HOM20M100C panel - use of tandem breakers?

Discussion in 'Electrical Forum discussion & Blog' started by Pickngrin, May 6, 2010.

  1. Pickngrin

    Pickngrin New Member

    Messages:
    54
    Location:
    Massachusetts
    I have a Homeline HOM20M100C panel in my house and wanted to add a circuit in the garage, but have no open breaker slots. I just read online that this panel does not allow tandem breakers, yet there are currently 2 tandem breakers in my panel (they were there before I bought the house). Are these tandem breakers somehow jerry-rigged, or does this panel in fact allow tandems?

    Thanks
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,486
    Location:
    Cave Creek, Arizona
    They might have found a compatible tandem which did fit the panel, or might have modified the breaker or mounting so it could be attached. No way to tell without seeing YOUR panel and YOUR tandem breaker.
  3. drick

    drick In the Trades

    Messages:
    392
    Just because it fits doesn't mean you should use it.

    Open the door on your breaker panel and look at the label. It will list the breakers that can be used in that panel. To determine if a breaker can be used in the panel look at the breaker and locate a label indicating its type. Then look and see if it is listed on the label on the panel door. If it is you should be ok. You can also check the max current interrupt rating for the breaker. It will be listed on the panel door next to the breaker type and also marked (possibly stamped into) the breaker itself. Breakers are rated in thousands of amps. Whatever is indicated on the panel door and on the breaker should be the same.

    If the 'tandem breaker' is not listed you should not use it.

    If the panel is full consider upgrading it or installing a subpanel in the basement as well.

    -rick
  4. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    Possibly. There is a rejection thingy that doen't allow the breaker to plug into a "normal" bus. The bus has to be notched in the middle to accept tandems. They could also be CL breakers listed for replacement use only. There is no rejection thingy in those but they're still not "legal" in this panel.

    One solution would be to find two circuits that are lightly loaded and put them on one breaker, freeing up one.
  5. Pickngrin

    Pickngrin New Member

    Messages:
    54
    Location:
    Massachusetts
    Thanks for the responses. I will double check the info on the panel, but I am surprised that 1 of the 2 tandem breakers was installed by a licensed electrician when we had our hot water heater replaced a couple of years ago. What made matters worse was that days after he replaced the HWH, my wife went to turn on our wall air conditioner for the first time of the season. It didn't turn on, so I started doing some sleuthing. It's on a 240V line, and it didn't take me long to realize that the electrician replaced a 240V breaker with that tandem 120V breaker. And he had the balls to charge me for a service call to come back to fix his mistake. Er, sorry for ranting there, a bit off topic.
    I am considering having the panel upgraded or, as suggested, adding a subpanel, if we will be staying in this house.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,486
    Location:
    Cave Creek, Arizona
    A tandem 120v breaker would only have taken HALF the space of the 240 so what did he do with the extra slot? An "electrician" would have know better than to do what you say was done, so either he was NOT an electrician, or he was a very poor one.
  7. Pickngrin

    Pickngrin New Member

    Messages:
    54
    Location:
    Massachusetts
    Oh, I didn't realize that. All I know was that after the electrician left, our 240V receptacle for the wall a/c unit no longer carried 240V. Perhaps my explanation for how it happened was wrong.
    Our plumber (who is a very competent, licensed plumber) recommended that electrician.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,486
    Location:
    Cave Creek, Arizona
    I also do not know exactly what happened, and cannot from your description. HOW it was cured might be beneficial. Using your original diagnosis, about the only logical conclusion would be that he removed a 240v double breaker, installed a tandem AND a standard single pole, then connected both wires for the receptacle, to the tandem breaker. IF that is what happened, my original comment still stands, that he "was not an electrician".
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