User Tag List

Page 1 of 2 1 2 LastLast
Results 1 to 10 of 20

Thread: Fire chief needs electrical advice

  1. #1
    Join Date
    Nov 2010
    Location
    indiana
    Posts
    3
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Exclamation Fire chief needs electrical advice

    I was hired to replace all the lighting in a fire station with high efficiency lighting and motion detectors. The fire chief explained to me that the electric bill was averaging $700 a month and hoped upgrading to high efficiency fixtures an bulbs along with motion sensors would lower the bill. I thought the $700 bill per month sounded very high considering they mostly just watch tv to pass away the down time. The chief believed the lighting was the main culprit considering the lights were left on more than turned off. Now it has been 3 months and the chief gave me an update. He said the bill had gone down slightly but something else must be driving the bill sky high. I suspected the bill would not drop dramatically but would like to solve this puzzle and plan to offer some free consulting to the chief to help him figure out the problem. (yes the chiefs under the gun with a shrinking budget)

    Besides a tv that pretty much never gets turned off, the rest of the basics like a microwave, electric stove, 2 fridges, ect,, most of whats being used would be comparable to a residential home .

    Here is what I discovered upon further investigating and need some advice.

    The service is 240 3 phase. A phase and B phase feed a couple sub panels which supply electric to all the 120/240 devices in the building. the 240v 3 phase only feeds an air pack system (to refill oxygen tanks) and 3 phase also feeds a 240v commercial sized dryer. The chief told me that the air pack system is only used 2 or 3 times a month and the dryer may be used by a handfull of fireman who dry their fireproof gear after a fire and a few of the guys wash their work uniforms at the station while the majority take their laundry home to wash and dry. (so 3 phase loads are rare)

    SO I know this is a lot of ambiguous information but in a nutshell the $700 electric bill a month seems like it's twice as high as it should be. This is a small town fire station btw. 6 to 8 fireman per 24 hour shift.

    I've taken Mike Holts 14 week instructional class (6 weeks electron theory, 8 weeks preparing for master exam) and I have just bought his dvd series. I'm still learning , I come to this forum often to help me make sense of things that haven't clicked yet despite the excellent class I took and the dvds I watch. Unbalanced loads still baffle me. I think the A and B phase electrons are canceling each other out on the 240 single phase loads but the C phase without a load confuses me. I think those electrons return to the source via the neutral.... or with 0 amps , since there is no load ,maybe the service acts as a single phase system 180 degrees (when zero amps on c phase) ???? . I'm unsure how this effects the kwh or does it? Does this cause a power factor issue? Is the service acting as an open delta 95% of the time???

    anyway.......
    I plan to return and do a load calculation which would give me numbers to play with and I know 99% of you reading this would like some numbers now. (I've read a lot of threads on this forum lol).

    Here is my question.

    Would the manner in which the main service panel has been split, using 2 phases to supply virtually all the power being used daily..... And then the 3 phase just powering rarely used devices .... be the prime suspect here for the high bill. I obviously recognize that the service is very unbalanced and I would have never split it up like it is, but -
    :confused:what effect would you expect that this setup would play on the electric bill? or would it :-?

    Just asking for general advice right now without providing you guys with numbers to crunch at this time.

    Best guesses and theories will be appreciated!

    what say you?


    Thanks
    Ben

  2. #2
    Join Date
    Nov 2010
    Location
    indiana
    Posts
    3
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    this my first time posting on this forum... thanks for your time.

  3. #3
    Join Date
    Jan 2009
    Location
    3 Hr 2 Min from Winged Horses
    Posts
    15,966
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I would look for a high impedence fault like a WH going to ground for example.
    "Electricity is really just organized lightning." George Carlin


    Derek

  4. #4
    Join Date
    Jan 2008
    Posts
    9,784
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by gr8benwa View Post
    Would the manner in which the main service panel has been split, using 2 phases to supply virtually all the power being used daily..... And then the 3 phase just powering rarely used devices .... be the prime suspect here for the high bill.
    No.

    I suspect it is the cooking, washing, external lighting, etc that goes on.

    To verify this, take your ammeter into the panel and read each circuit. I suspect you will find very little load if no one is doing anything. A building running 24x7 might use more than you think as there would just tend to be more activity than a typical house.

    Of course, it might use less than I think. I'll see if I can find some usage in some data I have.
    BB+/BB=?

  5. #5
    Join Date
    Jan 2009
    Location
    Massachusetts
    Posts
    265
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I'd think it unlikely that an unbalanced load as you describe would cause the high bill. If the same load was completely balanced the maximum current on the conductors would be less than in an unbalanced condition. An unbalanced condition may dissipate slightly more power in the transformer and service conductors, but they would have to be sized incorrectly for it to make any substantial difference. Furthermore, only the conductors on the load side of the meter would contribute - the rest would be loss only the POCO would see (though extra voltage drop could be observed). The biggest reason I see to be concerned with balancing the load is when the use starts to approach the current limits of the service - you can get about 3x the rated power if it is perfectly balanced vs. completely unbalanced. At least that is how I understand it.

    So bottom line, I agree with the other posts in that it is most likely an issue with unexpected (but not necessarily improper) load.

  6. #6
    Join Date
    Aug 2004
    Location
    Northern illinois
    Posts
    17,453
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    A fire station is a 24/7 operation as someone else mentioned. I would expect to see a lot more use there than a "normal" installation.

    A lot of people are shocked at how much they are paying for stuff that is not even in use. Wall warts and other things that are plugged in all the time but not actually in use can suck a lot of juice.

    Spend a few hours poking around and doing some measurements and you will no doubt find where the energy is being used, and maybe come up with some ways to reduce that energy usage. But maybe not.
    Bob

  7. #7
    Join Date
    Nov 2003
    Location
    Roanoke, VA.
    Posts
    4,849
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by gr8benwa View Post
    The service is 240 3 phase. A phase and B phase feed a couple sub panels which supply electric to all the 120/240 devices in the building. the 240v 3 phase only feeds an air pack system (to refill oxygen tanks) and 3 phase also feeds a 240v commercial sized dryer. The chief told me that the air pack system is only used 2 or 3 times a month and the dryer may be used by a handfull of fireman who dry their fireproof gear after a fire and a few of the guys wash their work uniforms at the station while the majority take their laundry home to wash and dry. (so 3 phase loads are rare)
    Be careful! Sounds like you may have a high leg in there.
    By code it should be identified with orange coloring and on B phase but some POCO's want it on C phase.
    Don't move anything around until you verify the voltage you have.

  8. #8
    Join Date
    Jul 2005
    Location
    Gainesville, Florida
    Posts
    1,054
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    $$$ to save $$$

    you need to investigate every circuit.
    3 rules of thermo dynamics; can't win, can't loose, cant get out of the game.
    Meaning same amount of energy to power the device no mater what you do.

    Look for old or going bad motors or water heaters. They will be the most obvious.
    Get in touch with your local utility. They always have some great ideas on how to conserve energy.
    Don't panic,tell the cheif to move the electric bill or a portion there of to a different column in the books for image or advertising, or security. Room motion sensors work ok but do you want a vacant looking building when nobody is there?
    Changing out the lamps from incandescent to florescent is a really good start. Instant water heaters are a real saver too, I have 3 teenagers and it saved me $100 a month. With the 3 phase you can get a real deal. Turn down the thermostat and seal up the windows or better yet replace them with low e ones if you have the budget. Caulk and seal the holes and insulate. All of this is going to take money. Its available if you can get the grant money. Good luck.

  9. #9
    Join Date
    Jan 2009
    Location
    3 Hr 2 Min from Winged Horses
    Posts
    15,966
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by gr8benwa View Post
    The fire chief explained to me that the electric bill was averaging $700 a month sky high.
    Quote Originally Posted by jumper View Post
    I would look for a high impedence fault like a WH going to ground for example.
    Whoops! Aw phooey, I missed the "averaging" part.:mad:

    I thought the bill went up 700$ a month. I focused on the word "high".
    "Electricity is really just organized lightning." George Carlin


    Derek

  10. #10
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    7,880
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    101123-0919 EST

    gr8benwa:

    Suitable instrumentation would help you analyze the problem.

    Ideally this would be some sort of power monitor with recording capability. Just using a single channel recording ammeter would provide some help.

    Assume the cost of power is $0.10/KWH. Then $700/month is about 7000 KWH/month or about 225 KWH/day or about 10 KW continuous load.

    The dryer and any electric water heater are likely high usage. A new TV might be in the range of 100 W or 2.4 KWH/day. As stated above use an ammeter as a simple test tool. Turn off all obvious loads, and check the current in each phase. Note whether any large loads are on at this time. You can probably turn off most large loads with the breaker without the load caring. You have to probe for what is using large amounts of power for long times. However, many small loads that are on for a long time can add up. For example: 200 W 24/7 would be about 0.2*24*31 = 150 KWH/month.

    Always check my math. I make mistakes that I do not see many times.

    .

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •