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  1. #1
    Join Date
    Jan 2014

    Default exterior disconnect for AC

    Can someone please try to explain what they think is going on here. Electrical is not my strong suit and I would like a second opinion. Thanks
    The 15 amp breaker in the first box is feeding the second box which is for a Mitsubishi condenser.

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  2. #2
    Join Date
    Mar 2007
    Ormond Beach, Florida

    Default Re: exterior disconnect for AC

    Quote Originally Posted by Wayne Edwards View Post
    The 15 amp breaker in the first box is feeding the second box which is for a Mitsubishi condenser.
    The first box I presume you mean is the one with the double pole breaker being fed with 120 volts and using one side of the breaker, with the 120 volts using black as the ungrounded (hot) conductor, red as the grounded (supposed to be white, NOT red) conductor, and what looks to be blue due to the flash but is probably actually green as the grounding conductor (equipment ground) - except that in the other photo, there is a difference between the green conductor and the blue conductor, so the blue conductor in the first photo may actually be blue?).

    The first issue is the red color used for the grounded conductor (should be white NOT red).

    The second issue is the blue color used for the grounding conductor (should be green or bare NOT blue).

    The other photo shows the black grounded (hot) conductor coming in at the bottom left, with the red conductor and the blue conductor, and what looks to be another supply coming in to the right of it - the other supply has red, black, white, and bare ground.

    Are you sure that the 15 amp double pole breaker (I don't see the 15 amp rating, but you were there) is the supply in?

    From the photos, this I what I suspect:
    - The red, black, white, and bare ground is the supply in (240 volts).
    - That 240 volt supply in feeds a pull out disconnect (which has been pulled out or is missing).
    - That goes behind, and does not feed, the GFCI device above it and goes to the terminal block in the upper left (looks like it may be a key-type disconnect?).
    - The white goes to L2 (N) so that looks correct.
    - The black goes to L3 and is jumpered to L1 - I suspect that the black should go to L1 and (if necessary) be jumpered to L3 as L1 is the terminal which feeds through to T1 (T3 is not used, so they had to jumper it over to L1 to get power to T1). T3 is not being used.
    - The red goes to L4 and is not being used (nothing on T4, so only 120 volts is being used).
    - I can see conductors going to/from the GFCI device, but cannot see where they are connected (possibly coming off the back side of that device where they are not visible).
    - The black ungrounded (hot) conductor from T1 goes to the 15 amp breaker.
    - The red-but-should-be-white grounded conductor comes off T2(N).
    - The black, red-but-should-be-white, and blue-but-should-be-green/bare goes to ... the disconnect in the other photo?

    Question: What goes to/from the exterior disconnect?

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( )

  3. #3
    Join Date
    Mar 2012
    Lansdale, PA

    Default Re: exterior disconnect for AC

    I think somebody fooled around with this. That is a pretty heavy conductor feeding the box and a contactor used for motors or other large loads. My guess is that it may have been a hot tub disconnect that was modified. Why fee a heavy conductor to a contactor and then run it through a 15 amp 120-volt breaker?

    Whether electric is your strong suit or not, that is a confusing mess. It also looks like a pull-out disconnect is missing.

    Note to Jerry. I'm pretty sure they did throw in a blue wire to add to the confusion.

  4. #4
    Join Date
    May 2010
    No. San Diego Co., CA

    Default Re: exterior disconnect for AC

    ..Because the the pull-out blade is missing, looks like someone created a switch-leg for the disconnect.
    Also, I was under the impression that a GFCI should not be incorporated into the box, though could be mis-informed. Is the GFCI loose, what is it secured to and how?

  5. #5
    Join Date
    Aug 2008

    Default Re: exterior disconnect for AC

    That looks like someone re purposed a gfi spa pack with the built in convenience receptacle.

    The disconnect is only a switch in the second picture.

    All answers based on unamended National Electrical codes.


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