Surge Stumper

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jeff43222

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Location
Minneapolis, Minnesota
I had a troubleshooting call this evening that left me pretty stumped. Single family house, 200A overhead service, feeding two 100A subpanels. Service is fed from a PoCo transformer that is the last one in the chain. The transformer feeds only this house.

The homeowner told me that they are experiencing power surges at random times, and they are bad enough that they showed me all the fried surge suppressors (they've gone through more than 20 of them). Before they installed the surge supressors, they lost a bunch of TVs, microwaves, telephones, etc. They had the dead ones stacked outside. The (many) circuits where these surges have occurred are all over the house.

My first thought was that instead of actual surges, perhaps they were experiencing a loose neutral on a multiwire circuit, getting a nice 245V internally to blow things up. But there were very few multiwire circuits in the panels, and none of the circuits in question was fed by one. I checked every connection in every panel, as well as the meter socket and the service point just to be thorough, and everything was tight as a drum. Voltage readings were all good in the panels and at the several receptacles I checked.

Adding to the mystery was that the main panel already has plug-in surge protection, and the indicator said it was working fine. PoCo has been out, and they claim everything is fine on their end.

The one thing in the house that made me suspicious was the well pump. They said they had it replaced a couple of years ago, and they problems with the surges started a couple months later. The wiring for the pump was shoddy and the grounding on it was poor to non-existent. I wondered if there was a chance the surges were coming from the well somehow and spreading through the house.

If it's not the well, then my guess is that there's still a problem on the PoCo side (e.g., loose neutral) that they will only investigate if an actual electrician calls them.

Anyone care to offer their $0.02?
 
My guess is not the well pump. I am willing to bet it is on the POCO side of things. Give them a call and have them check it again. I have heard of cases where the first time the check a service they miss things.
 
Remember the POCO supply to the house is a multi wire circuit in its self.

I occasionally have to call the POCO twice to get it resolved.
putting a test meter on it may make it appear its OK, so the POCO lazy butts will get back in the truck & head to a shade tree for a nap.
If you call again and get a better POCO tech he'll find the problem.
You really need to either be there yourself, or have the HO present when the POCO arrives & INSIST your premise wiring is fine.
Then call their supervisor for the area, Always a good number to keep in your file too.
Also call the POCO claims department to file a claim against damages after the first time you reported the problem.
They get the hint.
Squeaky wheel gets the grease!
 
My first hunch was also the service neutral between the transformer and the main panel, but I have no evidence that that's where the problem is. And now that I think of it, if the well pump had a problem with induced voltage, I think it would have been fried, too. Since the only stuff that is being fried is 120V electronic stuff, I think the loose neutral on the PoCo side is the most likely source of the problem.

So it seems that the consensus is that the problem starting a few months after the new pump was put in is just a coincidence. I'll call the homeowner and let them know I'll call the PoCo for them on Monday and demand that they do more investigating on their end.
 
I'd consider shutting down all the branch circuits in their house, and leaving a 20A circuit on. Load it like you stole it, and see if you can force open that neutral. Without any loads on the other phase, the risk of damage to the connected equipment would be minimal, I think.

Just a thought. :)
 
georgestolz said:
I'd consider shutting down all the branch circuits in their house, and leaving a 20A circuit on. Load it like you stole it, and see if you can force open that neutral. Without any loads on the other phase, the risk of damage to the connected equipment would be minimal, I think.

Just a thought. :)
Click to expand...

I agree with George.

Maybe you could watch the voltage when the pump cycles on/off (with the electronic circuits turned off).
 
I did set up an experiment where I watched the voltage on one of the offending circuits as the pump cycled. The highest it got was 128.4V. Then again, I didn't shut down all the other circuits in the house, so the problem could still be coming in off the pole.
 
Jeff,

If you can duplicate that set up, and watch the voltage both at the panel on each leg (both to neutral and to each other) and the outlet the electronics are plugged into, I think this may help point to where the neutral problem is. Either house side of panel or PoCo side of panel.

I (like others) believe it is a neutral problem.
 
The reason I think it's on the PoCo side is that the surging circuits are all over the house: some come from the main panel, some come from the first subpanel, and some from the second subpanel (both subs are connected directly to the main panel). I just don't see how it could be a neutral problem inside the house since it would have to be multiple neutrals with all the panels involved. That would be too much of a coincidence. One circuit I checked has only two receptacle outlets on it, and it is very close to the panel it originates from. So I was able to verify that at least one offending circuit has solid connections all the way back to the service point (I even climbed up on the roof and checked it).

Besides, I checked all three panels thoroughly and found absolutely nothing wrong. Everything was very tight, and my standards are high when it comes to tightness.
 
Jeff,
A couple things you might want to check:
You mentioned this house had 2 sub-panels, are the sub-panels fed from the outside disconnect box? If so, have you troubleshot the quad wire to the sub panel to see if any rodents, human errors, or anything that would have cut/damage the neutral?
In my lineman days in charlotte, I got many calls like this one you are working on. Trust me there are a lot of lazy POCO workers out there.
Here's a few things that they should look for and you could mention these or ask them if they checked so you can represent yourself to the customer as being professional and knowledgeable in your trade. Let's get real, the bottom line is the customer has a problem and they don't care who fixes it, they want answers.
One of the comments mentioned in this post was correct. If this customer lives in an area where there are squirrels, they are bad about keeping their teeth down to a minimal on the overhead neutral wire. Sometimes the amount of conductors they damage aren't easily seen. In some cases the are cut, but don't unwrap. The POCO man should look to see if what we called the "hot line" clamp is loose on the primary, this will cause major surges.
The also should have a device,(Beast Of Burden) that they can put in the meter socket that basically is a large hair dryer that has the ability to put load on their line side to see if a neutral is open. One thing that is a disadvantage is they are on the tx by themselves. A neighbor would be seeing the same problem if it were on the tx side. The POCO people also, when requested by the customer, can install a recorder to capture any activity within the customer's home.
If they POCO folks don't climb or get in the bucket to literally check every connection, they obviously have not done their part. As the electrician, you could start at the overhead attachment and read across the connections(with the house fully loaded) to see if there is a breakdown. I am not sure what type of meter you have, but one that reads in Mili-volts is very handy.
We were advised to start at the connections and work your way down the SE into the meter base,etc. I had one bad in conduit one time. A lazy electrician nicked or damaged the conductor, but hid it in conduit...in time, it went bad. Look to see if the SE neutral is corroded. You mentioned that everything was tight. I had one that was brand new install, but when they twisted the SE, it was too short to fit under the lug, but enough strands on the front side of the twist fit, appearing to be fully underneath the lug.
Not trying to insult your troubleshooting skills at all. Just some things I have come across in my career.
Does the customer have electric hot water heater? Not normally what a bad element would do, but possible.
I hope you get to the bottom of this. At first these kind of calls are challenging, but also can test you steam level
 
Steve,

Thanks for the ideas. I posted originally because I was stumped, and any information I can get that will help me solve this problem is much appreciated. The customer doesn't care how the problem is fixed, but since I spent five hours there the other day and found nothing, I feel like I have to pursue this with the PoCo so the customer doesn't feel like he spent all that money on me and got no solution.

The main panel is in the garage, fed with 2/0 Cu in PVC that runs out the back of the meter. The two subs are fed directly from the main with SER, and both subs are located just inside the house near the garage. I didn't see any damage on anything. My thinking is that the problem must be upstream of the subpanel feeders since there was at least one circuit coming from the main panel that was affected by this. If the feeder neutrals were bad, it shouldn't affect the circuits in the main panel, right?

I just got off the phone with the PoCo, and they said they are going to install the 'beast of burden' and check all the connections on their end. They will also install a recorder to monitor the voltages. They agreed with me that the problem is most likely a loose neutral. When I mentioned the possible loose hot line clamp, they said it wouldn't cause surges.

My main meter is a Fluke 337. It shows volts to 0.1V, but not mV. I don't think I need anything with more sensitivity since I don't do electronics.

If the PoCo says everything is fine on their end, I think my next step would be to dismantle the connection from the meter to the main panel and examine the wiring inside the conduit. I suppose it's possible that the wires might have a nick in them that could cause this.
 
I'm lost...
Let me see if I got this right.
Main panel in garage with 2 sub main breakers with SE cable to 2 seperate locations.
Now, the Meter is not next to the Main Panel in the garage? It is underground in PVC with 2/0 & where is the meter? how far away from the Main panel in hte garage?
 
The meter is outside the garage. PVC runs from the back of the meter through the wall and down into the top of the main panel. The outside part of the garage has a higher grade than the inside, but as far as I can tell, nothing goes underground at any point. The meter and main panel are very close to each other. The two subpanels are just inside the house, about 10' from the main panel.
 
I had a similiar problem at my Mom's house. The lights would get "BRITE" when a few items would turn on .. micro;dishwasher;washing machine;a/c .. everything tight on inside of house .. I even went into numerous boxes to check connections .. nothing wrong .. .. then I went outside to have a smoke (no smoking in house) and standing under a tree to keep out of the light rain, I happened to look up and see some "Bird-Droppings" on the incoming service drop .. got a ladder and found where the crap was concentrated the most, the Neutral wire was corroded to the point where the "messenger" and 2 strands were left .. called the PoCo and they within 3 hrs were there to inspect .. found the problem also; put on a "Jumper" temp and returned 3 hrs later to change the drop .. problem solved and many thanks to PoCo for prompt service (Detroit Edison) ... ... you did say it was an overhead service ... look CLOSE and you may find ... M
 
FYI>>>Another symptom of this loose or broken neutral is customer reporting a shock when in the shower & touching the CW faucet.
Neutral will conduct thru the bond to CW pipe.

What?s amazing is just how does the overhead drop disintegrate in the middle of the line?
 
Mike Holt has video titled "Open Neutrals". The POCO is shown with a special meter that detects open neutrals.
By the way very interesting video, there were three fires from open neutrals, due to phyrophoric carbonization. The current was trying to get to its source via the wood in the house and over a long period of time dried out the wood, turned to charcoal, and started it on fire, from around 10 volts or so.
See if your POCO has the special meter
 
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