[Power Quality] - 1000x Dips and Spikes in 3 Days


I am trying to work out why I am getting 1000X Dips and Spikes in three days.

Try to post a screenshot or two of your Power Quality. You can even download and post the CSV file, and we can try and give advice.

power_quality_raw.csv (38.7 KB)

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Yikes! If you are experiencing any issues in your home or if you can in any way confirm these are actual spikes & dips & not an issue with the Sense monitor, call your power company asap. Something is NOT right.


Thanks I Have been getting flickering when the fridge kicks in. The lights also go brighter and dimmer randomly.

Hi @DanielC - thanks for sharing.
Do we have permission to view your monitor data? Our Data Science team is very busy right now, but
based on the physical signs you’re seeing (lights flickering, correlation to the fridge turning on) I would recommend reaching out to your utility without further assessment from our end.

We’re extremely interested in knowing what the final verdict is here once your utility is able to inspect the issue further. Details like the ones shared in the report from a user here are very valuable, and we’d appreciate you updating us once you get a final assessment!

Yes do whatever you need to do. I already called the utility and hopefully will get answers.

I will update my situation.

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Unplugged a vending machine.

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WOW, I tried to so some simple plotting but your numbers are wild ! There are a bunch of entries in the data where all 8 Sense measurements are out-of-range at the same second, both min and max, sustained and instantaneous. Usually, you would expect, at max, four to be outside the 110V to 130V range. Here are the list of the time points that have more than 4 measurements out of range in a single second.

Based on the numbers, it looks like Sense samples or assembles Power Quality data once per second. That means sometimes within a 1 second interval, your supply voltage goes from under range to over range. Not sure how you can have both sustained_max and sustained_min for the same leg out of range at the same time, like in the measurement at 2021-09-19 01:11:00

power_quality_raw.csv (78.5 KB)
I forgot to include the data from the above picture, after unpluging a vending machine. I think the spikes that are there are the fridge.

Looking just at the graph it looks like a bad neutral which is an extremely serious condition and one of the leading causes of fires, not to mention electrocution and damaged equipment.

Let the power company know what is going on, let them know you have this data and that you would like to show the technician the logs. That should get them to respond a bit quicker. They are responsible for any damages if the issue is on their end.

Keep us updated to what happens.


Additional Context Photos

ConEd ticket in for bad neutral, high low voltages and flickering.


The unplugged (post 9/19) data looks better.
This shows you the scatter pattern outside of the allowed range for each day.

power_quality_raw (1).csv (78.5 KB)

Today’s data.

Electrician coming tomorrow.

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If I’m reading this right. It looks like a phase shift. Interesting to see what the electrician finds

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That’s not a phase shift. (The phase goes through over 5 million cycles per day, the length of that graph). What you see is a zero-reference shift, the clear sign of a floating neutral. One leg goes up as the other goes down because the midpoint (reference) is shifting.


@demiller9, I agree. A scatter plot of the extremes shows the legs (mostly) moving in opposite direction during spikes, but you can see that in the temporal view as well.

Preliminary report. Is that the panel is not bonded to the ground. a temporary ground was put in place. Voltages are much tighter now.

However a more proper assessment will be done Today or Monday.

Thank you all for your interest and review.


Additional Data. Hopefully the next days data is better with the temporary fix before the bigger fix.


power_quality_raw.csv (78.5 KB)

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Curious what the Sense Labs open neutral detection screen says. This definitely looks like a failing utility neutral connection to me.

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