Local line voltage

[maxhifi]

146V is high enough to risk serious damage to anything plugged in, in your house. Floating neutral is the most likely culprit, either on your end or the utility end. I'd suggest to unplug valuable items and fix this problem asap.

[Dave A]

Been watching for a few days and still the same. Seems to be ok during the day around 127vac but climbs after 6pm eastern. About 5vac per hour. 135vac right now and climbing. Power failed two days ago and the genny went on. Smooth 117vac. Back on mains and it resumes. Went to my breakers and dropped one at a time to look for a local issue. No changes. Will pull the panel cover tomm and measure inside. Curiously, my digi meter shows the changes but an analog meter sits at 130vac. Most shut off inside but for window AC units. PECO call on Tuesday.

[old_tv_nut]

Originally Posted by Dave A

... Curiously, my digi meter shows the changes but an analog meter sits at 130vac...

Sounds like it could be a problem with harmonics on the line?

1) Digital meter may be reading peaks instead of RMS
2) An issue could be if electronic gear is responding to these peaks - it would be interesting to attach a DC meter to the B+ in a piece of unregulated gear and see how much that varies during the day
3) Be prepared to show/tell the power co. what kind(s) of meter(s) you are using

[Dave A]

Wayne may have it. The house connected items are visually stable. No flickers, sudden bright bulbs, window AC's choking, etc. I only noticed it after my 21CT55 was acting up on the line connection. On a variac it calmed down but I diagnosed a faulty RF modulator for that problem. A variac analog meter did show some excess on the line side. On the regulated side it was fine at 115vac. But what causes peak voltage to float up and down? Beyond my basic AC knowledge.

[maxhifi]

Measure across the two hots in your panel, and see if the 230V varies proportionally to the increase you're reading at the outlet. If it does that rules out the neutral as an issue.

It is entirely possible this is bad utility regulation, where the voltage rises excessively as AC units shut off for the night.

[Mi40793]

Power companies use ‘tap changers’ on long medium voltage lines to keep the day/night voltage within range. These are auto-transformers that adjust themselves, used in groups of three on medium voltage (13.8kv) lines. Capacitor banks are used to correct power factor. Similar to supplying DC in old cities, up to 1999 a power plant was supplying 25 cycle AC to mines and factories in SW Missouri and NE Okla, legacy from installations ~1910. I think Pennsylvania has railroads still operating on 25 cycle AC. There was a lot of 25 in early days, including Niagra falls.

[zenith2134]

Rockaway Beach, NY used to have dips down around 89VAC in hot summer months. Overhead lines and an old, poorly maintained system.
Hurricane Sandy in 2012 changed that. New utility, massive overhauls. Plus most customers had to install a new panel since it was underwater.

We now have a year-round constant 119-122 VAC. No smartmeters here either for now. Opted out.

[Colly0410]

When I went to Malta in 1991 the line voltage was all over the place. It's supposed to be 240 volts, but the lights brightness would be up & down like a yo-yo, the CRT TV's picture would shrink & lose frame lock at random, I didn't have a volt meter with me so don't know what the actual voltage was... Went again in 1997 & took my volt meter & the voltage was rock steady at 240 with just a couple of volts either side. Think there must have been an upgrade since my first visit...

[ARC Tech-109]

I live in a small town that is 2400/4160v primary and have not seen the voltage issues that others are experiencing, I show 118V despite being on the same 69kv/4160v substation transformer as the nearby large plastics plant. Neighborhoods are dotted with the old black oval & round side bushing transformers fed with either hard drawn or stranded copper with many of the houses using exposed hard copper drops. I'm a lead at the plastics plant and run the 1000-ton presses, Springfield-1000 takes 1200A/phase at 480V with the extruder heaters taking over half that. The plant 4160 primary is fed by several runs of 5KMCM and secondary is 4 bus runs at 2500A/480Y for the large products area. The electric bill is over $100K/week.
I did measure my outlet voltage over the thanksgiving weekend as the plant was "cold" and it was running 118.9V on my Fluke 8010A

As antiquated as my local local power system is I have to wonder why others are having so many issues with high line voltages, 130V would be the upper limit. The internal power transformer of say a CTC-25 could withstand 150V on the primary but the horizontal output might not as this could introduce a runaway condition possibly arcing over the flyback or pushing the 6JE6 beyond its safe dissipation.
I have a T940 Magnavox with the NORM/HIGH line switch, clearly this was a concern back in the late 60's. Running I find +420V going into the filter choke and about 5.9-6.2V on the heater fuse to ground, normal but a rise to 130+ primary would push this to almost 7V and over 460V on the B+. Clearly makes a good argument for a 500VA Sola transformer as I doubt the utility is going to address anything below 140V calling it an isolated incident.