Low voltage & mega kilowatt usage

sdswcs

Does low voltage (107v) coming in from an electric line have any bearing on the amount of kilowatts being pulled and sent through to the meter?


My problem is I've got low voltage coming in (107 - 114v), but I'm running about 7200 kilowatts through the meter! So far, everything has checked out at the pole, have unplugged everything inside and ran a reading on every appliance, etc., nothing out of the ordinary. Average kilowatt usage should be 850 - 1000/mo. Thought maybe the underground line from the box to inside had been damaged when pulling through conduit, so ran a new line on top of ground from the box to inside, no change.

I assumed if you had low voltage coming in, your using more kilowatts because it's taking more energy to run things.

Any theories?

jerryh3

Where are you measuring the voltage? Is the voltage the same on both phases?

AllanJ

I don't know the behavior of different kinds of motors, light, etc. but some devices draw more amperes when supplied with less voltage and some don't. .

Many motors do draw more watts when given abnormally low voltage which is why a lot of folks have motor overheating problems during a brownout or with voltage drop from such things as too thin extension cords. But not such an excess to cause a 1000 KWH bill to suddenly become 7000 KWH the next month.

Your low voltage can be due to a variety of causes, an overloaded transformer or incorrectly set voltage regulator on the utility pole are two.

Do you have an electric water heater and a leak in a hot water line? This can run up your electric bill tremendously, just because the heater is "on" a lot more. You won't see a difference by measuring current for a minute or two every so often.

sdswcs

Jerry ~~ No, the volts are not the same they vary between 1 & 2 v. We've measured from the meter and inside the house.

Allan ~~ No, we don't have an electric water heater, they are propane.

The electric company has been out and has admitted that they are having trouble at the sub-station with the low voltage. When asked the question whether the low voltage has anything to do with the amount of kilowatts we're using, some of them say it would, and some say it wouldn't. I need a definitive answer from someone as to whether it would have any affect on the kilowatts we're being charged for.

The electric co. has put a special meter on the box that measures everything 24/7, like a black box.

We've lived here for 14 years, and our electric has been extremely high the entire time, but it appears to be getting worse. Wrote a letter to the PUCO a few years ago, sent the electric co. out and they checked the meter and the fuse on top of the transformer and said everything was ok and that it had to be on our end, and they weren't very happy about being there in the
first place!

If the low voltage doesn't have anything to do with the amount of kilowatts we're using, does anyone have any suggestions as to where else to start looking?

Thanks for all your help, I really appreciate it!

BigJimmy

Good point. Your load could be somewhat imbalanced between phases.

On the other hand, I believe (and my memory may be a bit fuzzy here) that the POCO's guarantee a voltage at the service point of +/-10% of nominal. Assuming a base voltage of 120VAC (different utilities may define differently), this puts you on the ragged edge of acceptable level. You can always contact the POCO and explain the circumstances which may result in a call-out to check it. There may be an issue where for instance the secondary voltage on their local distribution system is low due to excessive load growth without an increase in distribution transformer sizing/installation on their part. BUT-as was said (or implied) before, you should check both your incoming lines to neutral at the breaker lugs. Your "low voltage" condition could be simply a result of unbalanced load, i.e. too much on one incoming line w.r.t. the other.

Now, regarding power usage, I have to mention that 7200KW equates to 7.2MW (mega-watts). Unless you have an entirely different residence than I'm used to, I doubt you're consuming anywhere near this (as a frame of reference, the average MW load of a certain Big Ten University is about 40MW. Spartans?).

As AllanJ put it, constant HP motors will tend to draw more current as the voltage drops. That's why low voltage is typically bad for motors (as he mentioned in a brown out situation) as the current increases and can damage the windings. Your table lamp? It will just produce less light output.

Anyway, take a voltmeter and check L1 and L2 to neutral separately. If both are reading low then either a.) you are drawing an extreme amount of current which is causing a significant voltage drop in the service drop/lateral or, b.) the POCO's secondary voltage is low (due to excessive loading, bad voltage regulating devices, etc.).

Q: What changed to make you measure the voltage? Or were you just curious?

If your electric bill suddenly surged, it means simply load has increased (as others have mentioned).

Jimmy

__________________
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves,"You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." - George Carlin

elkangorito

As per Australian regulations, the acceptable supply voltage variation is +10% & -6%. It could be different in the US. Perhaps the NEC could shed some light on this?

In the meantime, your KWh meter will calculate the power used disregarding any small voltage variation, although these meters will have upper & lower acceptable operating limits (voltage & Power Factor etc). I would suggest that your KWh meter is not being affected by this voltage variation.

You claim 7 200 kW "through the meter". Over what period of time did this consumption occur? 1 month? 6 months? 12 months? Also, I think you mean "7 200 kilowatt hours".

You also may like to check that your equipment/appliances are drawing the correct current. This can be done by using a clamp meter & then doing some "correct" calculations.

The only other thing that could be a problem is the KWh meter. What type is it? Is it electronic or induction disc (spinning disc)?

__________________
Switchboard design engineer & Licensed Electrician (Australia).

nacko

go back through your power company bills for the last couple years and check your usage (kilowatt hours) for the different months of the year. this should help you determine if something is wrong or not. if your power usage (not just your billed amount) is actually increasing, you should be able to determine approx. when it started happening. this might give you a clue as to why (did you install a new appliance, do some remodeling, did the power company redo power lines, was a neighbor's house under construction, any new fences put in, etc) with a little detective work you might be able to figure out if anything is actually happening, and if so why.

hope this helps

sdswcs

Thanks everyone for your reply's.

Yes, we are using 7,200 kw hours. I just received a letter from the electric co. today showing that the meter checked out ok.

The electric has been this way since we've been here (14 years), so it's going to be hard to compare.

The unanswered question is, if we've been receiving low voltage since we've been here, is the low voltage what is causing our high bill? Does the low voltage put a drag on the system?

perpetual98

Check to see if your neighbors have an indoor pot-farm and somehow plugged into your house.

NateHanson

You've been paying for 7200kwh each MONTH for 14 years? That's like $1000/month! Your meter must spin so fast it's dizzying! Short of a pot-farm or a reef-tank, I can't imagine what's drawing all that power, but I'd sure as heck figure it out THIS month!

Good luck

sdswcs

Here in the winter, that is about the average of what are meter is at. The lowest it's been in the last 12 months has been 3480, last Feb it was 8520!
I would be elated with 2000/month!

The electric co. is probably not going to go too far out of their way to help and so far, everything that's been checked on "our" side of the pole checks out ok. We are on a single phase, but we are the only one on the transformer coming into our pole. We asked the electric co. to replace the transformer, but they swear there's nothing wrong with it.

jerryh3

Can you give give a little information about the house and the power loads it has.

LawnGuyLandSparky

If you haven't changed anything on your end, and your electric bill suddenly spikes (usage-wise, not cost wise as utility rates often change, and in only one direction) some common but not obvious causes are:

-Your refrigerator is stuck in defrost mode, or has a worn, leaking seal, or both. Or it's light is stuck on.

-A sump pump discharge isn't working and it's now running 24/7

-Your daughter has embraced "hair straightening" with a 1400 watt iron 1-2 hours a day

-Someone has tapped into your power.

-You're leaving the computer on 24/7

LawnGuyLandSparky

Do you have a heat pump?

perpetual98

I keep our computer on 24/7, but am thinking about stopping that habit. We're looking for ways to start shaving money, and while it's only about $1 and change a day to run it constantly, it's still around $35 a month. Then again our 500W power supply (if it's even that big, our PC is several years old) isn't using 500W of power at idle, it's still using some. I'd have to put a Kill-A-Watt meter on it to check.