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  1. #1
    Join Date
    Feb 2006
    Location
    South Texas
    Posts
    1
    New home, with an Amana unit in the upstairs. The AC installer came to me and said he would like to see separate runs of electrical to the unit, 60amp and 30amp breakers for the 15KW heat strip. AC installer says normal runs are 6 gauge to the 60 and a 10 gauge to the 30, from the main breaker panel.
    The electrician has run a 4 gauge to a terminal box(lack of true name for the box)3ft from the unit. From here, he has a 6gauge to the 60 and a 10guage to the 30.
    Since I am not a professional AC or electrical installer, I have to turn to you guys for your opinion.
    Note: The AC company is a rather large company, serving several counties and has been here since 78. The installer has been with the company for 8years.
    Electrical company is also a large company. The workers did not speak english very well,(not uncommon for Texas) so I wanted to get you guys professional opinion before I protest or not....

  2. #2
    Join Date
    Jul 2004
    Location
    midwest
    Posts
    2,868
    The #4 wire is alright depending on how many feet of wire there is.
    There has to be breakers in the box before the air handler for the #6 and #10. If there are no breakers in the box where the wires split it needs changed.

    When a single wire is used its normally done by running the single feed all the way to the air handler.

  3. #3
    Join Date
    Oct 2004
    Posts
    3,400
    The proper name for the other box is a "sub-panel", if it has circuit breakers in it.

    If he is using a sub-panel, I would be okay with that, as long as he follows National Electrical Code. Some of the variables are distance, and type of insulation on the wire.

    However,

    If Sparky is simply connecting all of the wires together inside of a box, then it becomes a "junction box".

    I would lobby for separate pulls, or a sub-panel.

  4. #4
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    It gets done both ways. Either way is fine. We all have our preferences.
    There is nothing more frightful than ignorance in action....Mark Twain

  5. #5
    Join Date
    Nov 2000
    Location
    Coastal Georgia
    Posts
    34,902
    I take it this has been installed already. Did they slip some aluminum wire in?

    You can tell electricians you don't want AL and they will make sure they do it anyway

  6. #6
    Join Date
    Dec 2003
    Location
    Location!, Location!
    Posts
    929
    #4 copper THHN is rated @ 90 amps in a raceway, so with total circuit protection @90(60+30), before the voltage drop/length of run calcs, you seem to be protected. Is the run in 3/4" thinwall? The unit has 60 and 30 amp breakers in it for connection? If not, you need to protect the #10 and #6 seperately-they cannot be protected by the main brkr to the #4(what size is that breaker?) Don't forget to confirm adequate ground for all circuits.

  7. #7
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    The whole key is that terminal(junction) box....does it have breakers/fuses in it?Does it have a lever on the side of it(a disconnect?)
    If everything was always done "by the book"....the book would never change.

  8. #8
    Join Date
    Feb 2003
    Posts
    1,996
    The sub-panel should have a 100amp breaker. You should never pull the full 90 amps of power unles something was wrong with the unit.

  9. #9
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    what is the amp draw of the unit? FLA?
    what is the LRA?
    what wire size does the unit name plate call for?

    90C rating of #4 wire is tops, the use of 60C saves $ whenever the load is operating!

    what wire type are they using?
    how many wires in conduit?
    in cable or conduit?
    how long is the run from service panel to box?
    is any of the wire in the attic?
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  10. #10
    Join Date
    Sep 2004
    Location
    Memphis
    Posts
    2,502
    IMO its a new house, so the hvac guy is responsible for installing the system & the electrician is responsible for powering it. I dont see where the hvac guy has a right to tell the electrician how to power the units. If I was the electrician, I'd be tellin the hvac installer to just concentrate on his own stuff & quit meddlin in mine.
    Life is like a jar of jalapenos. What you do today might burn your ass tomorrow.

  11. #11
    Join Date
    May 2001
    Location
    Kansas City
    Posts
    2,729
    Originally posted by rimek
    #4 copper THHN is rated @ 90 amps in a raceway, so with total circuit protection @90(60+30), before the voltage drop/length of run calcs, you seem to be protected.
    This is wrong, the 90*c column you looked that up in is to be used for deration corrections only. You can't go over the termination rating, which would be 75*c. But under 100 amps you have to use the 60*c column which is 70amps for #4 copper. That #4 from the main panel can only be protected by a 70amp breaker, and that's before you allow for voltage drop.

  12. #12
    Join Date
    May 2001
    Location
    Kansas City
    Posts
    2,729
    Originally posted by cem-bsee
    what is the amp draw of the unit? FLA?
    what is the LRA?
    what wire size does the unit name plate call for?

    90C rating of #4 wire is tops, the use of 60C saves $ whenever the load is operating!

    what wire type are they using?
    how many wires in conduit?
    in cable or conduit?
    how long is the run from service panel to box?
    is any of the wire in the attic?
    I thought about if the wire was in the attic but it will never be over 86* in the winter, since we have to use the 60c rating of 70amps for #4 it doesn't matter what type of wire insulation it is either.
    Yes need to look at the amp draw of the unit, 15kw at 240v is 62.5amps the blower & controls shouldn't be over 5amps so a 70amp breaker would probably hold.
    The 'termination box' needs to be a subpanel with a 30 & 60 amp breakers.

  13. #13
    Join Date
    Nov 2000
    Location
    Waco, Texas, USA
    Posts
    6,153
    Westend I hope you are somewhat confused.

    I think your a/c guy meant he wants a "dedicated circuit" to serve the outdoor unit. He didn't like seeing the outdoor unit served by double lugging the wire with the AHU.

    This set up works ok with electric heat although it is a code violation....unless double lugging is ok?

    But what does the a/c guy do if they want to upgrade to a heat pump one day? Now the circuit isn't big enough....big problem in our area of Central Texas.
    "And remember my sentimental friend......that a heart is not judged by how much you love, but by how much you are loved by others" - Wizard of Oz.

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