Power Quality - 30-60 Major Dips Per Day

How was your issue detected?:

Starting in August of 2020 I noticed intermittent lights flickering which were observed more frequently over time. Electric utility replaced meter, checked connections and declared the issue to be on my side. Flickering continued. Had three electricians evaluate my system and panels (1 main panel, 2 sub panels). No obvious signs but some discoloration in the main panel was seen and suggested main panel replacement which was completed in October 2020. The sub panels were not replaced. After main panel replacement flickering continued. Utility installed a monitoring device at meter and monitored for a few weeks and found no issues. Over the winter months flickering subsided almost completely. Starting in late March 2021 flickering returned. Installed the Sense device and commenced Power Quality labs monitoring and a typical day has been as shown in the attached images. Flickering has been on the increase. Utility came out and replaced service line from hand hole to meter in case of damage. No change. Neighbors are not reporting flickering in their homes. Although there are many homes on my street I am told that only my house and one other are fed off the line from the transformer and that house is not reporting flickering.

Did you noticed any other signs of this issue around your home?:

Not all lights/plugs in the house are affected when dips occur. When looking at the affected breakers it is consistent with only 1 of the 2 legs being affected which the Sense graphs confirmed.

Looking for ideas. Utility is going to return for further data recording at the meter and checking of their line from the transformer.

Screenshots from Sense Lab

L2 appears to be what is sagging. Can you post your power meter during these sag times? It would be interesting to see if the amps are spiking as well.

I should have also asked if the voltage for sense is coming out of main panel or one of the sub panels?

Snapshot with the following times/voltage circled.

2021-04-26T18:10:01.000Z 106.92
2021-04-26T18:12:01.000Z 107.46
2021-04-26T18:17:01.000Z 101.88
2021-04-26T18:19:02.000Z 100.92

@jim.humphrey01 Ok, the load looks pretty low during this time and I don’t see any indication that a big load is kicking on.

What panel is the voltage input for sense hooked into?

Typically a floating neutral will cause the voltage to go up on one leg and down on the other. Typically you see bright/dim which looking at the voltage profile it doesn’t indicate this. I wonder if you have a loose connection or bad breaker on a sub panel? I’m assuming the main panel has breakers feeding each sub?

Sense is hooked to the main panel. No bright only dips. The main panel feeds both subs off breakers in the main. Main panel has been completely replaced, subs have not.

Thanks for the info. Have utility check lugs and jaws in the meter base (hopefully they will do that when they pull the meter). It would be helpful to export the voltage dips as well to show the utility. Hopefully at the intervals that this is happening they can catch it while they are on site hence the reason to export the voltage sags.

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