Electricity Cost Calculation

Discussion in 'Electrical Forum discussion & Blog' started by pipehacker, Jun 10, 2011.

  1. pipehacker

    pipehacker New Member

    Messages:
    191
    Location:
    Iowa
    We have a strange situation. We own a rental duplex. Each unit has separate meters and pays its own electricity and other utilities. The duplex has a detached duplex garage, with one tenant having one stall and the other tenant having two stalls. When the duplex and garage were built about 15 years ago (before we owned them) all the garage's electical wiring was apparently connected to one of the duplex units. The tenant in this unit is now concerned that he has to pay for the other tenant's operation of the garage door opener, interior garage light, etc. I told him that any cost to him would be miniscule. How could I calculate what the actual cost to him is? Any thoughts?
  2. Dana

    Dana In the trades

    Messages:
    2,785
    Location:
    01609
    You could kill all the other breakers in his panel, turn all the lights on, and have some kid open & close the garage door as much as he can for an hour and measure it on the meter or something. :)

    Or you can install only high-efficiency lighting and put an occupancy-sensor switch on it. The biggest cost to him would be if someone left the lights on, since the motor is probably less than 200 watts, and only runs a minute or two per day. 200 watts is 0.2 kw, 2 minutes is 0.033 hours, so...

    0.2 kilowatts x 0.033 hours is 0.007 kwh/day x 365= 2.5kwh/year

    A couple of 40 watt lights is 0.08 kilowatts, but if you left them on for a whole day (24 hours), that's about 1.9 kwh per DAY.

    With an occupancy sensor or timer switch that can't happen, and odds are it would add up to less than 1 hour per day, so it would be at most the power rating of the lights, x 365 days/year.

    Or you could just comp him a 6-pack once or twice a year for being such a good sport. ;-)

    If he insists on the penny-accounting, look up the specs for the actual power draw of the garage door opener, measure how many seconds it take to both open and close it, take a reasonable stab on the average daily open/close, and add it up for a year in hours x kilowatts. Do a similar estimate on garage light use & power. It's not nothing, but it's probably less that the value of the time it takes to calculate it.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I don't know what kind of laws you have up there. Around here, if the one tenant complained to the landlord that someone else's usage was on his meter, you the landlord would be in deep kim chi. Also, the regulations of the public utilities commission in many places would not allow you to "estimate" the usage and charge the tenants accordingly. SO, the city would force you to separate the uses , or pay both bills yourself and simply increase the rent by an appropriate amount guestimated, and the rent contract would say "electricity included".

    Now, the usage in question is probably minimal....dollars per month, but not tens of dollars, probably, unless one guy is using a lot of lights, power tools, etc. SO, to keep peace in the family, you could make the guy who gets the bill an offer he can't refuse. Give him a Starbucks card, or whatever!!
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,817
    Location:
    New England
    There are some plug-in devices (similar to a surge suppressor) that measure the power consumption of the items plugged into it. I think they also allow you to insert the local cost per Kw, and then you can just read out the actual cost of the stuff, or at least a good estimate. This only works on stuff with a plug that can be plugged into the device, though.
  5. johan4551

    johan4551 New Member

    Messages:
    1
    Location:
    Delhi, India
    Hello everyone
    LOTW I have an idea which you can apply and may be helping you in calculating electricity bill. Try to switch off all the electrical appliances of your home and monitor the reading of your tenant meter and ask your tenant to switch off all the appliances and then open and close your garage door so that you can get the reading of electrical unit consume by that door. In this way you can calculate the reading.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,817
    Location:
    New England
    The label on the opener will have a (max) current draw. Time how long it takes to open. Do the same for closing (they may not be the same). Estimate how many times a day it typically happens...take that and using your electrical rate, figure out an approximation.

    But, if you use one of the devices I mentioned, and input your local rates, it will read out what the cost total is. It should be fairly accurate.
  7. DonL

    DonL Jack of all trades

    Messages:
    3,812
    Location:
    Houston, TX
  8. pipehacker

    pipehacker New Member

    Messages:
    191
    Location:
    Iowa
    After rigorous calculations it has been determined that the cost of the electricity is precisely equal to the cost of one case of Newcastle Nut Brown Ale minus the six bottles I was required to sample.
  9. BobL43

    BobL43 DIY Senior Member

    Messages:
    1,786
    Location:
    Long Island, NY
    I've got one of those devices, the older one that does not store the readings and loses it in a power failure; but even the one I have is indeed a very nice tool the Kill A what (spelled wrong here of course) for anybody that thinks they pay a lot for electricity, I think I'll make them feel better by posting a copy of my electric bill here. We have LIPA here on Long Island, NY, and we pay through the nose.
  10. DonL

    DonL Jack of all trades

    Messages:
    3,812
    Location:
    Houston, TX
    The new one is worth the price, It is only a few dollars more, now.

    It would be nice if it had back lighting on the display, but it works very well and calculates the cost for you.

    And LOTW, that is nice, sounds like you found a solution, that benefits all.


    Have a great Day


    DonL
  11. BobL43

    BobL43 DIY Senior Member

    Messages:
    1,786
    Location:
    Long Island, NY
    I like your new Avatar Don!
Similar Threads: Electricity Cost
Forum Title Date
Electrical Forum discussion & Blog Question about feeding electricity to house Nov 20, 2013
Electrical Forum discussion & Blog Make metal glow with electricity Feb 26, 2013
Electrical Forum discussion & Blog Electricity connection to Kohler K-1733 steam generator Sep 18, 2011
Electrical Forum discussion & Blog static electricity with outdoor deck Jul 31, 2011
Electrical Forum discussion & Blog Electricity power drained Jan 10, 2011

Share This Page