Wanted to post an example of what my home’s utility voltage looks like this time of year with hot weather and a lot of AC use. You’ll see that as soon as things begin to heat up for the day, the voltage begins to sag. Things come back up to the high end of the range in the evening. You can see instantaneous dips throughout the day as my AC starts up.
Locally, I share a 50 or 75 kVA (I forget) distribution transformer with at least 5 other houses, some of which are large 10k+ sf houses. I’m attached to a 12.8kV distribution feeder without any voltage regulators. This feeder and one other locally is supplied by a small substation 1-2 miles away (cable distance) with a single transformer fed from BGE’s 33kV subtransmission network, so there could be a tap changer there, but I don’t see any evidence of one operating on the voltage graph.
The only time I notice any voltage effects is when my AC starts up locally, and I can see a flicker in some of my lights.
Looking at this a little closer, it looks like we may have up to 10 houses on the puny little pole pig feeding my house. It’s on the next pole behind the cap bank here:
Half of those houses are over 10ksf, at least two have pools, and we don’t have natural gas service, so lots of heat pumps. Surprised we havent cooked that transformer yet!
Just noticed that new lab chart today and also found it interesting. My spike count is much higher but I also have a larger household demand with pool equipment, 2 AC units (3 & 2 ton) plus the entire house runs on electric items. Dips to 108V and recorded 52x
I checked mine a few days ago and no issues.
I checked today and lots of issues. We had a heatwave yesterday and some local feeder issues, that have since been resolved.
Interesting… I have a 3 and 4 ton AC unit, plus two EVs, one that charges at 80A and I still don’t have any spike/dip alerts. But charging at 80A does drop my baseline voltage by about 2V.
Over the years I had both an Electrician and HVAC person out and they found no issues. Presented Sense data and got a reaction “wow, you use a lot of power” but still no solution. I have a 38 panel solar/telsa battery project starting later this summer. The local provider (Eversource) already informed me they have to replace the lines to the house. Let’s see what it looks like after this is all done. Today the house peaked at 17000 with the 2000/6000 spikes every 30-50 min depending on HVAC calls.
Hey @john.desharnais. We’d love you to post a separate post with your information to Sense Labs! Examples of users Power Quality helps provide context for folks who are looking for information.
@jonhawkes, wow. That’s a really interesting screen capture of a sustained low voltage event (day) on your feeder! Very cool. Thank you for sharing that. Has your electrical utility announced what the root cause local feeder issue was?
Just noticed the Power Quality alert notifying me that I have have encountered a number of voltage dips or spikes. I did not notice any power interruptions. We are running our AC due to the hot weather. Trends attached. I’m not sure what to do next other than monitor periods when I’m using my HVAC. Could also be supply in the area as other users are using their HVAC units.
@dmelideo, the daily sag cycle is probably due to heavy AC usage as well as general daily usage in your area, the short dips due to your AC kicking in.
