The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Topic Options
Rate This Topic
#6646 - 01/09/02 10:25 AM Load Balance & cost saving question
static Offline
Member
Registered: 01/09/02
Posts: 12
Loc: Detroit,MI, USA
Hello,

This is my first time posting, but I have been reading the messages here for some time. I don't do this for a living or anything, just like to learn all I can.

In reading some messages on another message board in the links area, I read a message where a person talked about balancing his loads between phases. He said that if leg 1 was pulling 30 amps and leg 2 was pulling 40 amps, the meter would record the highest usage at 40 amps but if you were to balance the loads, the meter would record a lower overall usage. The question I have, is this the case? It seems as if the power company would want to meter all usage, not just peak.

Thanks,
Static
Top
Work Gear for Electricians and the Trades
#6647 - 01/09/02 10:39 AM Re: Load Balance & cost saving question
George Corron Offline
Member
Registered: 05/16/01
Posts: 728
Loc: Lorton, Va USA
Static,
The power companies use a Watt-hour meter. They will monitor (and therefore charge for) watts used period. You are correct in assuming that load balancing has nothing to do with PoCo charges. It does have to do with conductor heating, neutral sizing, etc.. Nope, you're correct.
Top
#6648 - 01/09/02 11:08 AM Re: Load Balance & cost saving question
Anonymous
Unregistered

Static,

George is correct in saying that you pay for all power used. There are however some utilities that will charge a penalty based on the peak usage during the billing period. Generally the meter will record the largest usage of power and the PoCo will charge based on that. This does not affect residential charges, however this does affect large scale commercial and industrial users. This encourages the consumer to balance their load since the highest usage is taken on a per leg basis. You still pay for all power used, but by balancing the load evenly, the penalty can be brought down dramatically. Again I only know of this being used in large commercial and industrial areas.
Top
#6649 - 01/09/02 11:30 AM Re: Load Balance & cost saving question
static Offline
Member
Registered: 01/09/02
Posts: 12
Loc: Detroit,MI, USA
When the drop comes to my house and goes to the meter, how does it connect? If it only has 2 contacts? Just based on that I don't see how the meter would "Know" how to charge different for each leg. It sounds like someone was wishful thinking to me.

What I wish they did in my area was to have a dual meter to charge for peak and off peak, I could easily wait for night to do wash and such. As it stands now they just bill .0824 for the first 629 KWH and then .0965 after that. I have been working on lowering my usage as best I can with compact flourescents, so when I interested when I read the story of the phase thing.

Thanks for your responses.

Static
Top
#6650 - 01/09/02 02:29 PM Re: Load Balance & cost saving question
WARREN1 Offline
Member
Registered: 05/09/01
Posts: 184
Loc: Greenville, SC, USA
Static
The lighting in your house is the smallest user of electricity you have in any building. Your HVAC, clothes dryer, refrigerator, and freezers are your biggest users. Most people don't ever clean out the dust accumulations under their refrigerator, causing it to work harder to keep things cool. Yes, using compact fluorescent will help a little, but you can save more by making your big users use less. A clothes dryer sucking in outside cold air in the wintertime is not the most efficient way. Allowing it to dump warm out from inside your house is not the most efficient way. So, take a look at the big users first.
Good luck.
Top
#6651 - 01/09/02 05:11 PM Re: Load Balance & cost saving question
Anonymous
Unregistered

Static,

Residential metering and commercial/industrial metering are very much different from each other, but yet they rely on the same thing. The older gear-type meters (the ones with the nifty spinning wheel in the center) were unable to record a peak reading during a given amount of time. However with the evolution of the digital meter and the use of "pulses" by the PoCo to track usage, it has become very simple to look at the power consumption at any given point in time. The 3-phase meter does not see the full load current and works off of properly sized current transformers (or CT's generally 200:5, 400:5, 600:6, etc.) and voltage leads brought down from the weather head off the main lines in. Since the meters dont see the full load current, their interal electronics can be more geared toward bells and whistles instead of just straight metering. Allowing for the reading of peak loads. Again this I have only seen in commercial/industrial settings. Residential metering uses a very simple form of the kilowatt/hour meter. This type of meter is designed to see the full load current of the service and essentially "bridges" the gap between your electrical system and the PoCo's supply. Your power flows through your meter and is recorded. If you ever have a chance look inside a wired meter socket on a house. You will see four contacts, two on top and two on the bottom. Generally the top two contacts are the legs from the PoCo that come down from the weather head and the bottom two contacts are the legs that go to your electrical panel. When the meter is pushed into place, the four prongs on the back of the meter line up with the contacts in the base and they circuit it completed through the meter. Like I said before, its the bridge. The meter uses the voltage and current from each leg and "adds" them internally through induced currents to get your total kilowatt/hour usage. Should you lose a phase for some reason, the meter will still read. There is some pretty fun stuff you can do with residential meters to help understand some concepts of metering, but I go into them here. I hope this helps. If you have any more questions please ask.

[This message has been edited by bigbluewirenut (edited 01-09-2002).]
Top
#6652 - 01/09/02 08:32 PM Re: Load Balance & cost saving question
static Offline
Member
Registered: 01/09/02
Posts: 12
Loc: Detroit,MI, USA
I do realize that the lights are a small part, but they are about the only thing that I can do to cut down. I have 3 50 gallon fish tanks in a built in setup, a freezer and 2 refrigerators, 2 computers that all run 24 hours a day. I look at them as things that I am not willing to change. I do have timers on my lights for the tanks, I keep the coils clean on the freezer and fridges and while I could turn off the computers, I keep them running to practice training from work (server stuff).
I looked at what other things I could do and found that using 15 watt CF's in all the cans in the basement, and in the bedroom fixtures as well as the track lighting has helped. I am not one to leave anything on that I am not using but I have 4 kids so it is always a challenge. I average $120 a month most of time and about $250 if I have to run the window ac's (Getting central this spring) I don't think that is all that bad with everything I have running.

Thanks to everyone for answering my questions, now I understand how the meter works and why the balanced load thing will not save on the bill. Just another too good to be true thing.

Static
Top

Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box

Recent Posts
Looking for older post
by sparkyinak
Today at 12:27 AM
License exam
by TRUE POWER
Yesterday at 11:33 PM
Members: Non-Members: Did you know?
by Admin
Yesterday at 02:34 PM
Safety at heights?
by HotLine1
01/21/17 08:51 PM
International Wire Colour Codes
by Texas_Ranger
01/21/17 03:29 PM

Who's Online
0 registered (), 76 Guests and 8 Spiders online.
Key: Admin, Global Mod, Mod
New in the Gallery:
Desk-mounted "power-board"
Top Posters
gfretwell 9066
Trumpy 8560
pauluk 7693
HotLine1 6833
sparky 5545
Member Spotlight
Tom
Tom
Member Since: 01/01/01
Posts: 1069

ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals