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Thread: Condenser seal tight

  1. #21
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    You have well summed up exactly where we disagree.

    Either you have a problem with the wires next to each other, or you do not. Whether whte THHN wires are loose, inside a pipe, with the thermostat wires, or wrapped in a jacket and called "Romex" won't matter - at least not in a technical sense.

    Look to your specs for running CAT-5 data circuits. That confirms thi point. There's a situation where there's a problem with 'low voltage' being close to 'power.'

    As for the thermostat and it's associated air conditioner, I think the code, and Webster's are pretty clear: There's no such prohibition, and the cited section does not apply.

    Unless, of course, one wishes to maintain that the code is absolute, arbitrary, and it's words defined only by the convenience of the moment.

  2. #22
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    Quote Originally Posted by renosteinke View Post
    You have well summed up exactly where we disagree.

    Either you have a problem with the wires next to each other, or you do not. Whether whte THHN wires are loose, inside a pipe, with the thermostat wires, or wrapped in a jacket and called "Romex" won't matter - at least not in a technical sense.

    Look to your specs for running CAT-5 data circuits. That confirms thi point. There's a situation where there's a problem with 'low voltage' being close to 'power.'

    As for the thermostat and it's associated air conditioner, I think the code, and Webster's are pretty clear: There's no such prohibition, and the cited section does not apply.

    Unless, of course, one wishes to maintain that the code is absolute, arbitrary, and it's words defined only by the convenience of the moment.
    Wrapped in a jacket called "Romex" does matter. NM cable is a wiring method by itself. THHN/THWN is not and must be inside a raceway. You can place the class 2 control cable right next to a raceway, you can place the class 2 control cable right next to a NM cable. You can not place the class 2 control cable in the raceway with class 1 or power conductors.

  3. #23
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    Right. We are in agreement that Romex is a wiring method, and that you can place a thermostat wire right next to it.

    What you appear to either not understand, or choose to ignore, is my assertion that the code rules, as you present them, are illogical. It is my contention that either your understanding of the rules is wrong, or the code itself is wrong. Bad code makes for bad law.

    You dishonestly throw in a reference to Class 2 control cables. Your reference is dishonest because the code section cited clearly says 'do not apply this section in this situation.' We are talking about the thermostat line for the air conditioner it controls, and code is quite clear: the cable and the power CAN be run together. That's the import of the use of the word 'integral' in the cited code section.

    Unless, of course, we're not speaking English anymore.

  4. #24
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    Quote Originally Posted by renosteinke View Post
    Right. We are in agreement that Romex is a wiring method, and that you can place a thermostat wire right next to it.
    Agreed

    What you appear to either not understand, or choose to ignore, is my assertion that the code rules, as you present them, are illogical. It is my contention that either your understanding of the rules is wrong, or the code itself is wrong. Bad code makes for bad law.
    There is nothing illogical about the codes under discussion.


    You dishonestly throw in a reference to Class 2 control cables. Your reference is dishonest because the code section cited clearly says 'do not apply this section in this situation.'
    Please tell me the code section that says 'do not apply this section in this situation'?


    We are talking about the thermostat line for the air conditioner it controls, and code is quite clear: the cable and the power CAN be run together.
    Please tell me the code section that says the thermostat cable and THHN power conductors can be run in the same conduit.


    That's the import of the use of the word 'integral' in the cited code section.


    There is absolutely no field wiring installed for an AC unit that is 'integral' to the AC unit.

    The thermostat conductor we install between the unit and the thermostat are directly covered by Article 725

    Unless, of course, we're not speaking English anymore.
    How is that helpful?

  5. #25
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    Well, I guess we're talking different forms of the English language.

    My NEC says, under the scope of the cited section, that the section does not apply to control wires integral to the equipment.

    Websters - which is used by my version of the English language - defines integral everything necessary to make the air conditioner work.

    Therefore, the thermostat cable is an integral part of the air conditioner, thus the cited section does not apply. Seems pretty plain to me.

    I notice a common practice, in many posts in this thread, to use general terms such as 'thermostat cable' or 'control wire,' as if all were the same. This is not the case. The cited section is perfectly plain that it applies only to control wires that are not required for the operation of that specific appliance.

    Thus, the same wire, off the same bulk roll of material, would be in violation were it used for another purpose; say, as a doorbell wire sharing conduit with the air conditioner power circuit.

    Less obvious is that not every 'low voltage' circuit is a 'power limited' circuit. Indeed, I suspect that most thermostat circuits are not 'power limited.' That term has a specific meaning to UL, with specific testing protocols, where the desire is to absolutely guarantee that the circuit never get more than a certain amount of power. An example of such an application would be for an 'intrinsically safe' application. Even the use of a "Class 2" transformer is not, in itself, enough to make it a 'power limited' circuit; the transformer is but a part.

    IMO, Article 725 is grossly mis-applied, and this remains the case despite the code making it quite plain with the qualification in their scope of the article. That this article is numbered in the 700's ... as one of the exceptional, very limited circumstances .... and not in the 300's as a general rule for wiring methods ought to be another clue. One might as well try to apply 760 (Fire Alram Systems) to thermostat circuits- so what if it's outside the scope of the article!

    To sum it up ...
    1) The code does not prohibit the practice; and,
    2) There is not technical reason to require the separation.

    Thus, the question is: How can it be logical to assert there's anything wrong with the practice?

  6. #26
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    Integral can also be read as "internal parts of the equipment" and that is its intended meaning in Article 725. If we would use your definition, then there would be no application for Article 725.
    There is no question that Article 725 applies to the control circuit for a HVAC system. As far as the transformer not making a circuit a Class 2 circuit, that is exactly what does make it a Class 2 circuit. Look at 725.121(A). A listed Class 2 transformer or power supply is all you need to be able to say that the circuit is a Class 2 circuit.
    Don, Illinois
    "It is the first responsibility of every citizen to question authority." B Franklin

  7. #27
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    Quote Originally Posted by renosteinke View Post
    To sum it up ...
    1) The code does not prohibit the practice; and,
    2) There is not technical reason to require the separation.
    To sum it up.

    1) You are wrong. 725.136 prohibits it.

    2) The reason is a fault in a conduit containing both power and class 2 condutors can cause a higher voltage and current onto the class 2 wiring.


    725.136 Separation from Electric Light, Power, Class 1,
    Non–Power-Limited Fire Alarm Circuit Conductors,
    and Medium-Power Network-Powered Broadband
    Communications Cables.

    (A) General. Cables and conductors of Class 2 and Class 3
    circuits shall not be placed in any cable, cable tray, compartment,
    enclosure, manhole, outlet box, device box, raceway,
    or similar fitting with conductors of electric light,
    power,
    Class 1, non–power-limited fire alarm circuits, and
    medium-power network-powered broadband communications
    circuits unless permitted by 725.136(B) through (I).

  8. #28
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    Quote Originally Posted by renosteinke View Post
    My NEC says, under the scope of the cited section, that the section does not apply to control wires integral to the equipment.
    Can you tell me what section you are looking at?

    Websters - which is used by my version of the English language - defines integral everything necessary to make the air conditioner work.

    Therefore, the thermostat cable is an integral part of the air conditioner, thus the cited section does not apply. Seems pretty plain to me.
    So simple it is incorrect.


    By your choice of defintion the branch circuit is also integral to the unit.

    As would be the panel, the service and all the wiring back to the power company genertor. The unit cannot run without the branch circuit even more than it cannot run with out a thermatst.

    I notice a common practice, in many posts in this thread, to use general terms such as 'thermostat cable' or 'control wire,' as if all were the same. This is not the case. The cited section is perfectly plain that it applies only to control wires that are not required for the operation of that specific appliance.
    Again, the thermostat wiring is in fact covered by 725.

    Less obvious is that not every 'low voltage' circuit is a 'power limited' circuit. Indeed, I suspect that most thermostat circuits are not 'power limited.' That term has a specific meaning to UL, with specific testing protocols, where the desire is to absolutely guarantee that the circuit never get more than a certain amount of power. An example of such an application would be for an 'intrinsically safe' application. Even the use of a "Class 2" transformer is not, in itself, enough to make it a 'power limited' circuit; the transformer is but a part.
    Actully as long as the transfomer is marked class 2 all the wiring on the load side of it is class 2.

    IMO, Article 725 is grossly mis-applied,
    And IMO you have grossly misinterpreted it.
    Last edited by iwire; 04-16-12 at 09:10 PM.

  9. #29
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    IMHO there is absolutely no doubt that class 2 circuits cannot be run in the same raceway as power conductors. I think the code is crystal clear on this and I have never seen an AHJ, instructor, peer, etc say otherwise. Some say you can "reclassify" the circuit as a class 1, which I also think is bogus. If the entire circuit including the supply and all the components are designed and built to class 2 standards, there is no such thing as reclassifying it.
    Back in the '70's in some areas it was common practice however to mix power and class 2 wiring, but I don't think even back then it was code compliant. Also in some areas it was thought if you used rated conductors it was OK, but I don't think this was ever compliant either.

  10. #30
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    Quote Originally Posted by texie View Post
    Some say you can "reclassify" the circuit as a class 1, which I also think is bogus. If the entire circuit including the supply and all the components are designed and built to class 2 standards, there is no such thing as reclassifying it.
    I mentioned this early in this thread. To reclassify it, you have to get rid of CL2 cables and use use a Ch 3 wiring method, you would need to replace the thermostat or any other device with devices that do not have class 2 ratings. If you wanted to pull control conductors in raceway with power conductors they would need insulation rating equal or greater than voltage of power circuit.

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