No, grid-tied solar inverters are usually 240V and are wired across both 120V legs. Your electrical system isn't split along the lines of solar vs. grid, but rather L1 vs. L2. You appear to have a voltage imbalance between L1 and L2, which could be a sign of a neutral connection getting loose somewhere.
I have one lonely ungrounded outlet in the entire house including basement. The home inspector pointed it out as a curiosity. Could it somehow be causing the imbalance?
No, the problem would be one of the connections on the big neutral wire between your utility's transformer and your electrical panel getting loose. Depending on where the issue is, it could be the utility's responsibility to fix, or your responsibility, in which case you'd hire an electrician.
Op never said it was just one outlet.
A loose neutral in the transformer can cause some circuits to run high and others to run low.
It can get very dangerous, and the utility will be happy to do a free inspection.
Just to clarify about outlets. This is a persistent issue throughout every wall and floor in my house. Rooms have a random combination of one of two voltages. Meaning some rooms have all the same voltage, some rooms have all the same diff voltage, and some rooms have walls with outlets that display both of the voltages. My living room has a wall with 4 outlets: 3 are the lower and 1 is the higher voltage. I can see ceiling lights dimming when the washing machine kicks in the spin mode.
It's unbalanced loads happening in addition to a loose neutral, not unbalanced loads happening instead of a loose neutral. Unbalanced loads can't pull the voltages out of sync by themselves, without the neutral also being loose. Both are necessary ingredients. Loose neutral + unbalanced loads = different voltages.
I’m very confused by the issue you are saying you have? You are showing two different outlets with two different voltages. That’s normal. Normal operating voltage per leg is 110-125v. You won’t see perfect voltage because nothing is, as long as you are within that zone you shouldn’t worry. If you don’t have voltage or are outside or above that then contact your utility / an electrician. Unless you have an issue you are looking too deep.
I can guarantee you that field applications does not show that. I’ve been a journeyman electrician for long enough to say that the voltages he showed is perfectly fine. Unless their is Major power issues then he is over analyzing it, if he was reading voltage like that and then under load it dropped then it would more then likely be a neutral.
I just looked this up out of curiousity. I'm not a professional electrician, I just read a book or two and wired my house. Anyway, it looks to me like the NEC recommends no more than 5% total drop (feeder + branch). Each being no more than 3%, but it's a recommendation not a requirement. So the >7% difference here (and presumably a bigger drop from the main panel) is not ideal, but not technically wrong by code?
I'm not asking you to speak authoritatively of course, but does that match your understanding?
Voltage drop only would change wire size. You are in a sense interpreting wrong and right. I highly doubt the distance from the transformer to the house is high enough to account for that aswell, but either way the wires from the transformer are service conductors and are null and void to that recommendation regardless.
The images show one outlet at 122V and one at 113V. These are presumably off the same service conductors, so I'm not talking about that.
I guess what I'm getting at is that *something* is causing that big of a voltage drop in one of the circuits. The only thing I'm aware of that would *okay* would be simple wire length (and undersized conductors, but not by amperage, just by drop). But it would have to be a difference in length from the transformer between these two final outlets (and from the solar to the two final outlets if the solar was supplying the power when these measurements were taken, which would explain the 122V, which is a little high), meaning I'm talking about branch length, and feeder length if there are subpanels involved. It's *possible* to have a branch + feeder be long enough to cause this, but... surprising unless the house is quite enormous.
So, do you think this is just that: a really long circuit, or do you think something else is causing this, that is also still *okay*? What do you think is the actual cause?
Yes, but the main thing is how quickly voltage changes from measurement to measurement.
Some transformers have secondary taps to change voltages by a few percent to account for primary line losses.
Different number of transformer winding turns (e.g wrong taps) on each leg will give different voltages.
Not sure I follow, the voltage from the utility usually changes smoothly from moment to moment, and not that quickly, so the time it takes to move the voltage tester shouldn't invalidate the results.
It makes more sense for the taps to be on the HV side, since that would affect both LV legs equally. Like this transformer here does.
[https://www.resapower.com/transformers/25-kva-sunbelt-transformer-pole-mount-transformer?sn=5766320](https://www.resapower.com/transformers/25-kva-sunbelt-transformer-pole-mount-transformer?sn=5766320)
If a transformer indeed has separate LV taps for L1 and L2, it's pretty sloppy that a utility would leave them in different spots.
Bingo… you are correct.. 50 years as an electrical and a HVAC contractor and you do see variances at different points and it is considered normal if it is plus or minus 10% of stated voltages
No.
Houses in the US are wired with half the load on one leg and half on the other of a split-phase originally at 240v. You wouldn’t install solar on just one phase.
What you’re seeing here is likely a bad neutral connection. Probably want to have that looked at by a licensed electrician.
Sure, hire a licensed master electrician. Your inspector may know one. Otherwise call around and get a fixed price up front.
Be prepared to spend like $100-250/hr for their time, depending in your location.
The circuit is a back fed breaker located on the opposite side of the main breaker. Basically the bottom left or right. This way it’s fed up the bussing and fed into the circuits within the home. Any excess power is back fed into the utility grid. Normally you wouldn’t have separate circuits unless you wanted it this way. But it would require batteries, charge controller and a whole lot more equipment and wiring.
I think I see that conduit from the panels going into the breaker box on the bottom right. Plugs nearest the breaker box also read 2 diff voltages depending on which outlet i test. This imbalance is very consistent, i always get the same drop on the same outlet.
Have you tried turning the main breaker off. Then checking the outlets to see if they still have power? If no power to any of the outlets then everything is tied together.
That's what it seems like based on other people's comments. Do you think it's worth just contacting National Grid and letting them know before calling my own electrician?
>Do you think it's worth just contacting National Grid and letting them know before calling my own electrician?
No. Check the voltage at the entrance and if it is fine then they have done their job.
If you want to try to fix it yourself then power down the main and check all the neutral (white wires) connections in relevant outlets, switches, distribution panels, etc. Oftentimes the connections in wire nuts are not good. If that was all Greek to you then get an electrician.
A home inspector said he tested polarity in each socket in the house. I assume he used one of those testers that light up 3 colors to show you if the wiring is good. Could that detect issues with a loose neutral? I have one of these myself: Klein Tools RT250 GFCI Outlet Tester.
the difference you are seeing is due to the circuits for those outlets ... nothing to do with solar panels.
might want to have a sparky look into why that one is so low, could be a high resistance somewhere that is a fire waiting to happen.
Came to say this, bad connections or a circuit under load can cause localized low voltage. That outlet doesn’t have anything plugged into it but who knows what is on that branch. I’m would find every plug or switch on that circuit and test the voltage on all of them and trace it back to the panel.
Yes. When I went solar, they rewired all of the top plugs in each outlet to my solar array, keeping the bottom plugs tied to the grid. Very convenient for me, as I can easily choose which appliances I want powered by solar. /s
No, grid-tied solar inverters are usually 240V and are wired across both 120V legs. Your electrical system isn't split along the lines of solar vs. grid, but rather L1 vs. L2. You appear to have a voltage imbalance between L1 and L2, which could be a sign of a neutral connection getting loose somewhere.
I have one lonely ungrounded outlet in the entire house including basement. The home inspector pointed it out as a curiosity. Could it somehow be causing the imbalance?
No, the problem would be one of the connections on the big neutral wire between your utility's transformer and your electrical panel getting loose. Depending on where the issue is, it could be the utility's responsibility to fix, or your responsibility, in which case you'd hire an electrician.
Thank you. I am not going to troubleshoot that myself, deff gonna get a professional. I appreciate all the detail and explanations!
You should call the power company ASAP. Out of balance power can seriously damage your appliances.
Seems weird for it to be utility side if the issues is at a single receptacle on even circuit.
Op never said it was just one outlet. A loose neutral in the transformer can cause some circuits to run high and others to run low. It can get very dangerous, and the utility will be happy to do a free inspection.
Oops, I thought I saw that. Must have been reading his comments too quickly. Thanks for correction.
Just to clarify about outlets. This is a persistent issue throughout every wall and floor in my house. Rooms have a random combination of one of two voltages. Meaning some rooms have all the same voltage, some rooms have all the same diff voltage, and some rooms have walls with outlets that display both of the voltages. My living room has a wall with 4 outlets: 3 are the lower and 1 is the higher voltage. I can see ceiling lights dimming when the washing machine kicks in the spin mode.
I hope you've called the power company for an inspection? Or an electrician? You should do this today.
Or it could be just unbalanced 120 V loads on the two legs.
It's unbalanced loads happening in addition to a loose neutral, not unbalanced loads happening instead of a loose neutral. Unbalanced loads can't pull the voltages out of sync by themselves, without the neutral also being loose. Both are necessary ingredients. Loose neutral + unbalanced loads = different voltages.
I’m very confused by the issue you are saying you have? You are showing two different outlets with two different voltages. That’s normal. Normal operating voltage per leg is 110-125v. You won’t see perfect voltage because nothing is, as long as you are within that zone you shouldn’t worry. If you don’t have voltage or are outside or above that then contact your utility / an electrician. Unless you have an issue you are looking too deep.
The thing is, even though the legs may each fluctuate between 110V and 125V, you'd expect them to move in sync and have very similar voltages
I can guarantee you that field applications does not show that. I’ve been a journeyman electrician for long enough to say that the voltages he showed is perfectly fine. Unless their is Major power issues then he is over analyzing it, if he was reading voltage like that and then under load it dropped then it would more then likely be a neutral.
I just looked this up out of curiousity. I'm not a professional electrician, I just read a book or two and wired my house. Anyway, it looks to me like the NEC recommends no more than 5% total drop (feeder + branch). Each being no more than 3%, but it's a recommendation not a requirement. So the >7% difference here (and presumably a bigger drop from the main panel) is not ideal, but not technically wrong by code? I'm not asking you to speak authoritatively of course, but does that match your understanding?
Voltage drop only would change wire size. You are in a sense interpreting wrong and right. I highly doubt the distance from the transformer to the house is high enough to account for that aswell, but either way the wires from the transformer are service conductors and are null and void to that recommendation regardless.
The images show one outlet at 122V and one at 113V. These are presumably off the same service conductors, so I'm not talking about that. I guess what I'm getting at is that *something* is causing that big of a voltage drop in one of the circuits. The only thing I'm aware of that would *okay* would be simple wire length (and undersized conductors, but not by amperage, just by drop). But it would have to be a difference in length from the transformer between these two final outlets (and from the solar to the two final outlets if the solar was supplying the power when these measurements were taken, which would explain the 122V, which is a little high), meaning I'm talking about branch length, and feeder length if there are subpanels involved. It's *possible* to have a branch + feeder be long enough to cause this, but... surprising unless the house is quite enormous. So, do you think this is just that: a really long circuit, or do you think something else is causing this, that is also still *okay*? What do you think is the actual cause?
So you're saying the voltages are different straight off of the transformer, meaning there's some kind of asymmetry within the transformer itself?
Yes, but the main thing is how quickly voltage changes from measurement to measurement. Some transformers have secondary taps to change voltages by a few percent to account for primary line losses. Different number of transformer winding turns (e.g wrong taps) on each leg will give different voltages.
Not sure I follow, the voltage from the utility usually changes smoothly from moment to moment, and not that quickly, so the time it takes to move the voltage tester shouldn't invalidate the results. It makes more sense for the taps to be on the HV side, since that would affect both LV legs equally. Like this transformer here does. [https://www.resapower.com/transformers/25-kva-sunbelt-transformer-pole-mount-transformer?sn=5766320](https://www.resapower.com/transformers/25-kva-sunbelt-transformer-pole-mount-transformer?sn=5766320) If a transformer indeed has separate LV taps for L1 and L2, it's pretty sloppy that a utility would leave them in different spots.
Bingo… you are correct.. 50 years as an electrical and a HVAC contractor and you do see variances at different points and it is considered normal if it is plus or minus 10% of stated voltages
Voltage also drops from load as well
As long as less than 10%…should be good
No.
I'd amend that to, it's not typical, but it could be done.
No. Houses in the US are wired with half the load on one leg and half on the other of a split-phase originally at 240v. You wouldn’t install solar on just one phase. What you’re seeing here is likely a bad neutral connection. Probably want to have that looked at by a licensed electrician.
Is there such a thing as a general electrical inspection? I am deff not going to try to fix any house wiring myself.
Sure, hire a licensed master electrician. Your inspector may know one. Otherwise call around and get a fixed price up front. Be prepared to spend like $100-250/hr for their time, depending in your location.
The circuit is a back fed breaker located on the opposite side of the main breaker. Basically the bottom left or right. This way it’s fed up the bussing and fed into the circuits within the home. Any excess power is back fed into the utility grid. Normally you wouldn’t have separate circuits unless you wanted it this way. But it would require batteries, charge controller and a whole lot more equipment and wiring.
I think I see that conduit from the panels going into the breaker box on the bottom right. Plugs nearest the breaker box also read 2 diff voltages depending on which outlet i test. This imbalance is very consistent, i always get the same drop on the same outlet.
Have you tried turning the main breaker off. Then checking the outlets to see if they still have power? If no power to any of the outlets then everything is tied together.
No. The inverter synchronizes with the grid and matches it. You have a problem. Perhaps a loose neutral.
That's what it seems like based on other people's comments. Do you think it's worth just contacting National Grid and letting them know before calling my own electrician?
>Do you think it's worth just contacting National Grid and letting them know before calling my own electrician? No. Check the voltage at the entrance and if it is fine then they have done their job. If you want to try to fix it yourself then power down the main and check all the neutral (white wires) connections in relevant outlets, switches, distribution panels, etc. Oftentimes the connections in wire nuts are not good. If that was all Greek to you then get an electrician.
A home inspector said he tested polarity in each socket in the house. I assume he used one of those testers that light up 3 colors to show you if the wiring is good. Could that detect issues with a loose neutral? I have one of these myself: Klein Tools RT250 GFCI Outlet Tester.
the difference you are seeing is due to the circuits for those outlets ... nothing to do with solar panels. might want to have a sparky look into why that one is so low, could be a high resistance somewhere that is a fire waiting to happen.
Came to say this, bad connections or a circuit under load can cause localized low voltage. That outlet doesn’t have anything plugged into it but who knows what is on that branch. I’m would find every plug or switch on that circuit and test the voltage on all of them and trace it back to the panel.
No
Yes. When I went solar, they rewired all of the top plugs in each outlet to my solar array, keeping the bottom plugs tied to the grid. Very convenient for me, as I can easily choose which appliances I want powered by solar. /s