Household voltage question

I am far from an electrician and would only ever hire a licensed electricia n to do any major electrical work on my home. But I am reasonably comforta ble measuring AC voltages.
In 2013 we had a 240V electric car charging station installed in our garage . 50 amp breaker, 6 gauge wire. The actual unit is convenient, because it has a plug and is designed to plug in to a 240V outlet. For reference, it is Leviton EVB40-SPT Level 2 surface mount charging station. So we had our electrician install and wire a 240V receptacle on a dedicated 50A circuit, mounted the unit on the wall above the receptacle and plugged it in. All appeared to work just fine for about two years.
Then, a couple of years in, it started having this issue where the unit wou ld rapidly click (on/of) when charging (though it did always charge the car - Nissan Leaf). When trying to troubleshoot this, I noticed that turning the garage light on (different circuit) or turning on another light in the adjacent room on (other different circuit) would cause the clicking to stop . It's hard to say how long this problem existed prior to discovery, since normally the car would charge at night when we were asleep (taking advanta ge of our dual rate electric). But since we would occasionally plug it in during the day for a recharge, we eventually noticed this issue.
Recently (since we are between electric cars) I have sent the unit back to the company to be tested.
For further troubleshooting, I recently measured the voltage at the recepta cle. The first time I did this, I measured the voltage at around 238V (ove r the course of a few minutes I measured the voltage at values between 238V and 238.8V) - with garage lights on. I measured the next day and the volt age was closer to 242V (slowly fluctuating between 241V and 242V). Both ti mes, during the few minutes I was measuring, the voltage would slowly fluct uate within about half a volt of the avg. value. I also measured the volta ge between the neutral and hot terminals and found that those values were e ach about half of the total (as expected), but importantly, that they were the same value - though when I was measuring the first time around, I thoug ht that one side was consistently about 0.2V higher than the other side. I didn't see that 0.2V variation the second time I measured. On my second t est, I remembered to turn the lights on and off to check for differences. I found no discernible difference in voltage with the lights on or off.
I know that household voltage fluctuates, but I can't seem to find a defini tive answer about how much fluctuation is normal or acceptable. Furthermor e, when talking to the tech on the phone earlier, he made the claim that th e voltage had to be *above* 240. That just sounded completely wrong to me. I was pretty sure that any appliance was supposed to work between a range of voltages. If anything, I might be worried about voltages above 240, sin ce 220-240V is often a range I hear.
Can someone on here with electrical wiring knowledge let me know if it soun ds like the voltage I measured at this outlet is within the normal range fo r household service, and if the fluctuation that I measured seems normal?
Thanks.
-J
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< snips >

see page 49 - 50 of this document for normal voltage range.
http://www.hydroone.com/MyHome/MyAccount/ConditionsofService/Documents/HydroOne_Conditions_of_Service_2015_ENGLISH.pdf
Momentary fluctuations or transients would not be detectable without specialized equipment. These can be caused by many things - internal and external to your service. John T.
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On 8/23/2016 2:46 PM, J wrote: > I am far from an ele ctrician and would only ever hire a licensed electrici an to do any major electrical work on my home. But I am reasonably comfortable measuring AC voltages. > > In 2013 we had a 240V electric car charging station i nstalled in our garage. 50 amp breaker, 6 gauge wire. The actual unit is convenient, because it has a plug and is designed to plug in to a 240V outlet. For refe rence, it is Leviton EVB40-SPT Level 2 surface mount c harging station. So we had our electrician install an d wire a 240V receptacle on a dedicated 50A circuit, m ounted the unit on the wall above the receptacle and p lugged it in. All appeared to work just fine for abou t two years. > > Then, a couple of years in, it star ted having this issue where the unit would rapidly cli ck (on/of) when charging (though it did always charge the car - Nissan Leaf). When trying to troubleshoot t his, I noticed that turning the garage light on (diffe rent circuit) or turning on another light in the adjac ent room on (other different circuit) would cause the clicking to stop. It's hard to say how long this prob lem existed prior to discovery, since normally the car would charge at night when we were asleep (taking adv antage of our dual rate electric). But since we would occasionally plug it in during the day for a recharge , we eventually noticed this issue. > > Recently (si nce we are between electric cars) I have sent the unit back to the company to be tested. > > For further t roubleshooting, I recently measured the voltage at the receptacle. The first time I did this, I measured th e voltage at around 238V (over the course of a few min utes I measured the voltage at values between 238V and 238.8V) - with garage lights on. I measured the next day and the voltage was closer to 242V (slowly fluctu ating between 241V and 242V). Both times, during the few minutes I was measuring, the voltage would slowly fluctuate within about half a volt of the avg. value. I also measured the voltage between the neutral and h ot terminals and found that those values were each abo ut half of the total (as expected), but importantly, t hat they were the same value - though when I was measu ring the first time around, I thought that one side wa s consistently about 0.2V higher than the other side. I didn't see that 0.2V variation the second time I me asured. On my second test, I remembered to turn the l ights on and off to check for differences. I found no discernible difference in voltage with the lights on or off. > > I know that household voltage fluctuates , but I can't seem to find a definitive answer about h ow much fluctuation is normal or acceptable. Furtherm ore, when talking to the tech on the phone earlier, he made the claim that the voltage had to be *above* 240 . That just sounded completely wrong to me. I was pre tty sure that any appliance was supposed to work betwe en a range of voltages. If anything, I might be worri ed about voltages above 240, since 220-240V is often a range I hear. > > Can someone on here with electric al wiring knowledge let me know if it sounds like the voltage I measured at this outlet is within the normal range for household service, and if the fluctuation t hat I measured seems normal? > > Thanks. > > -J >
Well within normal limits.
You may want to check at other times of day though. I was burning out bul bs in the bathroom and it ws only in the morning. I c hecked and found that at 6;45 AM to voltage was 134 instead of 120. The rest of the day was good.
Tu rns out at a local substation they increased the volta ge in the morning to cover the extra draw as industr y came on line. They over compensated though. Once adjusted it was back to a low tolerance.
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<snip>

In the USA, voltage can vary by 5% (RMS) +/-. Each side of the 240VAC circuit may vary independently depending on how the load is distributed in the rest of the house. Fluctuations will occur as load is introduced and removed both within your house and depending on your neighborhood, as load is introduced by your neighbors.
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table measuring AC voltages.

t has a plug and is designed to plug in to a 240V outlet. For reference, i t is Leviton EVB40-SPT Level 2 surface mount charging station. So we had o ur electrician install and wire a 240V receptacle on a dedicated 50A circui t, mounted the unit on the wall above the receptacle and plugged it in. Al l appeared to work just fine for about two years.

ar - Nissan Leaf). When trying to troubleshoot this, I noticed that turnin g the garage light on (different circuit) or turning on another light in th e adjacent room on (other different circuit) would cause the clicking to st op. It's hard to say how long this problem existed prior to discovery, sin ce normally the car would charge at night when we were asleep (taking advan tage of our dual rate electric). But since we would occasionally plug it i n during the day for a recharge, we eventually noticed this issue.

ver the course of a few minutes I measured the voltage at values between 23 8V and 238.8V) - with garage lights on. I measured the next day and the vo ltage was closer to 242V (slowly fluctuating between 241V and 242V). Both times, during the few minutes I was measuring, the voltage would slowly flu ctuate within about half a volt of the avg. value. I also measured the vol tage between the neutral and hot terminals and found that those values were each about half of the total (as expected), but importantly, that they wer e the same value - though when I was measuring the first time around, I tho ught that one side was consistently about 0.2V higher than the other side. I didn't see that 0.2V variation the second time I measured. On my second test, I remembered to turn the lights on and off to check for differences. I found no discernible difference in voltage with the lights on or off.

ore, when talking to the tech on the phone earlier, he made the claim that the voltage had to be *above* 240. That just sounded completely wrong to m e. I was pretty sure that any appliance was supposed to work between a rang e of voltages. If anything, I might be worried about voltages above 240, s ince 220-240V is often a range I hear.

for household service, and if the fluctuation that I measured seems normal?
Your voltage readings are not unreasonable however I am troubled by that cl icking on and off that you mentioned. You could have a loose connection so mewhere on that circuit or on the main service to the house. Have you noti ced any lights flickering in the house when the car is not plugged in? Are other 240 volt appliances operating okay such as the stove, water heater, or air conditioning? Any other strange electrical phenomenons going on?
If so I suggest that you have the power company come out and check their li nes to your house. Then have an electrician tighten the connections in you r electrical panel.
John Grabowski http://www.MrElectrician.TV
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On 08/23/2016 01:53 PM, John G wrote:

> in your electrical panel.
1+
I have seen this before. If the wires are not tightened properly at the panel, it could cause a fire.
The symptom I saw was that if you turn the lights on (not off) in the hall, the lights in the living room got brighter.
In this instance, the power company had to remove about six inches of burnt wire and reattach at the panel
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On 8/23/2016 2:21 PM, T wrote:

I had the same problem. Turned out to be a poor neutral connection at the power pole.
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On 2016-08-23 5:42 PM, AL wrote:

especially windy it was really bad, local electric company jumped on it. Guy was here within the hour, inspected my panel, said it was one of the neatest panels he had ever seen, it must be the company's problem, called in a crew for that night, they fixed it up. Floating neutral at the top of our mast from the meter, all fixed up and no problem since, that was about 12 years ago.
--
Froz....

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Thanks for the input. After speaking with a more knowledgeable tech at the company, I found that there was nothing wrong with those voltages that I m easured. However, that doesn't help me resolve my problem with the car cha rger.
According to the knowledgeable tech, the clicking is almost certainly cause d by voltage fluctuations, but not the noticeable kind that make your light s dim noticeably (more on that later). Instead, he suggested that there is noise on the line that is causing voltage spikes - very brief voltage fluc tuations that might only last milliseconds at a time, and therefore not be measurable on my crude multimeter, but would cause the safety circuitry in the charging station to briefly suspend the flow of electricity to the car - that's what all the clicking is. He suggested that this could be caused by loose ground connection at the panel, or that there could be something o n another circuit introducing noise. I thought that it was odd that turning lights on would mitigate the problem, but he said it might be that the ext ra loads could actually help to dampen the noise (or something like that) s o that the voltage fluctuation at the charging station would not be enough to cause the problem.
So, further diagnosis required.
Now, when he brought up these brief voltage fluctuations, I said oh, like h ow when the compressor for our geothermal heat exchange system kicks in the lights dim for a fraction of a second? No - apparently that's a different but possibly related problem. I can't decide from searching the internet, whether that is normal or a real problem - depends who's talking. Our hous e, built in '77 has a 200 amp service (I think). but we live in a rural ar ea, and are literally the last house on the power line, so distance from th e transformer could be a problem.
So, there could be multiple issues.
I've had a number of CFL and LED bulbs fail prematurely (IMO), but I always chalked this up to new technology not being particularly robust. Now I wo nder if these failures are really due to a problem with our electric servic e or wiring.
Wondering if the next step is to have an electrician come have a look or to ask the power company to test things on their end first - apparently they can hook up some kind of data logger.
-J
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Top Post Alert - too long sentences
Trouble-shooting - of a fresh occuring problem - is best. < by a professional with proper instruments >
vs : trouble-shooting an old intermittent occasional problem - after the homeowner and all his expert friends & neighbours have fiddled around with things ..
Can you shut off the geo-heat-pump and see if that is the problem ? Any new neighbours on your supply feeder ? Solar / wind / industry ?
.. far too many variables for this guessing game ..
Good Luck. John T.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Thanks for the input. After speaking with a more knowledgeable tech at the company, I found that there was nothing wrong with those voltages that I measured. However, that doesn't help me resolve my problem with the car charger.
According to the knowledgeable tech, the clicking is almost certainly caused by voltage fluctuations, but not the noticeable kind that make your lights dim noticeably (more on that later). Instead, he suggested that there is noise on the line that is causing voltage spikes - very brief voltage fluctuations that might only last milliseconds at a time, and therefore not be measurable on my crude multimeter, but would cause the safety circuitry in the charging station to briefly suspend the flow of electricity to the car - that's what all the clicking is. He suggested that this could be caused by loose ground connection at the panel, or that there could be something on another circuit introducing noise. I thought that it was odd that turning lights on would mitigate the problem, but he said it might be that the extra loads could actually help to dampen the noise (or something like that) so that the voltage fluctuation at the charging station would not be enough to cause the problem.
So, further diagnosis required.
Now, when he brought up these brief voltage fluctuations, I said oh, like how when the compressor for our geothermal heat exchange system kicks in the lights dim for a fraction of a second? No - apparently that's a different but possibly related problem. I can't decide from searching the internet, whether that is normal or a real problem - depends who's talking. Our house, built in '77 has a 200 amp service (I think). but we live in a rural area, and are literally the last house on the power line, so distance from the transformer could be a problem.
So, there could be multiple issues.
I've had a number of CFL and LED bulbs fail prematurely (IMO), but I always chalked this up to new technology not being particularly robust. Now I wonder if these failures are really due to a problem with our electric service or wiring.
Wondering if the next step is to have an electrician come have a look or to ask the power company to test things on their end first - apparently they can hook up some kind of data logger.
-J - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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On Tuesday, August 23, 2016 at 9:10:57 PM UTC-4, J wrote:

measured. However, that doesn't help me resolve my problem with the car c harger.

hts dim noticeably (more on that later). Instead, he suggested that there is noise on the line that is causing voltage spikes - very brief voltage fl uctuations that might only last milliseconds at a time, and therefore not b e measurable on my crude multimeter, but would cause the safety circuitry i n the charging station to briefly suspend the flow of electricity to the ca r - that's what all the clicking is. He suggested that this could be cause d by loose ground connection at the panel, or that there could be something on another circuit introducing noise. I thought that it was odd that turni ng lights on would mitigate the problem, but he said it might be that the e xtra loads could actually help to dampen the noise (or something like that) so that the voltage fluctuation at the charging station would not be enoug h to cause the problem.

he lights dim for a fraction of a second? No - apparently that's a differe nt but possibly related problem. I can't decide from searching the internet , whether that is normal or a real problem - depends who's talking. Our ho use, built in '77 has a 200 amp service (I think). but we live in a rural area, and are literally the last house on the power line, so distance from the transformer could be a problem.

wonder if these failures are really due to a problem with our electric serv ice or wiring.

y can hook up some kind of data logger.

When you have the problem, I'd start by having someone at the panel open the breakers for everything else, one at a time, and see if you can narrow it down. It's possible something on one circuit is the problem and that somehow having the lights turned on, manages to shunt enough of it that the car charger no longer objects. If that's what's going on they must have a charger that is unusually sensitive to this kind of thing, most power supplies aren't.
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On Wednesday, August 24, 2016 at 9:43:54 AM UTC-4, trader_4 wrote:

I measured. However, that doesn't help me resolve my problem with the car charger.

ights dim noticeably (more on that later). Instead, he suggested that ther e is noise on the line that is causing voltage spikes - very brief voltage fluctuations that might only last milliseconds at a time, and therefore not be measurable on my crude multimeter, but would cause the safety circuitry in the charging station to briefly suspend the flow of electricity to the car - that's what all the clicking is. He suggested that this could be cau sed by loose ground connection at the panel, or that there could be somethi ng on another circuit introducing noise. I thought that it was odd that tur ning lights on would mitigate the problem, but he said it might be that the extra loads could actually help to dampen the noise (or something like tha t) so that the voltage fluctuation at the charging station would not be eno ugh to cause the problem.

the lights dim for a fraction of a second? No - apparently that's a diffe rent but possibly related problem. I can't decide from searching the intern et, whether that is normal or a real problem - depends who's talking. Our house, built in '77 has a 200 amp service (I think). but we live in a rura l area, and are literally the last house on the power line, so distance fro m the transformer could be a problem.

I wonder if these failures are really due to a problem with our electric se rvice or wiring.

hey can hook up some kind of data logger.

I think I would attack this from the opposite direction. I would shut off *everything* except for the charging circuit and see what happens. If there is no clicking, I would begin to turn on other circuits and add loads until the problem shows up. That would (to some extent) eliminate the charging circuit as the root cause.
However, just because the clicking started when the e.g. third circuit was turned on, I wouldn't immediately blame that circuit. I'd circle back and turn off the others. It could be a combination of circuits/cumulative load from multiple circuits that's causing the problem. Maybe even one side of the panel.
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DerbyDad03, excellent strategy! Very well reasoned. I'll give it a go when I have the opportunity.
-J
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On Friday, August 26, 2016 at 11:46:20 AM UTC-4, J wrote:

Glad you liked his so much better than mine, which was essentially the same thing and suggested first.
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