Strange power failure at the house this morning.

[MarkF48]

Faulty neutral. When the compressor kicked on it couldn't find a good return for the current through the neutral so it followed the path back through the other leg of the 120 supply which your electronics was on. Since the "resistance" of the compressor is low and the circuit leg that had the electronics on was likely high, the voltage imposed on the leg with the electronics went to a high voltage and toasted your stuff.

I had a similar situation a number of years ago with a table saw that when it was switched on would kick up the brightness of some lights on an opposite 120 circuit leg. Neutral wasn't making a good connection at the street transformer.

 

[grsthegreat]

Yes, have seen it many times over the years. You have a dropped neutral underground.

As stated above, youve lost the return path for the current.

Its nothing inside the house. Usually when this happens, some appliances get fried. If the utility company in your area is responsible for the wire from the meter to their transmission facilities, their insurance should take care of your fried equipment.

Otherwise time to contact your insurance company as you'll likely find damaged tvs, fridge, freezer, ac or heat units, etc.

 

[uglyboywith11fingers]

thanks for all opinions... not necessarily what I wanted to hear.
I agree with the open, or bad connection on the neutral, but in my mind I would have suspected a bad connection somewhere, rather than a problem with a straight run of wire.
Have found no other damaged electric items... I guess all other really sensitive stuff was on the phase that went low voltage, although that can be a problem too with motors, etc.

I'll update after the next step in the investigation.

Pete

 

[Soundguy]

I'm surprised the computer bought it. Triac/switching power supplies are generally very, very tolerant of voltages in the 90-240 range....

 

[kco]

Hope this is appropriate for this forum, after all, we are rural.
This morning I was out in our attached garage, using my air nailer/stapler to slap together some free-standing shelf units for my daughters basement storage area.
The air compressor (120v) kicked in, then started to stop & start and finally just buzzed. I quick like a bunny hit the switch, and started to scratch my head, when wifey burst into the garage from the house, telling me the computer was popping and fizzing and smoking. Into the house I go, smells like burnt electronics, so I grab my multi-meter to check the power. One phase is at 147volts, the other at 93volts.
I quick went for the main switch. After thinking about it for a minute, I opened the main switch box, and checked things out with the multi-meter. with the main sw. off, both phases are at 120v. Turned on the main sw, back to the 147 & 93 situation... so I left it off & called the power company.
Well, they checked things out & tell me they think the problem is with the underground service wiring from meter box to the transformer at the road... about 200 feet.
Likely a problem with the neutral, they say. They say that repeated frost heaving over the years (house built in mid 1960's) has probably damaged the wiring, they suspect the conductors may be direct buried, not in a conduit. They are in a metal conduit going into the ground from the meter box. 100 amp service, by the way.
They left me with some neat transformer/gizmo attached at the meter box which apparently can stabilize the power even if one of the conductors, hot or neutral, is completely open.

So, we have power again, and a different crew is scheduled to come out and further diagnose our predicament. So far, 2 PC's dead, laser printer dead, digital light timer dead.


So I have a couple questions for you power experts on the forum...

1. What do you think of the diagnosis so far ? A few years ago, my neighbour across the road who is on the same transformer, had power fluctuations that required the utility to replace the Y crimp-connectors up at the transformer, that connect both our houses to the transformer. Apparently an overheated connection. At that time we had not noticed any power fluctuations. My limited knowledge would lead me to suspect a bad connection somewhere rather than a sharp rock or something underground intruding on the service wiring.

2. I'm in Ontario... who is usually responsible for repair/replacement of this underground service wiring if that is the problem ?

thanks for any opinions,

Pete

If it is like utilities I worked for in Manitoba and Alberta I think the utility will be responsible for the repair. They should own everything up to where your wires connect to the service wires from your house. I imagine you own the entire meter socket and they own all the conductor from the utility side of that socket back to their system. So the utility should be responsible for repairs on the source underground cable.

I think it is similar where I now live in BC. I have an overhead primary service with a transformer near the house. My house service runs to an outside wall, through a meter socket, and in a conduit to a mast on the house. The utility owns the conductor from the transformer pole to the conductors coming out of my service mast. I own the entire mast and conductors in it.

A surge protector would not have prevented damage to your computers and electronic equipment for this broken neutral condition, but a good uninterruptible power supply should as long as the computer, etc is connected to the UPS outlets. Most UPS's have switched outlets that supply power during an outage and other outlets providing simple surge protection.

I have a 1500 va UPS but just connect my file server and internet router to the switched outlets. My PC and monitor, external disks attached to the server, etc. are on the surge protection-only outlets. The main thing for me is to protect server data. If we are home during and outage I shut it down with a tablet. We can then still use the internet router to check estimated restoration times on BC Hydro's website, plus we can surf the net in the dark.

It's important to completely shutdown everything if you detect an unbalanced voltage condition like you experienced. While the frying due to over-voltage is noticeable, the under-voltage (as experienced with your compressor) can burn out motors on fridges and freezers.

 

[JPRambo]

I have also seen this here many times. Here it usually is overhead neutral wire that get disconnected from the pole mounted transformer.

 

[uglyboywith11fingers]

kco & JPRambo... I like your thinking. I'm hoping it's a bad connection up near the transformer. There have been a lot of power outages in the Greater Toronto area lately, it is being blamed on winter road salt spray getting blown up near the top of utility poles, and causing poles fires when it rains... I guess the wet salt turns poles & insulators into conductors.

I really hope they don't have to replace the underground conductors. As near as I can figure, it's a straight run from side of garage to the road, probably about 6 feet off the driveway.
There are still 4 foot snowbanks along there. Would make for a BIG mess.

Pete

 

[PILOON]

kco & JPRambo... I like your thinking. I'm hoping it's a bad connection up near the transformer. There have been a lot of power outages in the Greater Toronto area lately, it is being blamed on winter road salt spray getting blown up near the top of utility poles, and causing poles fires when it rains... I guess the wet salt turns poles & insulators into conductors.

I really hope they don't have to replace the underground conductors. As near as I can figure, it's a straight run from side of garage to the road, probably about 6 feet off the driveway.
There are still 4 foot snowbanks along there. Would make for a BIG mess.

Pete

Surely a temporary solution is possible such as either a line slung from the pole to a an eave near house entry point.
When they build houses temps are used all the time.

Then again the whole lead in replacement cabling could actually simply be uncoiled and laid over the snow to await later burial.
That lead in is waterproof and rugged enough to withstand just about everything except direct impacts.
Were I you I'd ask about this option but suspect once buried you would need to call in an electrician to adjust the length and re connect to the meter.
Might cost couple $$ more but would be less messy.

 

[cqaigy2]

I'm surprised the computer bought it. Triac/switching power supplies are generally very, very tolerant of voltages in the 90-240 range....

I would have thought so too. The smoke got released from both the monitor and computer because of faulty neutral.

 

[Soundguy]

the monitor i can see. the computer is just darn odd. many switcher supplies don't even need a dip switch to go from 110 to 240. they just auto aperature. IE. the triac looks at a smaller slice of the wave. that makes them nice. 90-240vac is usually FINE for them.