Brownout or ?

This morning noticed lights flickering.  I wasn't paying much attention until wife brought it up.
 
Looking at the UPS status noticed that the power changes has been triggering UPS changes. (checked three UPS's connected to three monitoring programs).
 
Decided to plug in a digital VOM to the outlet.    Watching seeing voltage is steady at 121.7 - 121.8 AC except when lights are flickering (been pretty steady on and off every few minutes).  When the lights are flickering AC voltage is dropping down to 118-119 AC.
 
As a test of sorts shut off the HVAC and watching AC voltage via VOM.
 
Voltage went up a bit to between 122.1 to 122.3 steady with an occasional drop to around 121.1 - no lights are flickering.
 
Turned AC on again after about 15 minutes.  Initial start flickered the lights and voltage dropped to 118 and went back to 121.5-121.8.  Saw again lights flickering once.  Noticed again a rise in the average voltage to to 122.1-122.5
 
Looking / listening outside AC compressor seems to be running fine and not shutting off and on or making noise.
 
Is this a brownout?
 
Googling bit a brownout typically is longer than a second or two so wondering what it is I am seeing here.

I wouldn't call it a brown-out with those voltage readings. I think that anything above about 110vac is acceptable in a residential service. Is it all lights or just one fixture? I would try turning on lights in different rooms and see how they look.
 
Mike.

Was reading that the official average is around 117 VAC. 

I then went to my office for a bit and noticed same flickering with my desk lamp.
 
Just now glanced again at the VOM and now the voltage is above 123VAC and going up to 126VAC.  (averaging now around 125vac).  Never really pay attention to this stuff.
 
 
Lights flickering again but this time with a decrease to 122.9 VAC.

If you are comfortable working inside the load center then I would check voltage on each line coming into the house there next. Your voltages are higher than I would expect and I can't think of any wiring problem that would cause voltages to go that high. If the voltage is above 120 volts at the load center and fluctuating then I would call the electric supplier and make them aware of it.
 
Mike.
 
EDIT
 
If you test the voltage at the load center try it with the main breaker both on and off. If the voltage fluctuates with the main breaker off  then I would think that the problem is outside your house. If the voltage fluctuates only when the main is on then I would trip one breaker at a time to see if any eliminate the problem.

A large load that is quickly coming and going would cause the voltage to fluctuate like that. You might try going around the house turning things off to find the cause. Look at the large loads like an electric water heater, well pump or as you said air conditioner?
 
Mike.

Thank you Mike.
 
Yeah here have a new outside compressor (well a couple of years old) and did have to replace a bulging supercap on it year after it was installed.  With that I also installed a separate surge protector outside just for the AC compressor.  Wondering.  When the supercap went out my AC compressor also went out with no warning. 

In many cities they use a thing called Network voltages. This is also know by other names such as
 
3 phase 3 wire wye, or
3 phase 4 wire, one leg out.
 
They give you two out of three phases on a three phase system. Each unit or floor may get two different phases on a rotational basis to distribute loads.
 
Instead of the old 120//208 volts they compromise between the 120 and 240 volt connection voltages by increasing the voltages.
 
They aim for 125/216 volts so the 240 loads don't run too low and the 120 volt loads do not run too high.
These are all well within the North American voltage specs.
 
120 or 240 vac +/-10%
 
There never was any 110vac, 115vac or 117vac spec. That was all dreamed up by equipment manufacturers as they thought there would be voltage drops in wiring.

pete_c said:

Thank you Mike.
 
Yeah here have a new outside compressor (well a couple of years old) and did have to replace a bulging supercap on it year after it was installed.  With that I also installed a separate surge protector outside just for the AC compressor.  Wondering.  When the supercap went out my AC compressor also went out with no warning. 

Click to expand...

 
My air conditioner died due to a failed capacitor years ago. I replaced the cap and the same thing happened the following year. At that point I did a little research and found what they called a start-up kit for the unit. If I recall it was an additional capacitor  and I don't remember what if anything else. It was intended to smooth out the surge that occurs at startup and there hasn't been a problem in many years now.
 
Mike.

LarrylLix said:

In many cities they use a thing called Network voltages. This is also know by other names such as
 
3 phase 3 wire wye, or
3 phase 4 wire, one leg out.
 
They give you two out of three phases on a three phase system. Each unit or floor may get two different phases on a rotational basis to distribute loads.
 
Instead of the old 120//208 volts they compromise between the 120 and 240 volt connection voltages by increasing the voltages.
 
They aim for 125/216 volts so the 240 loads don't run too low and the 120 volt loads do not run too high.
These are all well within the North American voltage specs.
 
120 or 240 vac +/-10%
 
There never was any 110vac, 115vac or 117vac spec. That was all dreamed up by equipment manufacturers as they thought there would be voltage drops in wiring.

Click to expand...

 
Interesting. Is this type of service prone to the voltage bouncing and causing lights to flicker?

Are the flickering lights fluorescent?  I ask this because at least the old style magnetic ballast fluorescent blubs/fixtures tend to be more voltage sensitive.

Thank you ecborgoyn.   Just moved to the basement workshop (tinkering a bit this morning) and have my large circular with magnifying glass florescent lamp on and the basement lighting is 100% CCFL.   No basement lighting is flickering here right now.   One of the features of the the installed outside surge protector is that it is supposed to protect the starter capacitor on the outside compressor.  First time I ever saw a metal cap that large with a bulge on it.
 
It was a pita to install as I had to rewire all of the outside compressor HV electric.  Thinking I did post a little pictorial of my endeavor.
 

Went outside again.  This time the compressor was off and didn't go on after I cranked the thermostat down a bit. 
 
So it appears now again maybe to be a supercap issue.   Wife likes the laundry room cold (frigid cold) and noticed that it is not cold this morning. 
 
Didn't remove the cover to do a visual and just assuming right now that this is the problem.  

Went outside with tablet and turned on AC cool while watching / listening to outside HVAC compressor.  Immediately heard a loud buzz and clicking sound on the outside AC and compressor was not going on.
 
Called old HVAC friend (retired).  Said that a supercap can be a problem again.  So it will be fixed today which is a good thing.

I was just doing some reading and it was suggested that lack of maintenance can cause the cap to overheat and bulge. It is recommended to clean the coils in the outside unit because when they get dirty the motor works harder and causes undue stress on the capacitor and the electric motor.
 
I think that I will take the cover off of mine and have a look at it.

Thank you Mike.  I asked too if a new supercap can go in a year or two and was told it can.
 
Yea here did the spring clean up of the coils which I do typically twice here (spring and fall).  I also do a furnace filter change every month here.  (well electronic filters).
 
Fixing this afternoon.
 
Just an FYI relating to price.
 
Picking up the capacitor using friend's account it is $55.  Looks to be a 5 minute job.
 
Replacing capacitor and checking compressor (with guages) is $100 plus $55 for the capacitor.  He will clean the coils again while checking it.
 
I want to have it checked with gauges so went with service call such that total is $155 which I think is fair.  Last time though it was a freebee from friend.