Help decipher flickering lights and note from power company

[CreekRat]

I need some help deciding if I should call an electrician or the A/C guy first for this problem.

Yesterday my wife noticed the lights were flickering occasionally and immediately assumed the house was about to burn down. I don't enjoy seeing the Mrs fret like this so I went outside where she couldn't keep bothering me only to find that I noticed the light flickering too.

From what I can see flickering only happens when the AC compressor is running so I checked the voltage around the house, then at the mains where they join the fuse box. I found a difference in voltage between the mains and a bigger difference when the A/C is running so I called the power company today to check at the meter.

Listed below are my readings on each main when the A/C is off and running and the notes the POCO left for me when I got home.

I measured voltage on each leg where the mains connect to the panel
AC Off 121.4 - 119.3
AC On 119.5 - 115.6

Fantastic notes left by the POCO:
He changed out all connections from pole to weather head and tightened all lugs inside meter base and tightened the outside main breaker wires.

He measured:
No load and connected but AC not running 122 - 120 - 242

AC off Amps 2 - 1.5
AC on Amps 22.5 25.6

Any thoughts on this? The flickering lights is a new thing so I need to have it checked but I don't know if my first call should be the A/C guy to check the compressor since it's about 15+ years old or an electrician.

 

[pattenp]

You said fuse box. Do actually have a fuse box or circuit breakers? If it is a fuse box pull the mains and re-seat. Check the cartridge fuses for tight connection.

 

[Familyof8kids]

You are in easy range of allowance for almost any type of lighting and no flickering should be caused by your A/C with the data you provided. You could experience a slight dimming when the A/C turns on but no flickering.

We need more data. Is this all lights in the home or one room? If one room what is flickering (example: fluorscent strip in closet, 100 watt screw in lamp, LED alarm clock?

More questions may be asked after you answer these questions above.

 

[CreekRat]

My measurements were at on each let of the main going into the circuit breaker box (breakers, not fuses) .

That's a good question about the flickering, they never actually go off, more like quickly dimming then back up again.

The dimming is only noticeable in a few lights in several rooms. There's no loss of power to any appliance, TV, fan, clocks, etc keep running. When I checked the rooms that I noticed dimming lights the outlets were reading 114-115 volts when the AC was on, other rooms were 119 volts so I guess they are on different legs.

 

[Familyof8kids]

Not to fully dismiss your issue and hard to say not to call anyone but....

If you have any lighting circuits coming from the panel that the A/C is fed from then you will see dimming during A/C start-up with an older A/C system. Especially if incandescent lamps are what you have. Now if you have not noticed this until recently then A/C is having a harder time starting and could be a simple capicator. May not hurt to call an A/C tech that you trust or have a reference from so he does not cause it to fail in 31 days after service. Not saying all are thiefs just my 2 cents.

 

[pattenp]

Are the lights dimming up and down continuously while the A/C is running or do the lights only dim when the A/C first cuts on and then return to their regular brightness?

 

[CreekRat]

Thanks, We've got a decent AC guy I guess, he replaced a capacitor in July and added a charge to the system for not too much money so he was going to be my first call unless someone thought I should have an electrician take a look.

Pattenp, the lights only dim at start-up then brighten back up after a few seconds. They've always done that a little, even when the neighbors AC starts since we share a transformer, but it just seemed to have gotten a lot more noticeable in the last few days.

The lights that are dimming are the incandescent lamps although I did notice the big kitchen fluorescent light dim a little to.

 

[buzz4041]

Sounds like normal inrush currents from the AC system. It will not hurt to shutdown your panel for a few minutes and give all of the connections a tightness check. Be careful at the mains supply as they will still be hot where they come from the meter can.

 

[nehog]

What is the rate of flicker?

I slightly suspect your breaker panel may have a problem--and would suggest that an electrician would be the logical person to check it.

Yes, it could be a problem with the compressor drawing high current on part of the waveform or part of the compression stroke, if the flicker is very fast, but I don't think so... A draw of 22 amps should not cause any changes in voltage.

Also what kind of lights are flickering? Standard incandescent, CFL, regular florescent, or what? That could make a difference.

 

[Andybull]

Check the breaker connections as well as your main line feed. There is a possibility that something is working it's way loose, thus a false connection.

 

[Flash69]

I am not an electrician so take this with a grain of salt.

We had a similar problem to this about 2 years ago. We have an outside panel and an inside (sub) panel. The breaker feeding the inside panel was starting to arc on the bus bar. This caused ALL the lights inside the house to flicker. Turns out the breaker was the cause. The electrician replaced the breaker and the problem was resolved. I don't know if you have a sub panel so this might not apply to you however it's something that could cause this type of problem.

Bottom line is call an electrician to take a look.

 

[matt151617]

I have a similar issue in my house. The lights on all different circuits dim/flicker when lots of loads end up running. Not the standard small dim when a fridge starts, but a constant one. I've watched the voltage drop to 114-112 on a monitor when this happens. Called the power company, they checked everything and assured me it was good. They told me they're obligated to provide voltage within 10% of 120v, so anywhere between 108v and 132v is within tolerance for them. For piece of mind I had an electrician come out and check everything from the meter down, and tighten all the connections, and it was all fine. I've chalked it up to just that's the way the house is. If everything has been checked properly and there's no risk of anything burning down, don't worry about it.

 

[MikeYC]

Sounds like a loose lug connection at the pole if your nieghbor is seeing the same issues. Check for possible oxidation at the connection points also. I have seen Verdigus at a copper Aluminum connection point cause brown outs.

 

[osu69]

About a year after a lightening strike that coursed through my house wiring to ground, my lights started to flicker. Called the power company to remove the seal and found the meter base on my 400 amp service burned to a crisp. Lights flicker for a reason and it is seldom good.

 

[crucible]

Years and years ago I was a cable guy and one day was called to a house complaining of static in their picture. When I got there I had to go to the groundblock (where the arial drop attached itself to the house) and as I was unscrewing the cable line to check it, I could see the lights in the house flickering.

Being a dummy at that moment, I didn't put two and two together and continued unscrew the cable and saw blue sparks(!) and felt a shock go through me, and after I realized I was okay and admonished myself for being a complete *******, I stopped everything and called in the power company as I was then detecting active power on even the wooden pole with my tester.

Turns out the entire pole was electrified as the grounding went bad and it was sending active power to everything connected up to it-cable TV, ground, telephone lines included.

Since you called power here and they give their okay to the outside stuff, I'd now start by looking at your house ground and/or bonding to see if it's electrified with anything else (and check every system connected to it...cable TV, telephone, etc, as they all should be bonded to the house ground somewhere). Beyond that, what others have already said with a loose internal electrical connection, something arcing or otherwise failed electrical element and if you may want to call an electrician to come a take a look-flickering lights are not normal, period.

Whatever you do, be damned careful-even house current can kill.

 

[CreekRat]

Thanks everyone for your input.

I'm going to check the outdoor disconnect for the AC and if there's no issues at that connection I'll have the AC guy back out to check the compressor since it's drawing power so unevenly. If he doesn't find anything and the problem continues I'll have an electrician give everything a once over.

I'll post a follow-up if I get a resolution to the problem.

 

[wyliesdiesels]

Thanks everyone for your input.

I'm going to check the outdoor disconnect for the AC and if there's no issues at that connection I'll have the AC guy back out to check the compressor since it's drawing power so unevenly. If he doesn't find anything and the problem continues I'll have an electrician give everything a once over.

I'll post a follow-up if I get a resolution to the problem.

So, did u figure out anything?