Strange electrical outage (house, not car)

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Strange electrical outage (house, not car)

August 05, 2009, 10:01:39 PM

The power in this area is notoriously unreliable, all it takes is a squirrel farting near a power post and it goes out, so I'm used to blackouts. I've never seen one like today, though. It wasn't windy, so it wasn't weather related. The strange thing that happened is this: Only one phase of my power went out. I was using my electric wood splitter plugged into my welder outlet (it's on its own breaker) and it stopped. I thought I tripped a breaker, but the shop stereo went out too, and it was on a separate breaker. I looked up and the lights were still on. I checked the breakers anyway and they were still on. I went into the house and the clock on the stove was working, but the range hood light wasn't. The stove light over the burners worked, but the one inside the oven didn't, and none of the burners worked. Kitchen , diningroom and livingroom lights were not working but outside light was. Bedrooms had power, office no. Fridge was dead, well pump was dead. I checked the house's main panel and everything looked OK. I did some more checking around and discovered that every other breaker in the main panel had no power. The kitchen outlets, which are split circuits, worked in one slot but not the other (IE the microwave plug worked, but the plug below it, in the same outlet, didn't).

The grey-out lasted about 15 minutes. My theory was that one of the two black wires coming from the pole was dead. I verified this by removing the breaker panel cover and testing for voltage where the wires come in from the meter (should be ~220 between the two black ones, and 110 between each black one and the white one, I had 110 between one of the black ones and the white, nothing at the other black, and nothing between them). I called the power company and they said they were not aware of any problems in the area. This leads me to believe that either the meter itself or the transformer on the pole is about to fail.

Any electricians here with any opinions?

Strange electrical outage (house, not car)

Reply #1 – August 05, 2009, 10:21:25 PM

Had something similar happen at my old place after an apparent lightning strike. We lost one phase, so basically 1/2 the house.
What was funny was when you turned the electric dryer on, the power came on to the rest of the house :p

Me and a buddy installed a new service entrance/meter into the house and all was well after the swap.

Strange electrical outage (house, not car)

Reply #2 – August 06, 2009, 12:18:59 AM

I had a situation a couple of years ago where the brightness of my lights kept changing. I put a meter on an outlet and the voltage was fluctuating between 110 & 130 volts.
The power company found the nuetral connection on their transformer was loose.

Strange electrical outage (house, not car)

Reply #3 – August 06, 2009, 01:17:23 AM

If you're the only one served by the transformer(I'm assuming no one else had a problem), then yes it's likely has a poor connection where that leg connects either at, or inside the transformer... Could also be a issue in the meter or it's mounting box(possible fire hazard)... I'd far rather drop a leg than the neutral... That puts all your L1 120v circuits in series with circuits on L2... Not a problem with say a couple 60w lamps in series, but pitting the refrigerator against that 60w lamp is sure death for the bulb...

Strange electrical outage (house, not car)

Reply #4 – August 06, 2009, 09:34:09 AM

The meter, box, main panel, and mast & wiring (and all the wiring in the house) were all new three years ago, so I don't think the problem would be on my end. The power company says they aren't aware of any problems, and the neighbours I've talked to didn't experience it, so I'm guessing it's the transformer. The transformer only serves my house - the two high tension wires on the pole have jumper wires into the transformer, and three wires come out of it and come into my house. There's another transformer the next pole down that services the neighbours' houses.

One other thing it could be: When I upgraded the main panel and house wiring to 200 amp, the electrician that made the final connection between the meter and the main panel (I'd have done it myself, but the power company insisted on being present so they could turn off the power, then turn it back on again when the final connection was made, and they would only do this if a licensed electrician was doing the work) told me that the wires coming from the pole should be upgraded, since they originally went to a 60-amp service. When the power guys came back to turn on the juice again and install the new meter they said the wires were fine. The electrician told me to keep an eye out for voltage drops (dimming lights, appliances acting up, etc), and I didn't see any in the first few months so I forgot all about it. Maybe it's time to stick a meter in an outlet and turn a bunch of stuff on to see if the voltage drops...

Strange electrical outage (house, not car)

Reply #5 – August 06, 2009, 09:37:39 AM

Quote from: Thunder Chicken;285483

(should be ~220 between the two black ones, and 110 between each black one and the white one, I had 110 between one of the black ones and the white, nothing at the other black,

Any electricians here with any opinions?

this tellls me it was power company equipment related. Typically transformers spend many years providing low line current on a phase (or should i say "a leg" if they are "about" to blow. IN your case, you had a momentary open on your single phase L1 or 2. When this happens, if it were electrical defects due to the xformer secondary or the meter base, you would have been having intermittant issues like this for quite some time.

I think the power company went to one of many MTS (switches located about every 5miles or so here in the states) and diverted power around a portion of the grid locally. The Manual Transfer Switch could be either a On / OFF / On pole mounted pipe system with blade contacts up at the cross arms and is opperated on the ground level.

Its designed like a blade disconnect / BBM switch (break before make or MBB-make before break) or just to open the circuit.

when your part of the grid was reconnnected, 15min is just about enough time for the power company to check thier work, discover one of the legs did not enguage. These Pole mounted switches look like a pipe mounted vertically on the pole with a handle at ground level. Flipping it up forces blades to land into power fingers up near the cross arm simiilar to our cheezy residential snap in breakers where the fingers could become a little over gapped.

WHen the power was switched back, one leg was prob absent and the manual transfer switch was retrown by the tech and it worked.

Take some laser temperature readings of the top side of your meter base as well as your main servce entrance breaker. ,, heat and corrosion coupled with the lack of use of NO-oxide on the connections will help wiring cook / corrode but you already know all that stuff. You might be able to duplicate what you were doing again on another day and see if this repeats itself. If your main breaker is allowing (through thermal conditions or high resistance) one leg to drop, then your main should be getting pretty hot. A laser temp reader could tell you if one side or the other is hotter(meaning your not load sharing correctly). what i am saying is that your main might have one of the contact closures heating up and cooling down acting like a thermal couple. Its not unlikely that the main might be the most probable fault.

im just adding to the opinion,, you dont magically have an open leg only to have it return back. A low leg up and down swings i could see but a leg coming up MIA only to return back tells me you must have some pretty high tech pole mounted xformers up there,,or someone had a hand in it.

Strange electrical outage (house, not car)

Reply #6 – August 06, 2009, 10:01:47 AM

Quote from: Thunder Chicken;285536

The meter, box, main panel, and mast & wiring (and all the wiring in the house) were all new three years ago, so I don't think the problem would be on my end. The power company says they aren't aware of any problems, and the neighbours I've talked to didn't experience it, so I'm guessing it's the transformer. The transformer only serves my house - the two high tension wires on the pole have jumper wires into the transformer, and three wires come out of it and come into my house. There's another transformer the next pole down that services the neighbours' houses.

One other thing it could be: When I upgraded the main panel and house wiring to 200 amp, the electrician that made the final connection between the meter and the main panel (I'd have done it myself, but the power company insisted on being present so they could turn off the power, then turn it back on again when the final connection was made, and they would only do this if a licensed electrician was doing the work) told me that the wires coming from the pole should be upgraded, since they originally went to a 60-amp service. When the power guys came back to turn on the juice again and install the new meter they said the wires were fine. The electrician told me to keep an eye out for voltage drops (dimming lights, appliances acting up, etc), and I didn't see any in the first few months so I forgot all about it. Maybe it's time to stick a meter in an outlet and turn a bunch of stuff on to see if the voltage drops...

what he meant (electrican) by voltage drops was..........
the loss across the wire when your inrush demand exceeded 70% of the wire ampacity rating.

No the aireal drop is not fine "if" engineered to your service size. However,, if you were never going to exceed approx 20-30A per leg, then it could be "arugued" that the aireal drops are ok. I hate the power company,,, you gotta near burn your house or company down just to get a "justification" to upgrade.

Since we could argue your wire size is cabled to the "application" and the application happens to be your historical power consumpiton dospoogeented in KWHrs used, its hard to argue getting a larger drop.

In the states, the power comany is responsible for labor/ costs associated the wiring to your aireal wether head. If its burried , then the homeowner usually shares any burden of labor having to do with the upgrade(since its considered "in raceway or cable tray" wire applications in conduit. Your a "free air rating" wire size so the wire can be smaller than conduit and be considered to carry much more current at 95 deg C.

The only way to beat this is to measure the out at the xformer then compare notes at your main.
In this case, the power company can be the cause of your fire,,as you know when voltage drops, current goes up.

Just think of how many electric bills you have gotten with instable voltages (if this is the case) were part of that power bill was due to unknown amounts of inrush and high current draw situations.

Strange electrical outage (house, not car)

Reply #7 – August 06, 2009, 12:08:50 PM

When I rewired the house I added electric heat, an electric clothes dryer, a built-in dishwasher, and an electric water heater. Although the electric heat is rarely used, the other items, not to mention the high-tech stuff hat the previous owner wouldn't have had (several TV's the smallest of which is 25", the largest is 36", two computers, a surround-sound system, water coooler/heater, A/C unit, etc) and the stuff in the garage (welder, log splitter, air compressor, etc) would have increased the household load dramatically. I know my first year's power consumption was double or more the previous year's readings (from the previous owner).

The pole-house wiring is sized for a 60-amp service, I would assume, since that is what was in the house when electricity was first connected to it 50 years ago. It looks like about 4-gauge wiring spanning about 100 feet from pole to mast, compared to the wires coming out of the mast, which are sized for 200-amp service and look like around 2/0 gauge. The electric company is aware of the upgraded wiring in the house (I had to get a permit from them). I hink it was more an issue of laziness on the part of the crew that showed up that day - they just wanted to flick a switch (and charge me nearly $200 for the privelige).

What the electrician meant by "voltage drop" was for me to put a meter in an outlet and crank on the electric heat, oven, water heater, etc to simulate a high demand (a demand like this would simulate, say, cooking Christmas dinner) and see if the voltage at the outlet drops too far. I forget the actual minimum he gave me (I'll have to call him and ask him) but it wasn't very much below 110, something like 105. Measuring at the pole would be impractical because I live on a major highway and my climbing the pole might attract unwanted attention. That and I'm scared silly of heights

The rerouting part of your theory sounds OK, except that none of the other houses in the area suffered the same outage. It was only my house, which has its own transformer.

I don't think weather was the issue - there wasn't a breath of wind, the skies were clear with no electrical storms around, and it wasn't particularly hot out (if it had been, I wouldn't have been splitting firewood!).

I'm wondering, Scott, if it may have been a thermal-protector in the xformer, something that might trip and then reset itself? I would have thought that both "legs" would have tripped, but if it was something faulty...

Anyway, I reported it to the electric company, and if i have any more issues they'll be certain to hear about it...

Strange electrical outage (house, not car)

Reply #8 – August 06, 2009, 08:58:13 PM

im a little confused trying to understand what happened here, did half of the service on the box go out intermittenly(or temporarily to be specific)?
the last time i remember someone dealing with a similar issue on an upgraded(100amp/200amp) service was the main breaker was faulty and shorted out half the box randomly, it was less than 5 months old.
it was confirmed by removing the main breaker and examining the clips from what "i" assume was too much of a gap between them and it allowed it to corrode and eventually start to short out that side of the box.
other than the wiring from the box to the telephone pole this the only likely thing i can come up with, hope this helps some.
bear in mind im not the guy who does this kinda stuff, been shocked enough just putting in outlets for people in houses with no grounds or same color wiring wraped in leather, and my terimoligy is a little elementary(duh, poles?)
all i know how to do is put it back on after they come shut it off, 'nuff said.

Strange electrical outage (house, not car)

Reply #9 – August 07, 2009, 07:53:27 AM

Half the box did indeed go dead, but it wasn't the main breaker. I pulled the cover off the box and tested for power where the wires come in from the meter and there was no power there.

Strange electrical outage (house, not car)

Reply #10 – August 07, 2009, 10:41:28 AM

First, I didn't read all of the replies. Not sure in Canada, but here, if it's on the pole, the power co. is responsible for checking it. Give them a call, and have them come out and inspect the transformer. If need be, they can inspect up to the meter. After the meter, it's up to you or a qualified electrician. In my experience, if something was to "pop" it would trigger the circuit breaker, and kill all power. When only one wire comes undone, it reduces the power like you experienced. Living in my trailer house, the wires underneath would come undone fairly often....a combo of improper burial of the lines and frost movement of both the wires and trailer. (I had 100 amp meter and 100 amp panel) But I'll vote transformer in your case.