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Thread: main diconnect

  1. #1
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    Default main diconnect

    what i found today was a two wires installed on each phase at the main breaker. two smaller wires lead to a 3 phase A/C breaker box. is this acceptable?

    thanks in advance,
    steve

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  2. #2
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    Default Re: main diconnect

    No. 1.Those lugs should not be double tapped.
    2. The smaller gauge wire is likely not rated for the size of the supply. It needs to be protected by a smaller breaker downstream from the main breaker.
    Do you have a pic of the panel less close up?
    By 3 Phase, do you mean 3 wire, 2 hots and a neutral?
    What size in amps is the main breaker?

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  3. #3
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    Default Re: main disconnect

    thanks for the response John, yes it is 3 phase (2 hot & 1 neutral). it appears the high leg runs from load side meter to A/C breaker panel that is located opposite of garage wall. Please see phote as you requested. also you will see 30 inch clearance ignored at the side of panel. note: 150-amp main breaker.

    steve

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  4. #4
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    Default Re: main diconnect

    Not picking up what you're putting down.

    Not a delta breaker in the first. Not buying poly-phase with high-leg, or transformer/SDS.

    Three-conductor service may be split single phase (center tapped, 120V to ground from A or B, and 240V A to B) or poly-phase supply (A or B to ground 120V, A to B 208V) residential. Doubful you have 208 V between A & B, eitherway not three-phase, and not delta or high-leg.

    Start over, providing necessary information and correct terms. Perhaps somemore basic electrical theory and education.

    To your first post question, no improper use of equipment, terminals not designed for multiple conductors, nor conductors of differing sizes. Improper tap, no hold-down bracket. Premisis service disconnects must be grouped.

    JK requested full view of original area photographed. Picture of dead-front cover in place is not helpful in addressing questions regarding what is behind same. No photoshop wiz here that can see through a photographed deadfront.

    See nothing in either cropped photo as posted to indicate a restriction or encroachment on a 30" workspace width clearance - that 30" in no way is required to be centered - nothing shown indicates there is any restriction to the right - unless we're supposed to devine the white wall surface is supposed to be perpendicular and in some way prevents the cabinet door from opening more than 90 degrees.

    Last edited by H.G. Watson, Sr.; 02-22-2011 at 07:42 AM.

  5. #5
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    Default Re: main diconnect

    Three phase has 3 hot legs and normally a neutral. This is not 3 phase with what you have described. Two hots and a neutral is typical of a 120/240 3 wire single phase system.


  6. #6
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    Default Re: main diconnect

    sorry guys what i meant to say is (3 hot wires). the a/c unit is 3 phase. thank you anyway for clearing up the question in regards to double tapping.

    steve


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    Default Re: main diconnect

    Quote Originally Posted by steve mcgown View Post
    sorry guys what i meant to say is (3 hot wires). the a/c unit is 3 phase. thank you anyway for clearing up the question in regards to double tapping.

    steve
    A neutral is not a "hot" conductor, although it may carry unbalanced current.

    I seriously doubt your representation that present would be a three-phase airconditioning unit.


  8. #8
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    Default Re: main diconnect

    this is the breaker box located on oppisite side (has three fuses inside). which tells me a/c is 3 phase! also data plate on unit indicates 3 phase.

    steve


  9. #9
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    Default Re: main diconnect

    this is the breaker box located on oppisite side (has three fuses inside). which tells me a/c is 3 phase! also data plate on unit indicates 3 phase.

    steve

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  10. #10
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    Default Re: main diconnect

    Quote Originally Posted by steve mcgown View Post
    this is the breaker box located on oppisite side (has three fuses inside). which tells me a/c is 3 phase! also data plate on unit indicates 3 phase.

    steve
    Steve,
    First off I am not jurking your chain or casting any dispersions on your interpenetration of what you saw. Some here jump down the throats of those who post questions.

    Three phase is something seldom used in non-commercial applications. I have worked to understand the three phase applications and am still expanding my understandings.

    In a three phase system there is a different transformer that is used which has an extra coil and converter that creates that third phase which is sent to the meter and service panel. Most residential installations have single phase electric. Which has two lines that are of different phases and is refereed to as single phase. There is not a common term as two phase, which has always perplexed me to understand why. If you were to look at the mast head did you see four wires or just three. If there as a three phase supply to the property then there should be four wires coming to the mast head. What was coming into the property?

    It is not uncommon to have equipment that can be used as either 120 or 240. Though it does require a wiring change in that equipment to to so. A 240 motor will not run on the same leg (same phase). It requires two different legs (two different phases) to run. Which is why I have never really understood why it is not referred to as two phase. With what I have seen, equipment that is designed for three phase is not addaptable to single phase. I may be wrong, just haven't seen it. Is it possible that the AC had been converted?

    Was the AC a commercial unit?
    Also, did the breaker box with thee fuses have three different lugs and three separate bars for the fuses?
    What type of fuses were in this box?


  11. #11
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    Default Re: main diconnect

    What Garry says, the A/C unit may well be 3 phase supplied directly from the service equipment outside.
    The distribution panel inside appears to be normal residential single phase. The double taps may supply some other part of the house with single phase.
    This part of the installation needs repair by a qualified electrician. The panel appears to be full, so this will be an expensive repair.

    We would now like a picture of the weather head to see if there is 3 phase coming in from the street. Maybe try picking it up with Google Streetview?

    Last edited by John Kogel; 02-22-2011 at 12:44 PM.
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    Default Re: main diconnect

    There may also be an issue if the services are not grouped as required.


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    Default Re: main diconnect

    Quote Originally Posted by Jim Port View Post
    There may also be an issue if the services are not grouped as required.
    Yep, as mentioned smack dab in the middle of my post #4. Thanks for "also" agreeing.


  14. #14
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    Default Re: main diconnect

    ok gentlemen, i believe we got off into a different topic of discussion (instead of the double tap that was observed). Which i am very grateful for all who replied. Furthermore or FYI here in Houston long time ago in the 60's 3 phase 4 wire was used in various residential homes. You will still find 3 phase 4 wire meters installed (such as subject house). This particular house had open wire secondary with 4 wires (drops) attached to weather head. I apologize if my previous interpretations appeared incompetent.

    Steve

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  15. #15
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    Default Re: main disconnect

    Quote Originally Posted by steve mcgown View Post
    what i found today was a two wires installed on each phase at the main breaker. two smaller wires lead to a 3 phase A/C breaker box. is this acceptable?
    To cut to the chase of it all ...
    what i found today was a two wires installed on each phase at the main breaker.

    is this acceptable?
    No ... unless ...

    No, multiple tapped terminals are not allowed unless the terminal is identified for more than one conductor, and I doubt those terminals are so rated.

    Additionally #1: Those multiple tapped conductors going to the a/c disconnect probably do not meet the tap rules anyway (which do not matter as the multiple tap is the first problem in a chain of problems).

    Additionally #2: Those grounds which are twisted together should be untwisted and go to their own terminals, or, at most, two to a terminal (provided the terminals are rated for more than one grounding conductor - older equipment was not rated that way, most newer equipment is rated for that).

    Additionally #3: Looks like the smaller conductors multiple tapped to the a/c disconnect are bent too sharply - at least it looks that way.

    Jerry Peck, Construction / Litigation Consultant
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  16. #16
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    Default Re: main diconnect

    Steve,
    As you soon will understand the members that respond to posts will inevitably find more than what was in the original post statement or question. Some times the divergence is right away, other times it takes a little longer. Furthermore, It is not uncommon that the entire thread is completely diverted to a diferent topics.

    I find that this site gives me an insight to the varied laws, applications of building code, method and designs in various states. Saves me a lot of traveling, seeing the world through other member eyes.

    Residential with 3 phase, would like to know the rationality that went into that decision.
    Maybe the utility company misordered their transformers and instead of 100 the received 10,000, a fuzzy number on purchase order.

    Anyway, it is interesting that it was not uncommon for the 3 phase install during that time frame and location. Learn something new every day.... thanks


  17. #17
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    Default Re: main diconnect

    From our old friends at FPE.... not sure I fully understand the benefit, but here it is.

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  18. #18
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    Default Re: main disconnect

    Quote Originally Posted by Garry Sorrells View Post
    Residential with 3 phase, would like to know the rationality that went into that decision.
    Maybe the utility company misordered their transformers and instead of 100 the received 10,000, a fuzzy number on purchase order.

    Quite common in the older and richer areas of Miami back in the 1950s and 1960s, some in Fort Lauderdale and Boca Raton areas too.

    Basically all 3-phase was ever used for was the a/c units.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  19. #19
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    Default Re: main disconnect

    Quote Originally Posted by Jerry Peck View Post
    Quite common in the older and richer areas of Miami back in the 1950s and 1960s, some in Fort Lauderdale and Boca Raton areas too.

    Basically all 3-phase was ever used for was the a/c units.
    Phoenix also has resi 3 also for the same reason...


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