# My 240 volt outlet seems to be delivering 219 volts

I am seeking help with my confusion about where my problem lies and what to do next.

I had a home renovation and got new appliances and upgraded circuit box two plus years ago. But not the "heavy up" with the power company for the power coming into my house. I was told it wasn't needed. I am not sure that is correct. I have had problems with my oven and stove not heating up to proper temps.. or not holding the heat as needed.

Had the electronic works replaced twice. The second time, the repair guy tested the outlet that powers the range. Each "hot" delivers 120 but when both hots are tested together the voltage adds up only to 219 volts. Does that make sense? How can this be?

I was advised to call my electrician who had put in all the new wiring and new circuit box at renovation. He charged me \$\$\$\$ to find again that 219 volts come into what should be 240 volt outlet. He found then that 219 volts come into the main power circuit box... and the same at the outside of my house where the meter is. A few weeks later he is now saying that no, it is 219 amps coming into the house and all is fine. I think he is double talking me. And I am still left with 219 volts coming out of the outlet that is supposed to deliver 240.

What should I do? I called the power company and their report to me was inconclusive.. they can't tell me over the phone what they found beyond, "the power coming into your house is adequate." what that means is not clear. Should I have them return while I am home and they can explain what they found? Should I get another electrician in? Or something other course of action. Thanks for your thoughts on these issues.

To all responding- Thanks so much. For clarification... when i wrote that each hot when separately test with multimeter measure at 120 but when measured together they measure not 240 (120 +120 should =240 total, yes?) but 219, all measurements where taken with multimeter sensors in the socket.... that is with oven unplugged. We were testing how much power is coming through the outlet. The oven repair guy said that only 219 is being delivered to what is an oven that is supposed to run on 240. The thought is that the electronics can't keep up with the temperatures set for cooking. also just so folk kow i think my electrician is not confused about volts vs amps. it is a language barrier... or he is trying to be cagey with me about what he thinks the problem is. Also the prong is 4 prong. and because the central panel box measures the same way with 219 volts, and the panel box outside with the meter reads 219 volts, I remain wondering if 100amps are being delivered to my house of the 200 amps that i think my house needs to run central air, appliances, etc.
Actually this goes back to me wondering what the heck kinda of amperage and voltage comes into my house... from the power company and why they can't tell me what that is... They won't tell me at leasat.

• If your "electrician" is confusing amps and volts, you def. need to get a different electrician. Regarding your original problem, this sounds like a power company problem. Maybe some weird take off of a 3 phase system? I don't know enough to speculate more. What part of the country are you in? Mar 6 '20 at 1:06
• That lower voltage is only going to slow your oven down 17%, and even that, only during initial warmup. So a 6 minute warmup will now take 7. Mar 6 '20 at 1:27
• This electrician sounds like kind of a goofball. Confusing amps and volts is a pretty silly thing to do if you are a normal person -- it is borderline negligent for a certified professional. Mar 6 '20 at 3:33
• By the way, 219 amps is a lot of amps. 219 volts x 219 amps = 48 kilowatts, and if you're using that much electricity all the time, then 48 kilowatts x \$0.12/kWh = \$50000 a year... Mar 6 '20 at 11:07
• 219V from adding up two 120V lines corresponds to a phase difference of ~126 degrees. That's pretty close to 120 degrees, which is what you'd expect from putting in two of the three phases of 3 phase x 120V. Mar 7 '20 at 12:53

240V is a nominal value. Depending on how far away you are from the power station or other factors, it could be higher or lower, 219V is a perfectly reasonable value. It is also unrelated to the problems you're having with your oven. Most ovens have an internal thermostat that controls whether or not the heater operates. When you don't get enough voltage, your oven will still heat up to the given temperature, it would just take longer. (Unless the voltage is so low that it's not able to hold heat, but 219V is perfectly fine.) Also, I'll note that most oven thermostats aren't that precise; it can pay to have an oven thermometer around if you need precision.

At this point, the electrical system appears fine up to the point where it hits the oven. If both the stove and oven are the same appliance, I'd consider the possibility that something's off inside them. For example, if the plug isn't connected properly to the actual oven, and the oven only has one 120V rail, you could indeed run into problems.

• 120v from each hot to the common neutral is a perfectly reasonable value. 219v hot-to-hot is a perfectly reasonable value. Both of those measurements in the same house at the same time is insanely far from reasonable -- it means either you are measuring wrong, or you are buying broken electricity. Mar 6 '20 at 3:36
• @A.I.Breveleri -- he could very well be in a place where that's roughly his normal service voltage -- 120/208V service is a thing Mar 6 '20 at 4:08
• Also 240V is the older specification. To harmonise between the various "standard" levels of 110V, 220V and 240V, the industry standardised internationally on 115V and 230V about 30 years back, with tolerance bands which included the old values so equipment didn't need to be replaced immediately. Older substations may still run at the older voltages, but newer ones are likely to run at the new nominal level, i.e. 230V. Mar 6 '20 at 10:52
• It is also reasonable that 120+120=/=240. It depends on the phase difference, phi. Mar 6 '20 at 11:57
• @IanKemp -- yeah, 208Y/120 is a very common system, and 120/208 is simply what you get when you grab any two of the three phases available. Mar 7 '20 at 0:25

"Each "hot" delivers 120 but when both hots are tested together the voltage adds up only to 219 volts. Does that make sense? How can this be?"

Normally the voltage between the two hot legs is equal to the sum of the separate voltages from each hot leg to the neutral. In order for this to happen the hot legs must be exactly 180 degrees out of phase.

If you are truly measuring 120v from hot 1 to neutral, 120v from hot 2 to neutral, and 219v from hot 1 to hot 2, then the power that the utility company is delivering to your house has a phasing problem. The utility company will tell you that this is impossible.

It is not impossible, but it is probably very rare and hard to believe. You must be very confident that your voltage measurements are accurate before proposing this diagnosis.

It is no surprise that your electrician would not think of this, and he may not even have the proper equipment to check for it1.

You could give an electrician more \$\$\$\$ to check the phase separation of your hot legs, or you could just call the power company and confidently insist that you had an electrician out and he says the line is not phased properly.

Look up "lissajous figures" and how they are formed. Tell the power company that your electrician showed you something on a screen that he said should be a straight sloping line, but it looked like a couple of sagging ropes. That should wake somebody up.

1. I would use an oscilloscope with X * Y inputs. The lissajous figure must be a straight line with a 45 degree slope (thanx el duderino).
• No, this could very well be close to normal phasing, on a 120/208V 2p3w "2 out of 3" system derived from a 3p4w 208Y/120 service or network Mar 6 '20 at 4:01
• I did not know that was even a thing anywhere in North America. -- See, that's why you don't hire a EE to rough-in structure wiring. Mar 6 '20 at 4:13
• I was wondering if it could be 120/208 instead of 120/240 - but again it wouldn't be correct - i.e., instead of 21 V low it would be 11 V high. Mar 6 '20 at 4:35
• @manassehkatz-Moving2Codidact -- yeah, it'd be running a bit high for a 120/208 service Mar 6 '20 at 4:41
• @A.I.Breveleri The lissajous figure for two legs 180 out of phase would be a straight line, not a circle, which would indicate 90 degree phase shift. And as NoSparks says, the way legs work on US mains power makes a phase issue pretty much impossible. My guess is that it's because typically measurement of ac voltages uses RMS which is not linear, so small higher harmonics might cause the voltages to not add up exactly. Mar 6 '20 at 5:26

## Get the ability to measure "it" yourself

I would get two units called a "Kill-A-Watt". These are simple plug-in devices that let you measure voltage and current from 120V circuits. You're out to measure a 240V circuit, but that is made of two banks, or rather poles, of 120V circuits.

Plug one in somewhere. Then plug another one in somewhere else, that's on a different pole. The voltage will be slightly different. You might find both poles right in your kitchen.

Now, watch the two voltages as different appliances cycle on and off.

It's common for voltages to dip slightly when loads are added. You may see that on one "leg" vs the other.

Now, I bet when they upgraded your electrical service, they did not upgrade the service drop wires from the pole to the house. That is perfectly normal and common. That's because people who buy 200A service don't typically use all that much of it. Why upgrade everyone's service drop when only a few people actually need it? And they learn that from the energy meter, and in theory they're supposed to roll a truck and change your service drop if it's warranted.

We can test that theory by looking at your voltages as appliances cycle on and off. When a bunch of 240V appliances throw on at once, if this theory is correct, the voltage will dip, about equally on both "legs" - so your numbers might be 112V and 110V. With them all off, you'll see around 240V in total.

## But beware the lost neutral

If your range is the obsolete and dangerous 3-prong plug/socket (NEMA 10-50 or 10-30: angled blades), there can be strange goings-on if that neutral wire develops a problem. I mention this because of the lethality; a lost neutral energizes the chassis of the oven, so don't take any chances around that.

However, since you said an electrician re-ran the range power supply cable, Code absolutely required that be done with separate neutral and ground. This was definitely done if you see a 4-prong (NEMA 14-50; parallel blades) recep for a common range with a common oven light. Some exotic 240V-only ranges don't need neutral, and it's fine for them to use a grounded 3-prong recep (NEMA 6-50; parallel blades).

The -50 figure is the amp rating. Using -30 is also acceptable, those connectors are slightly different.

If you see the obsolete angled blades, that's a concern. Hopefully, behind the wall, the electrician ran the correct cable (/3+ground). If the electrician ran /2+ground to a NEMA 10, that would've been a big screw-up -- misusing a /+ground's ground wire as neutral was always illegal (even when new NEMA 10 installations were legal, e.g. 1960). But I see it done all the time. Super lazy.

• I think that this is the right approach-- the voltages not quite adding up is likely a red herring and it doesn't seem like the difference the OP is describing would be enough to cause the problems they're seeing anyway. I would add that if he does do the test you describe and sees no voltage drop, he might want to hire a (competent!) electrician to test the voltage at the outlet that the stove is on while the stove is running, since it could be the case that the circuit for the stove was wired with inadequately gauged wire (which would be a pretty urgent situation). Mar 6 '20 at 14:49
• re " ... This was definitely done if you see a 4-prong (NEMA 14-50; parallel blades) recep ..." -> Definitely is such a strong word :-). It means that the electrician knowswhat he SHOULD have done, and probably did, but ... . (I know that you know that). Mar 7 '20 at 23:34

Before I got into phasing issues and lissajous figures (wow), I would first repeat those voltage measurements at the power input to your house, WITH and WITHOUT the stove and the oven turned on to compare between loaded and unloaded conditions. I would expect some drop in volts when both oven and stove are turned on eg 120v dropping to say 110v under load. If more than that then it suggests your wiring is not heavy enough to support these appliances and you need a proper electrician who does not confuse volts and amps!

Re-confirm those 120,120,219 measurements at your main board, that means finding someone who knows how to operate a voltmeter and getting them to do 5 minutes work. This is a weird fault and I'd want to be triple sure before raising the alarm.

If the numbers still don't add up (I mean that literally and figuratively) contact the power company and tell them that you suspect that there's something wrong with your neutral. (It's not mid way between the phases - that's something wrong)

They should send someone out with the equipment needed to do a proper investigation. It might take them a couple of visits, to me this is an odd fault.

• I have a hunch the 120V numbers are from the oven socket with the socket unplugged (so oven off obviously), and the 219V is with the oven loaded up. Mar 6 '20 at 18:18
• no. both are measured with oven unplugged. Mar 6 '20 at 19:35

Here's a good -- and entertaining -- video by ElectroBOOM explaining how one gets a high voltage in a 120V home.

The 219V looks suspect; the voltage between any two phases of a three-phase supply should be about 208V. Since the magnitude of each phase has been tested to be correct (120V), then the only explanation left is that somehow the phase angle is not 120°. This might be caused by capacitance or inductance somewhere along the supply line.

• The OP didn't mention that he was on a three phase system. He's implying he should have 120/240V which would be single phase before the transformer and 120/240v after.
– JACK
Mar 6 '20 at 16:12
• @JACK I think 3ph is implied here: Each hot when separately tested (meaning, 2 hots + 1 neutral = 2 phases at least) = 120V, but when measured together (I translate this as "hot to hot") = 219. But I admit it's just a guess from me; without looking at the actual wiring diagram I cannot be 100% certain. Mar 11 '20 at 1:56

Much of this discussion is over 120V + 120V coming out to 219 V. 1 volt is not significant in an oven. If the problem is that the stove and oven do not heat well, it can be the way it is wired to the plug. Some can be wired for 210, 220, or 240V. Also, the voltage needs to be checked there, not the outlet. If the problem is that the oven does not hit exactly the temperature it is set for, there are several explanations. Some ovens do not heat evenly, so some places will be cooler. Your oven thermometer may not be accurate. Or, your oven thermostat may be wrong. If it is under warrenty, you can try to get it replaced. Or you can just make a note that if you want 400°, set it to 425°. The difference may not be as simple as "add 25°", it may be less at low temps.

• Kent, thanks for commenting. The difference is not 1 volt. I need 240 volts not 220 volts for proper oven operation. Also, I have tried to do as you suggest with setting temps higher, but that doesn't work reliably. The oven is not constantly under the same degree of temp. than it is set at. there is a chance I just have a bad oven, yes, but now I know that i am not getting 240 volts at this outlet I need to solve that it seems. Mar 6 '20 at 19:45
• It's a 21V difference, not a 1V difference... Mar 6 '20 at 20:01
• 120V+120V=240V, not 220V. Slight mistake but easily made. Mar 6 '20 at 20:15

It is delivering exactly what it should. They way you measured it.

Do you know 3 phase electricity and how to properly measure it?

• They'd know if they had a 3ph service of their own, I reckon. Also, we need to know who their utility is -- PEPCO doesn't seem to deliver 120/208V 2-phase service? Mar 8 '20 at 20:43
• IT is pepco, and now I don't know about 3 phase and how to properly measure it. Sounds like I need to call a better electrician? Mar 9 '20 at 20:31

## I'd have another electrician come in and measure it themselves, get a good second opinion

What you're describing here seems...off-kilter. Either something caused the service voltage to sag between measurements (which chould very well have happened if they were taken sequentially), or there is something bizarre going on, since PEPCO (aka the OP's electric utility) does not provide 120/208V "2 out of 3" service anywhere in the DC area as per their service handbook, and the OP would definitely know if they had a full 208Y/120 three phase service (if nothing else, the main panel'd be different in noticeable ways). Furthermore, even if this was 208Y/120 being fed to them, it's running rather hot for such a service.

In any case, the best way to handle this would be to have a different electrician come in and measure your situation, or measure it yourself for that matter as Harper describes how to do.