A/C disconnect

[eddieK]

You haven't given us any proof that there have been problems caused by the wire being sized at minimum either... Show me pictures of damage, wire temp readings, anything at all and we might listen...



What you are preaching is AN acceptable practice, there are others.
What the manufacturer recommends is clearly spelled out on the nameplate. It does not back up your logic. Safest would be to not install the A/C at all, no worries then. Better yet don't install any electric or gas in your house.

I am concerned with installing the most practical circuit I can. Many times I have installed #10 on for a unit that only pulls 15A but calls for a 30A breaker, often times because nobody knows the specs for the unit until it's sitting there. I have also ran 10's for a unit that called for a 50A breaker. What I won't do is support your BS logic.

I told you I have seen the results...

I am doing exactly what the nameplate requires. Exactly.

Over sizing wire is fine, under sizing is NEVER okay.

Never EVER install #10 with 50 amp breaker, EVER. You are not protecting the wire.

 

[eddieK]

Wow, this thread has gone beyond assured......



What do manufacturers demand?

Apparently youve never read a nameplate on an A/C. Manufacturers call for what is code permissible.

Many units call for #10 on 50a breaker. If you want to run bigger wire, nothing stopping you except maybe customer budget.

Do you upsize the ground/EGC when you upsize the ungrounded conductors?



Manufacturer recommended?

Please show me a letter from a manufacturer recommending anything but what is on the nameplate....

And what youre saying here is that the code permits unsafe wiring methods?



If you think #6 is the smallest wire that is rated for 50a, its very obvious you dont even know your ampacities. Time for you to learn the basics. #8 THWN is rated for 50a as well....

Heck, you dont even need a pysical copy of the code book. Go to NFPAs site and register for a free account. Then open a copy of NFPA 70 and go to Table 310.15(B)(16)....

And the manufacturers have already sized the wire for you. Ever read the MCA and MOCP values on a nameplate? Apparently not...

Nothing that I have recommended is unsafe, in fact it is above code.

I don't think you understand what I've been saying...

Using the NFPAs recommendations - #10 wire cannot be protected by a 50 amp breaker EVER.

Wire sizing also depends on the length, #6 is protected by a 50 amp breaker. #8 is protected by a 40 amp breaker...until length creates excessive resistance and then you upsize.

This entire discussion began because someone said early on that a #10 can be protected by a 50 amp breaker. not true

It's not called a name plate, it's called nomenclature, this is where the manufacturer lists the minimum and the maximum amp protection for wire sizing and fuse/breaker sizing. It's where you find model and serial numbers, it's where you find type of ref charge and the amount from factory, usually in ounces.

Max HVAC breaker protection means the largest circuit you can run to protect this unit from sustaining maximum amps is____ minimum ampacity means the smallest circuit you can provide this unit to avoid over taxing circuit.

It does not mean small wire and large breaker.

 

[alfredeneuman]

You said earlier "I have yet to recall finding something like was described - #10 wired to a 50 amp breaker." yet you claim "I told you I have seen the results.."

At this point I think it's better that we just agree to disagree, and don't let this BS thread continue.

 

[AntonLargiader]

Using the NFPAs recommendations - #10 wire cannot be protected by a 50 amp breaker EVER.

I'm not sure if "recommendations" differs from "requirements" in this argument, but if you're talking about what the code says then you have to take the EVER out of there.

240.4D lists the standard overcurrent requirements and the exceptions. AC equipment is the first of many exceptions listed and the modified requirements for AC are in 440. They also define Rated Load Current and which ratings are shown on the nameplate (their term, not mine).

Are you talking about something else when you say "recommendations?"

 

[tapered-pin]

seems to me people are picking only certain parts of the NEC out and showing them as "acceptable" without looking at the system as a whole (which is mandatory for any system 600v or less).

The small conductor rule would apply here and therefore there would have to be additional overcurrent protection in place (aside from the breaker).

 

[mm08822]

seems to me people are picking only certain parts of the NEC out and showing them as "acceptable" without looking at the system as a whole (which is mandatory for any system 600v or less).

The small conductor rule would apply here and therefore there would have to be additional overcurrent protection in place (aside from the breaker).

Chapters 1-4 apply to generally all installations unless modified or supplemented by later chapters.
Chapt 4 includes an entire section (Art 440) dedicated to a/c and refer equipment aside from the many other types of equipment covered. Many replies have been posted referring to complying with or exceeding art 440.
Where is “the system as a whole” been neglected? Which posts contain topics taken out of context or neglect other code requirements?

What small conductor rule are you referring to for this situation? The branch circuit ocp requirements are specified by the mfr and was part of the submitted data when the unit was tested at the ETL for compliance to gain listing. Any additional protection required is integral to the unit.

 

[alfredeneuman]

Never EVER install #10 with 50 amp breaker, EVER. You are not protecting the wire.

Try the Square D motor calculator: Insert 5 hp single phase @ 230V and see what they suggest:
www.msipump.com/images/NEMAMotorDataCalculator.xls

Hint: (#10 wire w/ a 60Amp breaker, or 40Amp dual element fuses)
......but I guess you know better

 

[eddieK]

You said earlier "I have yet to recall finding something like was described - #10 wired to a 50 amp breaker." yet you claim "I told you I have seen the results.."

At this point I think it's better that we just agree to disagree, and don't let this BS thread continue.

This has become ridiculous...It's like a fight with a teenager.

I have never seen anyone wire an A/C unit with #10 for a 50 amp circuit...where the nomenclature requires a 30 amp circuit.

I have seen properly wired systems fry panels, fry breakers, contactors etc...

Because of compressor shorts and/or overload protection failure. Usually caused by blocked coils, fan problems etc...

The reason I brought up the results is...these circuits wired correctly, as in appropriately sized wires, kept the wires in the structure from damage when the compressor went to ground and/or kept operating (short cycling) on overload protection. The results were that proper wire size and appropriate breaker protected the wire. That is the main purpose of the breaker, to protect the wire.

 

[eddieK]

I'm not sure if "recommendations" differs from "requirements" in this argument, but if you're talking about what the code says then you have to take the EVER out of there.

240.4D lists the standard overcurrent requirements and the exceptions. AC equipment is the first of many exceptions listed and the modified requirements for AC are in 440. They also define Rated Load Current and which ratings are shown on the nameplate (their term, not mine).

Are you talking about something else when you say "recommendations?"

I'm talking about standard safe circuitry practice in the trade.

 

[eddieK]

Try the Square D motor calculator: Insert 5 hp single phase @ 230V and see what they suggest:
www.msipump.com/images/NEMAMotorDataCalculator.xls

Hint: (#10 wire w/ a 60Amp breaker, or 40Amp dual element fuses)
......but I guess you know better

Motor.

We are talking compressors in A/C units. High pressure, high temp situations with blocked coils creating excessive pressures and temps.

If you ever find any electrician or HVAC tech installing a circuit that has a nomenclature reading minimum ampacity 27.8 or 35.9 and maximum circuit protection 50...with #10 wire protected by a 50 amp breaker, you have found someone installing something dangerous.

You do see often, a 50 amp breaker with appropriate wiring wired to a 30 amp disconnect with appropriate fuses in disconnect. This is common...#10 wire protected by a 50 amp breaker, nope, no way, NEVER.

 

[alfredeneuman]

Yep, I guess you think know better than Square D.
I just was pointing out that #10 could be used with a breaker larger than 30 amps (60 in this case).

I must be a 65 year old teenager

 

[wyliesdiesels]

Motor.

We are talking compressors in A/C units. High pressure, high temp situations with blocked coils creating excessive pressures and temps.

If you ever find any electrician or HVAC tech installing a circuit that has a nomenclature reading minimum ampacity 27.8 or 35.9 and maximum circuit protection 50...with #10 wire protected by a 50 amp breaker, you have found someone installing something dangerous.

You do see often, a 50 amp breaker with appropriate wiring wired to a 30 amp disconnect with appropriate fuses in disconnect. This is common...#10 wire protected by a 50 amp breaker, nope, no way, NEVER.

So why dont you come out with it.

Say it.

Repeat after me:

"What the NEC says to do in 240.4G and 440 is actually NOT safe."

Do you own a code book?

 

[AntonLargiader]

Eddie, your argument is just inconsistent. You said "Using the NFPAs recommendations - #10 wire cannot be protected by a 50 amp breaker EVER" and now it sounds like you agree it's OK for motors because some authority said it was. Well, some authority also said it was OK for AC compressors. It's not even clear what your opinion actually is, despite all you've written.

No dog in this... just saying how you're coming across. If you want to be clear, be more specific about what's OK and what's not, where, and why. "NFPA recommendations" isn't specific. Can you cite a source?

 

[brewchief]

This has become ridiculous...It's like a fight with a teenager.

I have never seen anyone wire an A/C unit with #10 for a 50 amp circuit...where the nomenclature requires a 30 amp circuit.
.

Your right Eddie this has become ridiculous, you have multiple master electricians telling you exactly where in the code to look and see for yourself how it is 100% to code to use a breaker rated higher then the wires normal ampacity rating. It is very clearly written in the NEC, remember the NEC is all about safety so if it wasn't safe it wouldn't be allowed.

As for nobody wiring equipment in this manner I beg to differ, I see it pretty frequently, this week I was in a neighborhood that every single house has a 4 ton unit wired with #10 nm-b on a 40 or 50 amp breaker, many of these units have seen little to no maintenance but we don't see wires burning up from it.

This is an area of the code that is often misunderstood, feel free to go talk to your local electrical inspector and get his/her opinion.

 

[Bert_]

I told you I have seen the results...

So then give me some PROOF, the internet is full of people claiming all sorts of BS. How do I know that your any different?

I want pictures, temp readings, anything at all to back up your arguement but you won't, or can't, do it.

The NEC and many manufacturers back up my argument. They have all done the work, testing and examining many different scenarios to determine what is and what is not safe. It is clearly written but you refuse to accept it.

Minimum circuit ampacity. Very clearly this is what your wire needs to be sized to, it makes no mention of breaker or fuse size because they are unrelated.

Maximum overcurrent protection. Also very clear this is the largest breaker or fuse that can be used. This makes no mention to wire size again because they are not related.

Nameplates are worded this way for a reason.

 

[eddieK]

Yep, I guess you think know better than Square D.
I just was pointing out that #10 could be used with a breaker larger than 30 amps (60 in this case).

I must be a 65 year old teenager

Why would you endorse not protecting wiring correctly?

 

[eddieK]

So then give me some PROOF, the internet is full of people claiming all sorts of BS. How do I know that your any different?

I want pictures, temp readings, anything at all to back up your arguement but you won't, or can't, do it.

The NEC and many manufacturers back up my argument. They have all done the work, testing and examining many different scenarios to determine what is and what is not safe. It is clearly written but you refuse to accept it.

Minimum circuit ampacity. Very clearly this is what your wire needs to be sized to, it makes no mention of breaker or fuse size because they are unrelated.

Maximum overcurrent protection. Also very clear this is the largest breaker or fuse that can be used. This makes no mention to wire size again because they are not related.

Nameplates are worded this way for a reason.

The manufacturers back ME up on this. Breakers protect wiring, over sizing the breaker on an air conditioning unit does not protect the wiring.

post images

This breaker and panel took the hit, not the wiring. The compressors internal overload failed in this unit, eventually the compressor went to ground and this is the damage, because the circuits were wired appropriately the wire did not fail (erupt into flame in the structure).

Breaker size and wire size are directly interconnected. A 50 amp breaker does not protect #10 wire, never has, never will.

The minimum circuit ampacity allows you to install the minimum sized breaker for that particular ampacity (load)...but the wire must be sized appropriately to that breaker. Maximum over current protection relates to the largest circuit you can install to protect the unit, again the wire must be appropriately sized for that breaker.

 

[Norcal]

We have a poster that does not own a code book, thinks the US still uses 220V, knows more then the NEC commitiees, the equipment manufacturers, the list goes on.

 

[wyliesdiesels]

Hmmm

I dont see anything in that picture related to what youre telling us.

What i do see is a number of mismatched breakers.

What brand of panel is that?

I see eaton BR, ITE, and siemens(ITE succesor)....

 

[Bert_]

The manufacturers back ME up on this. Breakers protect wiring, over sizing the breaker on an air conditioning unit does not protect the wiring.

post images

This breaker and panel took the hit, not the wiring. The compressors internal overload failed in this unit, eventually the compressor went to ground and this is the damage, because the circuits were wired appropriately the wire did not fail (erupt into flame in the structure).

Breaker size and wire size are directly interconnected. A 50 amp breaker does not protect #10 wire, never has, never will.

The minimum circuit ampacity allows you to install the minimum sized breaker for that particular ampacity (load)...but the wire must be sized appropriately to that breaker. Maximum over current protection relates to the largest circuit you can install to protect the unit, again the wire must be appropriately sized for that breaker.

I see this all the time the buss connection was poor or loose, happens even with breakers loaded to say 50%. The wiring has nothing to do with this picture.

If you won't take our word for it why don't you call up a manufacturer and ask what the minimum requirements are for wiring and breaker size?

Again we have the NEC and the manufacturer on our side. Show me pictures of failed insulation or a temp measurement on the WIRE, preferably in the middle of a run so we can be sure that a poor connection did not cause it. We are discussing the wire, not connections or anything else.

This is not hard to understand...

 

[Norcal]

The "proof" offered is nothing more then a bad breaker to aluminum bus stab connection, quite common, & none of the breakers seem to be OK for a Crouse-Hinds/Murray panel even though current Siemens/Murray are rebadged ITE breakers, same old molded case & guts.

 

[alfredeneuman]

Both GE and Sq D Homeline physically fit the bus too, but aren't listed for that panel.
With all the various brands of the breakers, I'd be curious to know what brand was removed.
Loose bus stabs to bus connections have absolutely nothing to do with the wire size.

 

[wyliesdiesels]

Heres an article written by Mike Holt on the subject.

Read it and weep!

http://www.ecmweb.com/qa/stumped-code-code-requirement-sizing-overcurrent-protection-conductors

 

[eddieK]

We have a poster that does not own a code book, thinks the US still uses 220V, knows more then the NEC commitiees, the equipment manufacturers, the list goes on.

Thanks for the insult. My customers know that the systems I put in and the circuits I wire EXCEED the minimum standards.

That's good enough for me.

Insults on a forum from people that think they know more...not so much.

 

[eddieK]

Hmmm

I dont see anything in that picture related to what youre telling us.

What i do see is a number of mismatched breakers.

What beand of panel is that?

I see eaton BR, ITE, and siemens(ITE succesor)....

First off they are not miss matched...they are the proper breakers made by differing companies...in the real world you see much worse than this AND you see HVAC systems operating into 30 years and longer, which is where doing it right in the first place and using the proper wire is so critical.

Most likely was a Challenger panel.

What you seldom see in the real world is brand new crisp installs, you see installs old enough where the ground WAS the weather sealed conduit. You see the wrong breakers in particular panels, you see where people double up on breakers. And worse.

 

[eddieK]

I see this all the time the buss connection was poor or loose, happens even with breakers loaded to say 50%. The wiring has nothing to do with this picture.

If you won't take our word for it why don't you call up a manufacturer and ask what the minimum requirements are for wiring and breaker size?

Again we have the NEC and the manufacturer on our side. Show me pictures of failed insulation or a temp measurement on the WIRE, preferably in the middle of a run so we can be sure that a poor connection did not cause it. We are discussing the wire, not connections or anything else.

This is not hard to understand...

It's not hard to understand, what is hard to understand is why people want to give homeowners bad information that could compromise their homes?

I don't need to call the manufacturers...I have attended hundreds of furthering ed classes and have established relationships with service support reps from many companies.

Every single person in this trade I know and every single electrician I work with all know that the breakers purpose is to protect the wire on that circuit it protects.

In this trade, the established safety rule for wiring home run circuits to condensing units with copper wire (without excessive runs) is 15 amp - #14 / 20 amp - #12 / 30 amp - #10 / 40 amp - #8 / 50 amp #6

We are discussing the wire here... and that was a failed compressor when I arrived on scene(Common and Run winding direct short)...pretty hard to get it to start and duplicate...

The unit had a blocked condenser coil and a clogged filter, the ambient temps that week were in excess of 110F...the units internal overload eventually did not protect from the direct short that eventually happened from the excessive heat and pressures...The panel and breaker failed...the wiring because it was not a #10 protected by a 50 amp breaker did NOT FAIL. The building did not erupt in fire because the wiring was appropriately sized.

 

[Bert_]

I think we have reached the point were any more argument is pointless. Anybody still following along can look at the facts and code articles that have already been posted and draw your own conclusions...

 

[eddieK]

Both GE and Sq D Homeline physically fit the bus too, but aren't listed for that panel.
With all the various brands of the breakers, I'd be curious to know what brand was removed.
Loose bus stabs to bus connections have absolutely nothing to do with the wire size.

The wire size is noted because IT did not fail. Had this been a #10 wire protected by a 50 amp breaker the breaker would never have over heated and failed, but the wiring would have.

It is a not book learned world out there. This particular property is a farm, lots of dirt, lots of dust and many different people working on everything.

You also have age as a factor in the real world and wear and tear...properly sizing the wire in the first place protects the system and the home when other improper things are done over the years....which happens everywhere in the real world.

The bus stab may have been not as tight as it was 20 plus years ago, but that is PRECISELY where you prefer a failure, not in the wiring in the home. That bar burned out because the connection got excessively hot, due to the compressors overload resetting and re tripping...until it did not and the winding's shorted.

 

[eddieK]

I think we have reached the point were any more argument is pointless. Anybody still following along can look at the facts and code articles that have already been posted and draw your own conclusions...

You wanted a pic and I provided it...proving that, as I stated had this been wired without the proper sized copper wire the damage would have been much worse. Notice that even the wiring connection ends didn't burn or char.

Those are the facts

It would be nice if we lived in a perfect world where people replace equipment earlier than they do, where people don't make mistakes like not tightening connections, where people keep their condenser coils clean and routinely change their system filters, where every panel is wired with the original manufacturers product...but that is not the world I work in.

I stand firmly by the established sizing for the appropriate breakers and wiring in the HVAC trade to protect my customers...and my company.

 

[kaffine]

You wanted a pic and I provided it...proving that, as I stated had this been wired without the proper sized copper wire the damage would have been much worse. Notice that even the wiring connection ends didn't burn or char.

Those are the facts

It would be nice if we lived in a perfect world where people replace equipment earlier than they do, where people don't make mistakes like not tightening connections, where people keep their condenser coils clean and routinely change their system filters, where every panel is wired with the original manufacturers product...but that is not the world I work in.

I stand firmly by the established sizing for the appropriate breakers and wiring in the HVAC trade to protect my customers...and my company.

The problem is you don't understand the actual failure with the bus bar. It was a loose connection to the breaker to bus bar that caused that over a long period of time not an overload.

NEC allows for larger breakers on AC circuits. NEC has tested and verified this is a safe practice. NEC and HVAC manufacturers with their EE have determined this is a safe and effective practice. This is established sizing for wiring for HVAC equipment and it is different than general service equipment.

You say you stand firmly by established sizing for breakers and wiring yet continue to argue with the established sizing for HVAC equipment per NEC and the manufacturers. Get and read a code book.

 

[alfredeneuman]

I stand firmly by the established sizing for the appropriate breakers and wiring in the HVAC trade to protect my customers...and my company.

The next time you "protect your customers", you ought to refer them to this thread.

5 posts in 1/2 hour.......... You mad bro?

 

[wyliesdiesels]

You wanted a pic and I provided it...proving that, as I stated had this been wired without the proper sized copper wire the damage would have been much worse. Notice that even the wiring connection ends didn't burn or char.

Those are the facts

It would be nice if we lived in a perfect world where people replace equipment earlier than they do, where people don't make mistakes like not tightening connections, where people keep their condenser coils clean and routinely change their system filters, where every panel is wired with the original manufacturers product...but that is not the world I work in.

I stand firmly by the established sizing for the appropriate breakers and wiring in the HVAC trade to protect my customers...and my company.

The pic you provided had nothing to fo with ehat you claimed it had to do with.

You clearly dont know squat about electrical.

Apparently youve never seen breakers melted at the bus stab.

Ive replaced many 15a and 20a breakers that were melted right at the bus connection and these breakers were on general use circuits. Nothing to do with motors or AC.

Do you own a code book?

 

[wyliesdiesels]

Thanks for the insult. My customers know that the systems I put in and the circuits I wire EXCEED the minimum standards.

That's good enough for me.

Insults on a forum from people that think they know more...not so much.

Lmao

Onviously your customers dont know that you dont even know basic electrical code.

And Norcal wasnt insulting you. He only quoted things youve said about yourself. So in essence, you insulted yourself.

And Norcal, a licensed electrician, knows WAY more than you, (who probably only has an EPA cert), in the electrical trade.

A browsing of the threads on here shows how much Norcal knows.

Just This one thread has showcased how little you know. But its all by your own admission.

And youve been arguing with numerous licensed electricians...hmmmm if that doesnt raise a red flag about your knowledge...

 

[eddieK]

The problem is you don't understand the actual failure with the bus bar. It was a loose connection to the breaker to bus bar that caused that over a long period of time not an overload.

NEC allows for larger breakers on AC circuits. NEC has tested and verified this is a safe practice. NEC and HVAC manufacturers with their EE have determined this is a safe and effective practice. This is established sizing for wiring for HVAC equipment and it is different than general service equipment.

You say you stand firmly by established sizing for breakers and wiring yet continue to argue with the established sizing for HVAC equipment per NEC and the manufacturers. Get and read a code book.

The problem is you were not there. I was. The failure at the bus bar was because the compressor failed, common and run winding shorted.

I am in line completely with what the manufacturers authorize.

It is not safer to under size wiring. The only examples I have been shown is for motors...A condensing unit contains a motor and a compressor, when compressors have liquid refrigerant introduced to them amperage and the associated heat ramp up rapidly, that is why it is important to properly size the wiring.

I not only follow the code I exceed the recommendations.

You can use larger breakers (max over current protection) BUT if you do, you must size the wire accordingly or that breaker is not protecting the wire.

 

[eddieK]

The next time you "protect your customers", you ought to refer them to this thread.

5 posts in 1/2 hour.......... You mad bro?

I work long hours and only spend a short time at the P/C...so when I read the comments I respond to them all and move on.

 

[eddieK]

The pic you provided had nothing to fo with ehat you claimed it had to do with.

You clearly dont know squat about electrical.

Apparently youve never seen breakers melted at the bus stab.

Ive replaced many 15a and 20a breakers that were melted right at the bus connection and these breakers were on general use circuits. Nothing to do with motors or AC.

Do you own a code book?

Yep - I own a code book and use it...Do you have tool bags and work on HVAC equipment?

So funny. The Compressor failed and the weakest link failed. That's how electrical works...and exactly why I make sure the wire size is not the weakest link. _ That just happens to be the entire emphasis of this thread...people recommending improper wiring because they think they know what they are talking about.

 

[wyliesdiesels]

Dude- are you f'ing blind?

You must have 10 electricians on here, some of whom are masters as well as engineers, telling you youre wrong and youre continuing to argue with us? And youre an HVAC tech?

Give me a f'ing break.

Have some humility and admit you dont know what the hell youre talking about which is blatantly obvious by the verbal diarrhea youve left as comments on here...

In regards to your BS about the melted bus stab. I did service work for years and saw melted bus stabs for breakers that fed general use circuits. You have absolutely no clue what youre talking about...

Have a good one. You sure did a damn good job trolling this thread... smh wned: wned2:

 

[wyliesdiesels]

Yep - I own a code book and use it...Do you have tool bags and work on HVAC equipment?

So funny. The Compressor failed and the weakest link failed. That's how electrical works...and exactly why I make sure the wire size is not the weakest link. _ That just happens to be the entire emphasis of this thread...people recommending improper wiring because they think they know what they are talking about.

So the NEC recommends improper wiring? Got it.

Now go tell that to the NFPA CMPs...

Let us know how that works out for you...

Do i have tool bags? Lmfao what does that have to do with knowing code? Nice non-sequitar... comedian must be your day job...

Youre the one who clearly doesnt know what youre talking about and there must be 10 people on here telling you this.

Now go open the code book you supposedly have and study the codes we have pointed to you...

 

[eddieK]

Lmao

Onviously your customers dont know that you dont even know basic electrical code.

And Norcal wasnt insulting you. He only quoted things youve said about yourself. So in essence, you insulted yourself.

And Norcal, a licensed electrician, knows WAY more than you, (who probably only has an EPA cert), in the electrical trade.

A browsing of the threads on here shows how much Norcal knows.

Just This one thread has showcased how little you know. But its all by your own admission.

And youve been arguing with numerous licensed electricians...hmmmm if that doesnt raise a red flag about your knowledge...

I never said I was an electrician...I am a HVAC trade professional. I do know that the breakers purpose is to protect the wire and as such they must be sized appropriately.

I wire many home run circuits for HVAC units and I service them daily.

The minimum circuit ampacity and the maximum over current protection (maximum breaker or fuse)on the nomenclature are provided by the manufacturer to help you size the circuit. You can use these two to determine the amperage of the circuit you install. Once you do that, you appropriately size the wire to the breaker.

If it says minimum circuit ampacity is 35.7 and max breaker is 50 you choose either a 40 a 45 (rare) or a 50 map circuit and you appropriately size the wire to the breaker or fuse protection...AGAIN - The breakers purpose is to protect the wire. You never just think, well, gee the built in overload will protect the circuit.

 

[eddieK]

So the NEC recommends improper wiring? Got it.

Now go tell that to the NFPA CMPs...

Let us know how that works out for you...

Do i have tool bags? Lmfao what does that have to do with knowing code? Nice non-sequitar... comedian must be your day job...

Youre the one who clearly doesnt know what youre talking about and there must be 10 people on here telling you this.

Now go open the code book you supposedly have and study the codes we have pointed to you...

Still not seen anything posted about a HVAC system specifically, a motor is not a compressor.

AND again - Breakers protect the wire.

No tools huh...well, in the real world the people that service this stuff and fully understand the dynamics do use tools while following the codes and the manufacturers requirements (which supersede the code by the way)