnect by the unit and it had not tripped off, but reset it anyway and went back inside to set the thermostat to call for cool. The outside unit still did not come on. I did not check the voltage at the condensing unit. I did not open the cabinet and check for 24V at the contactor. I then, raised the thermostat to 90 so it did not call for cool and.. (here the weird part) the entire screened in porch section of the house went dead. All of the outlets had no voltage present. I then went back to the thermostat and lowered the temp to call for cool and the room was energized again. I feel like there is a problem in the air handler where the blower unit is, where the low voltage transformer is usually located, but do not know exactly where to begin to troubleshoot this weird phoenomena. So I suffered in the heat of the last month and a half of summer without AC... It is a Heat Pump, and cold weather is fast approaching, I switched off the breaker at the panel box.
Any Ideas?
Thanks.
Neil

hvac1000 · Nov 3, 2005, 06:08 PM

Sir. You have a major electrical problem that I am afraid is going to be too much for you to take care of. Call the electrician back that worked on the system to start with and have him fix it correctly.better to be safe than sorry.

labman · Nov 3, 2005, 07:27 PM

HVAC may be right. One thing to check. Do you have main fuses? If one blows, and you have any 240 volt devices running, power can back feed from the hot leg through the device and back to the box, and from there, to all the circuits on that leg. All sorts of strange things happen. I have run into to it, and it took me a long time to figure it out the first time. The second time, it took me longer to get the guy shut up and show me the fuse box, than to fix the problem. He bragged on me for the rest of his life. I think breakers are built that when one side goes, they both should disconnect. Doesn't say one side couldn't happen. The problem could also be bad connections. If power for half the house the house is trying to feed through the heat pump compressor, that could be why it doesn't work. Other than checking the fuse if there is one, the main breaker box is at least very close to where the average homeowner needs to call professional help. You could at least try shutting the main breaker clear off, and then firmly pushing it to on.

As for the wrong polarity, you are correct, AC reverses poles 60 time as second. However, houses are to be wired in such a way that as you look at an outlet, with the third prong down, the longer slot on the left is the grounded neutral and the shorter one on the right is 120 volts above or below ground. The 2 legs of the system will be of opposite polarities. The instructions on shutting the power off and pulling the outlets were a good start. Once out, the white wire should be connected to the nickel plated screw, and the black or other non green color connected to plain brass one. The bare or green ground wire should be connected to a green screw on the outlet frame.

newbiehomeowner · Nov 5, 2005, 02:27 AM

Labman , thanks for the reply. Actually the home inspector pointed out from the scuttle hole in the garage with his flashlight, clear down to the opposite side of the house , a box, which would normally house edison type glass fuses , which have been outlawed here in Florida. He did not take the time to crawl through the attic and see whether it was "live" or had been btpassed. Now after reading your post, I am beginning to believe that it is live. There is a 220 feed housed in PVC up there going in that direction, which is the direction of the condensing unit. There is a secondary building in that direction also , which I understand has or had 220 in it for a welder. I use 110 in that building. The building stayed live.
I agree that this circuit needs to be investigated by a qualified electrician. Any idea on what is a normal time frame for an electrician to troubleshoot this particular problem?
Thanks again,
Neil

hvac1000 · Nov 5, 2005, 05:35 AM

A good Sparky (electrician) should be able to figure this out in one hour or less. BUT like anything else it could take longer depending upon weather he has free access and nothing has been hidden by walls ETC.

labman · Nov 5, 2005, 08:23 AM

A fused sub panel with one blown main fuse could create the same strange problems on the circuits it feeds. Depending how creative whoever did the wiring was, and how much nonsense is hidden somewhere hard to find, who knows how long it may to identify and fix the problems.

newbiehomeowner · Nov 5, 2005, 11:02 AM

Thanks again for the replies. Looks like I will have to get my big-*&$ up there with my FLuke and see if in fact the box is live and take a glass fuse (or cartridge type) with me to get some heat until I can get an electrician out here... meanwhile.. now I need an education in adjusting the high side and low side pressure switch to the well... seems as though it is beginning to short cycle... welcome to home ownership..

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