Air conditioner compressor

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I agree with david . not sure what a fused disconnect has to do with anything. I dont use them anyway always use the cheapie 60 amp unfused pullouts which are very adequate for hvac apps. The only tiome I use a fused disconnect is if the unit calls for fuses instead of bereakers or if I am connectiong to a zinsco or fpr breaker which are not rated for hvac apps. Then you fuse it at the disconnect to avoid the hassle.
 
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stew said:
I agree with david . not sure what a fused disconnect has to do with anything. I dont use them anyway always use the cheapie 60 amp unfused pullouts which are very adequate for hvac apps.
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In that case you would be allowed to run the #10 to a 40amp breaker.
 
iwire said:
Only from the fused disco to the unit, not from the panel to the fused disconnect.
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From the fused disconnect to the unit is a branch circuit. The #10 from the panel to the fused disconnect is a feeder, and would be compliant with 430.62. #10 would be acceptable for both feeder conductors and branch circuit conductors. So adding a fused disconnect is irrelevant.
 
david luchini said:
From the fused disconnect to the unit is a branch circuit. The #10 from the panel to the fused disconnect is a feeder, and would be compliant with 430.62. #10 would be acceptable for both feeder conductors and branch circuit conductors. So adding a fused disconnect is irrelevant.
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I know the difference between a branch circuit and feeder.:roll:

IMO 430.62 does not apply to this installation.
 
david luchini said:
How could it not? You would have a feeder supplying motor loads including a hermetic refrigerant motor compressor. If 430.62 doesn't apply to this feeder, then what section does?
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Take a look at 440.6, it tells us exactly how the size of the condutors are to be determined and Article 430 is not part of it.

440.6 Ampacity and Rating. The size of conductors for
equipment covered by this article shall be selected from
Table 310.16 through Table 310.19 or calculated in
accordance with 310.15 as applicable. The required ampacity of
conductors and rating of equipment shall be determined
according to 440.6(A) and 440.6(B).

(A) Hermetic Refrigerant Motor-Compressor. For a hermetic
refrigerant motor-compressor, the rated-load current
marked on the nameplate of the equipment in which the
motor-compressor is employed shall be used in determining
the rating or ampacity of the disconnecting means, the
branch-circuit conductors, the controller, the branch-circuit
short-circuit and ground-fault protection, and the separate
motor overload protection. Where no rated-load current is
shown on the equipment nameplate, the rated-load current
shown on the compressor nameplate shall be used.

Exception No. 1: Where so marked, the branch-circuit selection
current shall be used instead of the rated-load current
to determine the rating or ampacity of the disconnecting
means, the branch-circuit conductors, the controller,
and the branch-circuit short-circuit and ground-fault
protection.

Exception No. 2: For cord-and-plug-connected equipment,
the nameplate marking shall be used in accordance with
440.22(B), Exception No. 2.

(B) Multimotor Equipment. For multimotor equipment
employing a shaded-pole or permanent split-capacitor-type
fan or blower motor, the full-load current for such motor
marked on the nameplate of the equipment in which the fan
or blower motor is employed shall be used instead of the
horsepower rating to determine the ampacity or rating of
the disconnecting means, the branch-circuit conductors, the
controller, the branch-circuit short-circuit and ground-fault
protection, and the separate overload protection. This marking
on the equipment nameplate shall not be less than the
current marked on the fan or blower motor nameplate
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No mention of Article 430 or the feeder conductors.
 
exactly correct david and those who are splitting hairs are in my opinion doing just that. I think the code makers need to add the 430 verbage into the 440 verbage to get this straight.Branch circuit or feeder call it what you will but the fact is it is the wire feeding a motor load and can be installed with the 40 amp fused disconnect . I for one have installed hundreds and more hvac units and never had a problem unless I run in to an inspector who doesnt understand the electric motor concept.
 
stew said:
exactly correct david and those who are splitting hairs are in my opinion doing just that. I think the code makers need to add the 430 verbage into the 440 verbage to get this straight.Branch circuit or feeder call it what you will but the fact is it is the wire feeding a motor load and can be installed with the 40 amp fused disconnect . I for one have installed hundreds and more hvac units and never had a problem unless I run in to an inspector who doesnt understand the electric motor concept.
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Stew, when talking about the NEC you have to forget what commonsense tells you and just read the words as written in the NEC.:)
 
iwire said:
Take a look at 440.6, it tells us exactly how the size of the condutors are to be determined and Article 430 is not part of it.
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I think you are missing something. 440.6 says "The size of conductors for equipment covered by this article..."

440.1 says "The provisions of this article apply to electric motor-driven air-conditioning and refrigeration equipment and to the branch circuits and controllers for such equipment..."

Article 440 (and 440.6) tells you how to size the branch circuit conductors only, not feeder conductors. For feeder conductors feeding the A/C equipment, you will have to look elsewhere.


iwire said:
No mention of Article 430 or the feeder conductors.
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440.3 says "These provisions are in addition to, or amendatory of, the provisions of Article 430..." This is a very clear mention of Article 430.

And to complete the circle, 430.62 (for feeder SCGF protection) references 440.22(A) for feeders to the motor-compressor equipment in Art. 440. The feeder to the equipment in Art. 440 should be sized from Art. 430 (as 440 references 430 and vice-versa.)

If you disagree, I would ask again, what section would you use to size a feeder and feeder protection to the equipment in Art. 440.
 
stew said:
exactly correct david and those who are splitting hairs are in my opinion doing just that. I think the code makers need to add the 430 verbage into the 440 verbage to get this straight.
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I think the verbiage is already there (ie, 440.3 references Art. 430, and 430.62 references Art. 440.) I feel it is just be overlooked.
 
iwire said:
Only from the fused disco to the unit, not from the panel to the fused disconnect.
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Read the question or statement I responded to. He said he used an "unfused" disconnect. The branch circuit is from the "final overcurrent device". In his example he would just have a service disconnect switch.

I also agree that the feeders are not mentioned anywhere in 440.6(A).

Feeders are apples and branch circuits are oranges.
 
I prefer common sense . And I still agree with david I beleive he is spot on correct. If the wire from the panel was going to another panel with multiple loads and not just a single load then I would agree you would need larger wire but when it feeds just the hvac load then the mca can be used for this IMHO.(my common sense tells me so.lol)
 
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David,
Until I read your post I would have said that the wire would have had to be full size between the breaker and the OCPD at the unit. I had not looked at the scope of Article 440. You are correct that feeders are outside the scope of that article.
 
don_resqcapt19 said:
David,
Until I read your post I would have said that the wire would have had to be full size between the breaker and the OCPD at the unit. I had not looked at the scope of Article 440. You are correct that feeders are outside the scope of that article.
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I also agree that feeders are outside the scope of 440. Feeders supplying motor loads can have overcurrent protecition higher than the ampacity of feeder conductors to allowing starting of the motor(s).

David Luchini has already directed us to 430.62. That section does tell us that the OP situation is acceptable even if he had a fuse or breaker at the AC unit.
 
spooky42,
I think the advice in post #2 might be the best you can do. Discuss that with the inspector and perhaps you can show him why it is legal.
I have found that referencing motors and starting current sometime helps. For some reason some folks don't equate compressors and motors.
 
You can't jump Articles to suit your whims. We are not in 430, we are in 440.

That would be like trying to say it's not a mobile home, it's a single family dwelling unit. Doesn't work that way.
 
Consider this.

440.3(B) Articles 422, 424, or 430. The rules of Articles 422, 424, or 430, as applicable, shall apply to air-conditioning and refrigerating equipment that does not incorporate a hermetic refrigerant motor-compressor. This equipment includes devices that employ refrigeration compressors driven by conventional motors, furnaces with air-conditioning conditioning evaporator coils installed, fan-coil units, remote forced air-cooled condensers, remote commercial refrigerators, and so forth.
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IMO this puts 430 off limits for most outdoor condenser compressor unit conductors.
 
cowboyjwc said:
You can't jump Articles to suit your whims. We are not in 430, we are in 440.

That would be like trying to say it's not a mobile home, it's a single family dwelling unit. Doesn't work that way.
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We are not jumping Articles. Art 440 says that the provisions of Article 430 also apply to A/C&R equipment, except as amended in 440. The only amendments in 440 are regarding the branch circuits to the A/C&R equipment. The feeder provisions of 430 still apply to A/C&R equipment because Article 440 says they do.
 
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