Need Electrical Expertise

Electrical problem in our house - brick 3br, 2ba, built on a slab - 10 years old.
Underground utilities, no poles.

This has happened 6 times in the last week. Back half of house goes dead - master bedroom, green bedroom, kitchen, dining area, both bathrooms. Front half of house okay - living room, blue bedroom, garage, hallway.

The first time it happened, I called in a handyman we had used before. He told me to turn on all the ceiling fan and light switches in the dead rooms before he got here. We were standing in the short hallway between the green and blue bedrooms and he asked me if the AC worked. The thermostat is right there and when I turned the AC on, immediately everything came back to life. It was obvious because the switches were all on. He then pulled the front panel off the breaker box, checked tightness on all connections, did the same on the furnace/AC unit, even went up in the attic and moved around any wires he could get to, looking for a possible loose connection. Everything appeared fine.

Here is the weird part - every time this has happened (same dead areas), all I had to do was turn the AC on and everything was immediately back to normal. The times of the outages appear to be random, once at 4AM with everything off, no AC or heat.

Any ideas? This is driving us nuts.

You could start by calling the power company and having them check the supp;y line coming into the house/meter.

You have a supply problem. If you know your way around a panel box you can check your incoming power yourself.

Thanks for the response, but I don't think that is it.

When there is an episode, the front half of the house has normal power. It seems to me if there were a supply problem then the whole house would be affected.

Not quite....

You have 2 hot lines coming into the house. (That's how we get 220 volts)

One of those lines is having an issue.

The 1/2 of the house is what leads me to this conclusion

Agree with Gizmo - your load center isn't working right.  The fact that running the a/c makes things right again (for awhile) makes me think the problem may be in the neutral connection rather than one of the two "hot" buses/wires. but it all needs to be checked out.

Your power utility will test the service up to the feed to the house. Some will go all the way to the load center, while others stop at the street connection (because you own the service entrance and they won't work on stuff that is not theirs).  The load center and house wiring is all yours, but some electric utilities willat least test for you. If not, you will have to hire a well-trained and skilled electrician.

Thanks to both of you - what you say makes sense.

When my handyman was up in the attic, what he was hoping to find was a junction box where inside of it was a loose neutral. Needless to say, no go.

A faulty neutral feed can often be detected by measuring voltage on the two hot legs. One goes high (well above 120v) while the other goes low.

If you have underground utilities, doesn't the power come up from the slab to the load center? What's in the attic? Should only have branch circuits for ceiling lights up there.

Gary, the incoming power comes out of the ground about 6 inches outside the garage wall and runs up the exterior wall in a 3" pipe directly into the meter. The breaker box is in the interior wall apparently lined up with the meter.

I think Gary may be right. With the recent debate on 30/50 amp hook-ups I can see that large loads may well be 220 volts and other items like lighting and sockets are 120. When you switch on the A/C, as it uses both lives it will create an artificial neutral (0 volt reference point) Look for a bad neutral connection.
TonyL

Get a qualified electrician in there before your house burns down. Your handyman might be good for hanging pictures and the like, but he's way out of his league on this.

Tony, when you say look for a bad neutral connection, is it likely to be outside, prior to the breakers or inside the wall and on or after the breakers?

The reason I am asking this is when I hire an electrician, will he work outside the wall or will he only work on the inside?

Will I have to have the power company look at their part first?

I really doubt a bad neutral is causing the problem but it is cheap to check. Go to the incoming panel and shut off all the power with the main breaker (usually the one that says 100). Then take a screwdriver and tighten all the white wires on the neutral buss.

Do this. Identify the circuit breakers that power the "non-working" parts of the house.  NOTE the pattern.. if they are PUSHMATIC (push push) breakers are they all on the same side of the breaker box.

IF they are Lever action breakers (like Square D which is common in RVs) are they all even or odd numbered?

Note  by even and odd number I mean counting from teh top
1  7
2  8
3  9
4  10
5  11
6  12

This is the pattern

If they are numbered
1 2
3 4
5 6
Use the firt pattern for lever action breakers and the 2nd for Push Matic

I am going to take a guess that this will be the case.  If not. Just stop reading this post here.

What I have described is L-1 and L-2.. The two legs of 120/240 volt service

My THEORY is you will find the non-working half of the house is ONE LEG and the problem can be any of the following

The main breaker connections (Already checked by your technician so not likely)
The connections on YOUR SIDE of the meter (If this is the low probility case the power company WILL bill you but not overly so)
The connections on their side of the meter (Rules vary depending on power company)
The connections at the "Top" of where the "Drop" connects to your house (Power company responsibility)
The connections at the transformer (power company's problems)
Faulty transformer Also power company's problem

Rare but posssible  Bad meter  Power company's problem

I recall one time a campground I was stuck in half the park went dark including the water pump.

Well working with the park owner I determined... It was BEFORE the meter. making it a power company problem.. and their technician 1: Confirmed and 2: Fixed.

You say the back half of the house goes dead.  How many branch circuits is that and has anybody looked at the load center to determine whether they are all on the same bus (leg)?  And whether anything else on that bus (leg) still works?  That isn't hard to determine, but requires some knowledge of the load center layout.

What other 240v appliances are there besides the a/c, and do they also affect the problem? Also, is the a/c powered from the load center that serves the rest of the house, or does it have its own panel somewhere?  For example, my property has a main panel that feeds three sub-panels, one of which is the entire house, one the heat pump, and one my separate shop building.

To Gary and all others who chipped in.

THE PROBLEM HAS BEEN FIXED.

The power company just left. It took him one minute to find the problem and about another 15 to fix it.

He said that when the subdivision was laid out, they come in and trench in all the lines. They run the lines into the same large plastic box that contains the water meter and pressure regulator. Then when the house itself is going up, they put in connectors in that box and run the lines underground to the meter.
One of those connectors on one leg had burned up. I  asked him how the AC could still run with one leg dead and he said that with a partial connection or no connection, there would be an arc and that would essentially weld the wires together enough for continuity. That plastic box is in the front yard near the curb and he parked on the curb, walked up to the box, lifted the lid, lifted one of the cables up and said "here is your problem". The box itself was 3/4 full of dirt and he had to bang the connector on the box to get dried mud off of it and so being sometimes buried in mud probably led to the problem.

Anyway, the connector was replaced and all is good. The best part is no fire danger and the fix was free.

Thanks again.
Bill

arcticfox2005 said:

The best part is no fire danger and the fix was free.

Click to expand...

Thanks for the followup and glad you got it fixed

As I said. That was my FIRST Suspect.  Glad you got it fixed. Though I'm not always glad to be right.

OH. somethign like that happened at my house as well. only it was the neutral not a leg (Now that's scary) cost me some minor repairs once we fixed it.