Service drop wire size

[Taylorjm]

So, in a house we bought, it was built in 1995 and has a 150 amp service. So everything is somewhat still up to date. It's a single story ranch with a walkout lower level. We had central ac and ductwork added, since it has boiler heat. It's a 3 ton unit, nothing outrageous. All the lights in the home are led. We are finding when certain appliances turn on, we get some lights dimming for a second. If the a/c, well, microwave or garbage disposal turn on some lights in the house will dim for a second. We have gas stove and dryer, so not very many hungry appliances at all. The well and a/c are 220v and the microwave and garbage disposal are both on their own circuits, and the lights are on other circuits. So it's not an issue of the lights being on the same circuit, or even on the same leg since the a/c and well are on both legs. The only other thing I noticed is the service drop from the poco seems a lot smaller wire than the 2/0 aluminum that runs from the service head, to the meter and to the breaker box. I know the service drops can be smaller, but even if it was copper, seems like it's nowhere close to being able to handle 150 amp service. What do you think?

 

[WorthFlorida]

LED light output does not change with slight variances of input voltage but it is possible that dimmable LED's units might but I doubt it. It's not like an incandescent. I would call the power company and ask them to check the connections at the mask. We did have a post a few years ago and the problem was one of the lines had heavy corrosion at the splice. I'm suspecting the neutral might be the problem since you're drawing nowhere a heavy load. Somewhere near the meter there will be one or two ground rods, most will have one ground rod. Besure the connections are good at the ground rod. Another thing you can do is cycle all of the circuit breakers off and on a few times including the main 150 amp breaker. This can wipe clean any dirty contact inside the breaker that might have some oxidation built up over the years. Home inspectors will usually do this for their report.

From a google search. A electric voltage drop is not the same as a waveform change that LEDS are designed for dimming.
Dimmer Switches work by reducing the power delivered to your light bulb. They do this by trimming a section of a waveform, either on the leading edge or trailing edge of the wave. Manufacturers have designed their LED light bulbs to be compatible with the majority of common 'trailing edge' household dimmers.

I purchased my current home in 2011 that was built in 2007. I had something similar where the lights would dim for a second but it wasn't related to anything turning on, at least from what I noticed but maybe the AC. When the problem cleared I do not know when it happened since we were living in the home full time. What did happen was the smart meter was changed out without my knowledge until I noticed it was mentioned on the electric bill. Since we didn't live in the home but for a few days a month, the electric usage was very small and the power company any have reasoned to believed that the smart meter was out of calibration. We moved in full time Dec 2016 and it was in the back if my mind to have my electrician friend check the it out but I noticed it was no longer happening.

 

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[Taylorjm]

LED light output does not change with slight variances of input voltage but it is possible that dimmable LED's units might but I doubt it. It's not like an incandescent. I would call the power company and ask them to check the connections at the mask.

Thanks for the suggestions. The led bulbs we have are not dimmable and we definitely notice it happening when the listed appliances start up. I would agree that it's possible there's a bad connection on the meter or poco side because it shouldn't have to do with power loss somewhere since it's something as small as the microwave turning on. I agree that it could also be related to the led bulbs being sensitive when compared to incandescent bulbs.

 

[Stuff]

You can check for loose connections in the feed to your panel but sounds like you need to bring out an electrician. They can then pull in the POCO as needed.

 

[WorthFlorida]

You cannot tell if the drop wire is smaller. It might just be thinner insulation. It is doubtful that it is copper wire but copper can be a smaller gauge by one size for the same current rating as aluminum.

 

[Reach4]

I don't know if you are comfortable taking the front panel of the breaker box off.
I would monitor the voltage between each hot and neutral as you have somebody turn the disposal on and off.

What is the max and min voltage you see?
Does the voltage go up on one hot, and down on the other, when you turn the disposal on? I would expect that and I would expect the effect to be bigger if the wires are more undersized.

 

[Taylorjm]

I don't know if you are comfortable taking the front panel of the breaker box off.
I would monitor the voltage between each hot and neutral as you have somebody turn the disposal on and off.

What is the max and min voltage you see?
Does the voltage go up on one hot, and down on the other, when you turn the disposal on? I would expect that and I would expect the effect to be bigger if the wires are more undersized.

Pulling the panel and checking the voltage isn't a problem, I can give that a try next time I'm at the house. What about tandem breakers? There are 36 circuits in a 30 space box so they have several tandem breakers for many of the circuits. I wouldn't think it would make a difference, but I'm not sure.

 

[Taylorjm]

You cannot tell if the drop wire is smaller. It might just be thinner insulation. It is doubtful that it is copper wire but copper can be a smaller gauge by one size for the same current rating as aluminum.

Yes, it could be thinner insulation, but it's also out in the open air, so it can supposedly handle higher amperage with smaller wire, and I also doubt it's copper, but it sure looks a lot thinner than the 2/0 that's in the service head. Now, I highly doubt I would need 150 amps, ever, probably lucky to need half that at any given time.

 

[Reach4]

Pulling the panel and checking the voltage isn't a problem, I can give that a try next time I'm at the house. What about tandem breakers? There are 36 circuits in a 30 space box so they have several tandem breakers for many of the circuits. I wouldn't think it would make a difference, but I'm not sure.

If the question is about the light-dimming thing, if the voltages from each hot to lug stays pretty consistent during light dimming episodes, then you can think about things downstream of the main lugs coming in.

I cannot think of a way that using tandem breakers would cause this unless the lights are on the same breaker as the garbage disposal. Unlikely.

If you were asking if using tandem breakers in your box is permitted, I wouldn't know. But I don't think that is causing your dimming.

 

[Taylorjm]

If the question is about the light-dimming thing, if the voltages from each hot to lug stays pretty consistent during light dimming episodes, then you can think about things downstream of the main lugs coming in.

I cannot think of a way that using tandem breakers would cause this unless the lights are on the same breaker as the garbage disposal. Unlikely.

If you were asking if using tandem breakers in your box is permitted, I wouldn't know. But I don't think that is causing your dimming.

I was still asking about the light dimming thing, so I will check the voltages. I wouldn't think tandem could cause an issue either, and I wasn't asking if they are allowed, I know by the diagram which circuits they are allowed in my box. I think I'm going to look at upgrading the panel to a 200amp 40/80 space and eliminate most of the tandem breakers. We will be remodeling the kitchen and going with an induction range, so I'm going to need a few open spaces for some new circuits anyway and if I need to use tandem breakers, they can be used in any spot on the newer boxes. Then I'll see if the light dimming continues after swapping out the panels and reinstalling new breakers. Maybe there's a loose wire somewhere.

 

[Reach4]

I think I'm going to look at upgrading the panel to a 200amp 40/80 space and eliminate most of the tandem breakers. We will be remodeling the kitchen and going with an induction range, so I'm going to need a few open spaces for some new circuits anyway and if I need to use tandem breakers, they can be used in any spot on the newer boxes. Then I'll see if the light dimming continues after swapping out the panels and reinstalling new breakers. Maybe there's a loose wire somewhere.

In your case, the symptoms seem pretty consistent rather than intermittent. So your thought about the feed lines being undersized may indeed be the problem.

Another way to get more spaces is to put a 60 or 100 amp pole breaker in the existing box, and feeding a subpanel, which could be by the new kitchen.

You may have a better chance to get the electric company to upgrade your feeders by switching to the 200 amp box. I don't know how those negotiations go. Present your data to them if it supports your theory, and they might upgrade the lines anyway.

 

[Taylorjm]

In your case, the symptoms seem pretty consistent rather than intermittent. So your thought about the feed lines being undersized may indeed be the problem.

Another way to get more spaces is to put a 60 or 100 amp pole breaker in the existing box, and feeding a subpanel, which could be by the new kitchen.

You may have a better chance to get the electric company to upgrade your feeders by switching to the 200 amp box. I don't know how those negotiations go. Present your data to them if it supports your theory, and they might upgrade the lines anyway.

I thought about a subpanel, but the current box is a GE powerline and I really don't like the way things are laid out with regards to the neutral bar and a lack of spaces for some reason. There are other subpanels in the home, one in the attached garage, one in a separate garage and another to feed the a/c air handler and outside unit and they are all square D Homeline boxes, so I'm going to get rid of this GE box and go with a homeline like the rest of the home. It will give me a chance to clean out this overloaded GE box and organize the wires. Once I swap the panel and get it inspected, I'll ask the inspector what he things about the feed wires to the service head and see if he has any insight. If it is indeed undersized and causing a problem, I don't believe the poco around here would charge to upgrade the line, especially if I can prove that they undersized it in the first place. It would be an easy swap for them since the transformer is on the pole going direct to my home, no trees or anything to make it difficult to upgrade. Usually around here I've heard they will upgrade the line without charge since you will be using more electricity.

 

[WorthFlorida]

I'm not sure where the tandem breakers started, but upgrading to 200 amp service will probably take a new drop wire. The utility company may bill you for the increased size drop wire. Check with your utility company how to go about the upgrade. All will require a permit and most may require a license electrician to pull the permit and pass inspection before changing over the service. The local jurisdiction may require to change most breakers to AFCI (current code) and just about all circuits now require GFCI. It may not just be a panel upgrade.

 

[JerryR]

Some LEDs are more susceptible to voltage changes and some aren’t.

We have been fighting a fast flickering problem that occurs over 5 seconds exactly every hour at 10 minutes after the hour for over a year at our Florida cabin. It only shows up only on certain LED bulbs. I have confirmed it does exactly the same thing at exactly the same time at at least 4 other homes in the community some as far as 1/2 a mile away only on LED bulbs.

The local power company, FP&L, has come out and put voltage monitors on several homes and were unable to capture any fluctuation. They even assigned an engineer. To try to identify the issue.
They replaced transformers, LA (lightening arrestors) and some suspect lines with no changes is flickering. Then recently for no known reasoned the flickering has totally disappeared.

My point is that the flickering was only visible on certain LED bulbs which seem to be susceptible to voltage fluctuations.

 

[Taylorjm]

I noticed something else that may or may not be related to this issue. The transformer for the home is 10 kva, which translates to 42 amps at 220v. Sure doesn't sound like much once once you get two refrigerators, a 10 amp filter pump, 3 ton a/c and then the occasional well pump or garbage disposal can trigger a flicker. What do you think? I haven't even tried firing up the welding machine to see what happens. I know from the mast down to the breaker box is all rated to handle 150 amps, and I know I'll never need that, but only being able to supply 42 amps seems pretty low. The house was built new in 1995, and there wasn't an existing structure on the property, so the electrical service was new for the home and should have been setup to supply the 150 amp service.

 

[Reach4]

The transformer for the home is 10 kva, which translates to 42 amps at 220v.

Good point.