AC Conductors and Breakers

Status
Not open for further replies.
C

cirelo132

Member
Hey folks, I have a question.

I have an Air Handler with a nameplate that has:
Min Ckt Ampacity: 17.6 A
Maximum Fuse or HACR Type Circuit Breaker: 30 A

Is it ok to put a #12 AWG MC Cable with a 25A breaker to this?

How about:
Min Ckt Ampacity: 29.8 A
Maximum Fuse or HACR Type Circuit Breaker: 50 A

with a #10 AWG and a 45 A breaker?

It seems like this configuration should be ok, since it follows the nameplate, but which part of the code allows this? It seems like it violates the "#12 with a 20 A breaker" rule from 310.16.

Also, FYI, this is residential.

Thanks in advance for the help!
 
Last edited:
Also take a look at Part III of Article 440 for the branch circuit short circuit and ground fault protection requirements for A/C units and Part IV for the branch circuit conductors.

Chris
 
Since the OP said it was an air handler, wouldn't it be Art. 430. My take is that Art. 440 is just for components with a Hermetic compressor.

Mark
 
busman said:
Since the OP said it was an air handler, wouldn't it be Art. 430. My take is that Art. 440 is just for components with a Hermetic compressor.

Mark
Click to expand...

You are right I read the title AC conductors and breakers and thought of an A/C unit not an air handler.

Chris
 
I have never seen an air handler with nameplate information like that so I am assuming that it is an A/C unit.
In the first example a #14 with a 30 amp OCPD would comply with the code rules. In the second a #10 with a 50 amp breaker would comply. Using breakers smaller than the maximum permitted on the nameplate sometimes results in "start-up" tripping.
 
cirelo132 said:
. . . HACR Type Circuit Breaker: . . .
Click to expand...
You are not permitted to use a standard circuit breaker but you must use a HACR (heating, air-conditioning, refrigeration) circuit breaker. :smile:
 
charlie said:
You are not permitted to use a standard circuit breaker but you must use a HACR (heating, air-conditioning, refrigeration) circuit breaker. :smile:
Click to expand...

Aren't pretty much all the standard breakers made today HACR rated?

Chris
 
HACR Circuit Breakers

HACR Circuit Breakers

raider1 said:
Aren't pretty much all the standard breakers made today HACR rated?
Click to expand...

You know, I keep hearing that but this is from the 2007 edition of the UL White book:
Circuit breakers investigated for use with heating, air conditioning and refrigeration equipment comprising multi-motor or combination loads are marked ??HACR TYPE,?? in conjunction with the Listing Mark. Such circuit breakers are suitable for use with heating, air conditioning and refrigerating equipment marked for use with HACR type circuit breakers. Use of these circuit breakers with heating, air conditioning and refrigerating equipment is limited to installations where the equipment is marked as suitable for use with any properly sized circuit breaker, or is marked for use with a HACR type circuit breaker, or is not limited by any marking as to the type of branch circuit, short-circuit and ground-fault protective device.

​
I have also found the following statement in several places concerning air conditioning equipment and heating equipment:
Where the marking specifies fuses or ??HACR Type?? Circuit Breakers, the circuit is intended to be protected only by the type of protective device specified.

​
I don't know what the manufacturers are doing but this is what UL says. :smile:
 
Status
Not open for further replies.
Top