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Thread: Condenser seal tight

  1. #1

    Condenser seal tight

    See photos.

    There is a break in the whip feeding the condenser. There is a green wire (I am assuming it is a ground wire), but it is not bonded to the disconnect. So, if there is a fault on the disconnect, the seal tight is broken in two spots, where will the fault currect go?

    Also, why are temperature control wires mixed with line voltage in the same raceway? Although the wiring is rated for 600 volts, my understanding is that line voltage conductors and temp control conductors are different class circuts and can't be run in the same conduit.

    Agree? I'm looking for opinions. Thanks!
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  2. #2
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    Unless the A/C unit is grounded correctly the fault current may not have an adequate fault current path and the equipment would stay energized.

    The EGC needs to be connect correctly to the A/C unit disconnecting means.

    Class 2 and 3 circuit conductors are not permitted to be installed in the same raceway with power and lighting circuits.

    Now Exception #2 to 725,130(A) may come into play and would allow someone to re-classify the circuit as a class 1 and follow the rules of a class 1 circuit which would allow the conductors in the same raceway with power conductors provided that they are functionally related.

    Chris

  3. #3
    Quote Originally Posted by raider1 View Post
    Unless the A/C unit is grounded correctly the fault current may not have an adequate fault current path and the equipment would stay energized.

    The EGC needs to be connect correctly to the A/C unit disconnecting means.

    Class 2 and 3 circuit conductors are not permitted to be installed in the same raceway with power and lighting circuits.

    Now Exception #2 to 725,130(A) may come into play and would allow someone to re-classify the circuit as a class 1 and follow the rules of a class 1 circuit which would allow the conductors in the same raceway with power conductors provided that they are functionally related.

    Chris
    When you say funtionaly related are you refering to the condition that the control[what I believe to be Class 2 circuits]conductors may be run in the same raceway as the power conductors. Now these conductors pass straight through the load disconnect switch[this switch is used as a pull box for the controlls there are two wires spliced in this device]. The disconect and the condenser that it is feeding are located on the roof top. I have yet to go into the tenant space and trace the conduit back to its source. I also do not know at what point the class2[or control conductors leave the class 1 raceway. Thank You for your response

  4. #4
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    I just saw a job where an HVAC contractor stuffed ROMEX into seal tight on a roof top. and then ran the seal tight through the roof, to the junction box under the roof. One of those mr. slim a/c units. And you can't argue with the HVAC guys.

  5. #5
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    I think there is a chance the fault current will flow through the refregirent copper lines.

    As I understgand it, Art 725 prohibits the low voltage controls being mixed with the power.
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

  6. #6
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    Quote Originally Posted by raider1 View Post
    Now Exception #2 to 725,130(A) may come into play and would allow someone to re-classify the circuit as a class 1 and follow the rules of a class 1 circuit which would allow the conductors in the same raceway with power conductors provided that they are functionally related.
    That means re-classifying the entire control circuit to a class 1 circuit. The class 2 thermostat, and any class 2 cables used are the biggest problems, they will all need to be changed to class 1 products/methods.

    Quote Originally Posted by the blur View Post
    I just saw a job where an HVAC contractor stuffed ROMEX into seal tight on a roof top. and then ran the seal tight through the roof, to the junction box under the roof. One of those mr. slim a/c units. And you can't argue with the HVAC guys.
    You want to stop HVAC guys from doing these installs - let the electrical AHJ deal with them. Getting fined for working without license or permits from electrical AHJ will stop these installs faster than anything you do.

  7. #7
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    Around here, the building dept doesn't deal with electrical work. all electrical inpsections are done by privately owned UL inspection companies. The building dept handles plumbing inspections, but not drywell inspections. It's very complex to get a CO on a construction job.

  8. #8
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    Quote Originally Posted by augie47 View Post
    I think there is a chance the fault current will flow through the refregirent copper lines.

    As I understgand it, Art 725 prohibits the low voltage controls being mixed with the power.
    725 prohibits Class 2 and 3 circuits from being installed in the same raceway with power and lighting conductors, but a Class 1 circuit that is functionally associated with the equipment and run with a Chapter 3 wiring method can be in the same raceway.

    Chris

  9. #9
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    Quote Originally Posted by kwired View Post
    That means re-classifying the entire control circuit to a class 1 circuit. The class 2 thermostat, and any class 2 cables used are the biggest problems, they will all need to be changed to class 1 products/methods
    Correct, to use the exception you must remark the power supply source as a class 1 and wire the entire circuit with a Chapter 3 wiring method.

    Chris

  10. #10
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    I'm a bit confused .... maybe it's my ignorance showing ...

    What's with all the references to 725? The scope of 725 is 'circuits that are not an integral part of the appliance.' I submit that the thermostat line IS an integral part of the appliance (try operating the system without one), so 725 is irrelevant.

    From a technical standpoint, the thermostat / control wire needs to carry some current to operate a relay; the minor amount of induced voltage that would fool a PLC isn't going to operate the relay on the circuit board. Same wiring as the power circuit? You want to show me the 10-conductor romex, or the fitting on the thermostat to accept the conduit?

    This is not simply a moot point. With the increasing use of 'mini-split' systems, ther will be more instances of the thermostat/ control wire following the same path as the power wire. (In mini-splits, the indoor units often get their power direct from the outdoor unit, and these wires accompany / parallel the line sets to the indoor units).

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