Unreasonable Electrical Consumption

[SAS]

I have a medium sized house in Maryland. When we moved in we immediately noticed that our electrical consumption seemed unreasonable. But we also had my 90+ year old father in law and a full time aide living with us. In addition to keeping the heat running late into the spring, he also ran multiple space heaters - sometimes even in the summer. He also required frequent laundry cycles. And in the summer we have a medium sized pool and run the filter most of the time.

Now, however, my father in law has passed away and it's just my wife and me. Our consumption in October, when neither the heat nor the AC were run much if at all was 2,489 KWH! I took a clamp meter and measured the amperage in the cables feeding the main, 2 on each of 2 panels. In total it averaged right around 10 amps over several readings. I recognize that when the well pump or the refrigerator compressor, or indeed the heat pump, kick in those readings will go up, but if I assume a steady state of 10 amps, then I've got roughly 900 KWH for the month. (10*120/1000*24*31). It's hard for me to see how I get up to 2,489 KWH.

Any suggestions? I know it's unlikely that the meter is bad, but what am I missing? Is there some fallacy in how I am calculating usage? I had my wife turn on appliances of known wattage and validated that I saw an increase in amps on the meter that corresponded with the stated amperage of the device.

 

[Jadnashua]

Shut your main breaker off and check your meter to see if it is still spinning. If it stopped, start turning things back on, one at a time, and notice what is causing it to rotate at a high rate. If the meter does not stop when you shut the main off...there's something strange going on that needs to be investigated. Compare that with what you think is actually running. Space heaters can suck up some significant power. Your pool pump could be drawing a lot as well. Do you have a pool heater?

Your bill is for the previous month, and in some situations, they do an estimated bill if for some reason, they can't read your actual meter. Make sure yours is for actual use verses estimated. If it is based on estimated use, the next time they actually read it, it should be adjusted.

 

[Sponsor]

 

[Reach4]

I took a clamp meter and measured the amperage in the cables feeding the main, 2 on each of 2 panels.

I agree. Turn off the water heater and other loads to the extent you can. Flip off breakers, and you can find the circuit sucking power. You can do that while watching your clamp meter, or communicate with somebody watching the meter. The problem with the clamp meter is that you will have to measure the current for both legs.

Note that each single pole breaker will only get power from one leg. And it is not like the left column or right column. Instead, each leg alternates left or right as you go down the breaker rows. The reason for that is that adjacent slots always use opposite legs. That allows using a 2-pole breaker for 240 volt loads.

The well would have been a good candidate, although it seems less likely since you observed that increase when the pump runs.

It will be interesting to read what you find.

 

[SAS]

I did shut the mains in both panels, and as expected the meter sopped. I’ve checked the sum of the current in the four feeder cables on several occasions and it is fairly steady at roughly 10 amps. I’m sure it will go up quite a bit when a major appliance kicks in, but I can’t see how it could average about 28, which is what it would have to for me to use 2,489 KWH in one month. Am I calculating incorrectly?

In the meantime I read the meter and will read it again tomorrow to see what one day’s use is.

 

[Reach4]

I did shut the mains in both panels, and as expected the meter sopped. I’ve checked the sum of the current in the four feeder cables on several occasions and it is fairly steady at roughly 10 amps.

1. Four feeder cables? What are those 4? Are you including the neutral and ground? The current in the ground wire should be very close to zero.
2. What do you mean the sum of the current of the 4 cables was about 10 amps? Are you saying they were something like 4 amps, 3 amps, 2 amps, and 1 amp?

2489 kWh would be about 14.4 amps in each hot 24 hours per day for 30 days. I presume you are adding those together to get about 28.

 

[SAS]

1. Four feeder cables? What are those 4? Are you including the neutral and ground? The current in the ground wire should be very close to zero.
2. What do you mean the sum of the current of the 4 cables was about 10 amps? Are you saying they were something like 4 amps, 3 amps, 2 amps, and 1 amp?

2489 kWh would be about 14.4 amps in each hot 24 hours per day for 30 days. I presume you are adding those together to get about 28.

I have 2 panels, hence the 4 feeder cables. And yes, I am adding the amps together to get 10. 28 is the number I backed into from 2489 for the month.

 

[SAS]

Could it be the hot water heater? I was able to measure the usage on that circuit when it kicked in and it was roughly 23 amps on each of the two feeds. Here's the decal on the unit:

Doesn't that mean that it should only pull a total of 5500/240 = 23 watts?

 

[Jadnashua]

When measuring amps on a 240vac (or 120vac) circuit...all of the power that goes into one lead, comes out the other. You don't add the two together...remember, it's a closed circuit...the power goes through the device and returns to the source. The reason it does move is because of the polarity, but it is the same current.

So, 23A or so on either lead would indicate 5500W. Now, if the WH was already hot, that should drop to zero amps when it is off. If it has a constant draw, one symptom would be that the water was extremely hot, and not being controlled by the thermostat.

 

[SAS]

When measuring amps on a 240vac (or 120vac) circuit...all of the power that goes into one lead, comes out the other. You don't add the two together...remember, it's a closed circuit...the power goes through the device and returns to the source. The reason it does move is because of the polarity, but it is the same current.

So, 23A or so on either lead would indicate 5500W. Now, if the WH was already hot, that should drop to zero amps when it is off. If it has a constant draw, one symptom would be that the water was extremely hot, and not being controlled by the thermostat.

Thanks, I should have known that (and I think that I once did). So now I can rule out the hot water heater. Oh well, I thought maybe I had an answer, but it's back to the drawing board.

edit: Actually, adding them is what I did want to do, since I was adding all of the amps together and then computing KW by multiplying by 120 and dividing by 1000. What I did wrong was compare that 46 amps at 120 to 23 amps at 240 and not realize that they were equivalent in terms of KW.

 

[Reach4]

I have 2 panels, hence the 4 feeder cables. And yes, I am adding the amps together to get 10. 28 is the number I backed into from 2489 for the month.

Usually with 2 panels, one is a subpanel. In that case, the subpanel is powered via a breaker in the main panel. The power used via the subpanel is part of the power supplied through the main feeders into the main panel. So in that case, you only want to measure the currents on the two hot supply lines to the main breaker.

 

[SAS]

Usually with 2 panels, one is a subpanel. In that case, the subpanel is powered via a breaker in the main panel. The power used via the subpanel is part of the power supplied through the main feeders into the main panel. So in that case, you only want to measure the currents on the two hot supply lines to the main breaker.

The second panel is not a sub panel; it’s an independent main.

 

[WorthFlorida]

Do you have two meters? With one meter is one main and one sub panel? Two meters, two main panels.

Most likely you have a digital meter, most of the country has switched over. If you do then you can go online to your power companies web site, login to "myaccount" or something similar and you can view your daily usage usually down to the hour. The latest usage is usually the day before. This can give you a clear picture of power consumption by time of day. Do check you bill for the start day for your monthly bill. Your last bill may have included part of September.

Does your AC/heat pump system have an aux electric heater in the air handler?

 

[SAS]

Unfortunately I don't have a digital meter, but I just purchased one for the hot water heater and will install it along with a timer this weekend. I'm still not sure how I manage to use so much electricity. Looking back over the usage for two years, in those months when there is very little heating or cooling, I still manage to average about 72 kwh per day. That comes out to an average usage of 25 amps at 120 volts. When I spot check the amperage draw, the "steady state" is about 10-12 amps. I'm hoping that the answer is the hot water heater. It pulls 5500 watts at 240 volts, which should be equivalent to 46 watts at 120 volts. If it is running 8-10 hours a day, it just might account for that usage. At least with the meter I'll be able to see how much current the hot water heater is actually drawing over the course of a day.

One related question for anyone who has an opinion: would you put the timer before or after the meter? It's simpler because of knockout locations, etc. to put the meter first. I don't think it would matter much, because it's a digital timer and I can't imagine that it would draw much current. I suppose I could also just measure how much current the timer is drawing when the hot water heater is off and ignore that amount should it be more than negligible.

 

[WorthFlorida]

As mentioned before if it was the water heater you would have very hot water. Electric elements are nearly 100% efficient and it would be a runaway thermostat causing the issue. If you're sure the water heater is not heating water when you have the clamp meter on it, the current would be zero. Above you gave readings while you checked it and the current draw was normal.

I would call the electric company and request a meter change out. They'll also have statistics on the average usage per home in your area just to verify your claim. You may want to ask any of your neighbors on their power consumption especially if they have an electric water heater. A factor in electric water heater usage is the cold water temperature. My brother's cabin home in VT the well water must be 45 degrees where here in Florida it's about 75 degrees. It takes a lot of energy to heat water.

 

[SAS]

As mentioned before if it was the water heater you would have very hot water. Electric elements are nearly 100% efficient and it would be a runaway thermostat causing the issue. If you're sure the water heater is not heating water when you have the clamp meter on it, the current would be zero. Above you gave readings while you checked it and the current draw was normal.

I would call the electric company and request a meter change out. They'll also have statistics on the average usage per home in your area just to verify your claim. You may want to ask any of your neighbors on their power consumption especially if they have an electric water heater. A factor in electric water heater usage is the cold water temperature. My brother's cabin home in VT the well water must be 45 degrees where here in Florida it's about 75 degrees. It takes a lot of energy to heat water.

The water is not overly hot, so the thermostat is not likely to be the culprit, and while we do have well water, here in Maryland the water temperature is not that cold. In our prior home in Connecticut, we also had (colder) well water and a 40 gallon electric heater in a larger home, but our consumption was lower. It is an 80 gallon water heater, so that could be part of the problem. Also, if sediment has built up around the heating elements I would assume it would be less efficient. We added a water softener when we moved in; prior to that there was none.

If metering the water heater doesn't point me to the solution, then I will request that the utility company change the meter. That said, it's a mechanical meter and I don't think I've ever heard of one running fast. We do receive statements comparing our usage to our neighbors in similar sized homes, and we are consistently using significantly more electricity.

 

[Jadnashua]

Does your hot water line(s) run underneath the house? Are there any spots in the house, if you have pets, that they seem to like to sleep at? Do you notice any spots where the floor seems warm? Are there any areas outside of the house that seem greener than others?

The reason I ask this is that there might be a hot water line leak underneath the house, and with a larger enough water heater, and a not huge leak, you might not notice a loss of capacity in the WH. Do you notice that the WH is heating all of the time? The only way that could happen and not superheat the water is if there's a leak, and cold water is constantly being added. WIth a well, does the pump run on a regular basis, even when you're not using water in the house? The combination of the pump running often and the energy from trying to reheat the water could be the source of your energy consumption. Regarding the well and the pump, if you shut off the pump, don't use water, does the pressure drop? If there's a leaking check valve, the pump would need to turn on more often to keep the pressure up in the home. If it got too bad, you wouldn't have any pressure unless the pump were always (or nearly always) running. That would also cause your electric bill to be high.

 

[SAS]

Does your hot water line(s) run underneath the house? Are there any spots in the house, if you have pets, that they seem to like to sleep at? Do you notice any spots where the floor seems warm? Are there any areas outside of the house that seem greener than others?

The reason I ask this is that there might be a hot water line leak underneath the house, and with a larger enough water heater, and a not huge leak, you might not notice a loss of capacity in the WH. Do you notice that the WH is heating all of the time? The only way that could happen and not superheat the water is if there's a leak, and cold water is constantly being added. WIth a well, does the pump run on a regular basis, even when you're not using water in the house? The combination of the pump running often and the energy from trying to reheat the water could be the source of your energy consumption. Regarding the well and the pump, if you shut off the pump, don't use water, does the pressure drop? If there's a leaking check valve, the pump would need to turn on more often to keep the pressure up in the home. If it got too bad, you wouldn't have any pressure unless the pump were always (or nearly always) running. That would also cause your electric bill to be high.

Good suggestions, but for the most part I don't see any of them fitting the problem. There are no underground water pipes, and the well pump and pressure tank are working as they should. I know that because several months ago I had to replace the pressure tank. One thing I do wonder about is the hot water recirculation system. Sometimes I have trouble getting cold water from the kitchen faucet. It's a single handle model and I've replaced the cartridge, but sometimes it still happens. I don't have the problem in other plumbing fixtures.
My plan is to install a meter this weekend to see whether the hot water heater is indeed the problem. If not, I'll have to move on to some other potential cause of the problem. If so, the only thing other than the heater itself that I can think of is the hot water recirculation system. I guess I can just turn off the pump and close the valve between the pump and the hot water heater to see if that is somehow causing a problem.

 

[WorthFlorida]

I asked if you have any electric heating elements in your AC air handler. You also mentioned you have a heat pump. Take readings with your clamp meter at the breaker panel with the unit not running by the thermostat setting. Check both breakers for the compressor and air handler.

At my last home in Palm Beach Cty about ten years ago I had a leak in the A/C lines that ran under the slab and up an interior wall to the air handler. The a/c is used almost everyday in South Florida. After the lines were replaced my electric usage dropped for each of the next 12 months. The bill would have the usage used of the same month as the previous year. As luck would have it after 12 months the electric meter was changed from analog to digital. The usage dropped again for the next 12 months. I could only conclude that old meter was giving higher readings or the the digital meter was reading less.

 

[PorcelainVacation]

Do you have a sump pump? Check that too.

 

[SAS]

I have part of the answer, but I'm not sure that it explains everything. Over the course of 1 day, the hot water heater used 20 kwh. According to the energy label, I should expect it to use 13.2. I'm not sure how they calculate that usage, but we are just 2 adults who do not use much hot water. No filled bathtubs, short showers, etc. I would guess that those Dept. of Energy estimates are based upon a family of 4.

So I'm using about 50% more electricity for hot water than I would expect. Still, even if I only used 13.2 kwh for hot water that would not dramatically lower my monthly usage. If I use 7 kwh fewer per day, I will still be using over 2250 kwh per month. Today I disconnected the hot water recirculation pump and closed the valve to see how much extra hot water heater usage it requires. I've also found a supplier to provide electricity at a lower rate, so the bill should become more reasonable, but I'm still wondering about that meter. I think my next test will be to turn off everything but the hot water heater and compare the outdoor meter to the one I've installed.

Any other suggestions?