HACR Breakers

[georgeswe]

I have had issues with a colleague for some time now and just wanted to be sure in correct. When nameplate rating on a AC unit stipulates "max fuse or breaker" my "friend" contends that you do not need fused disconnects on a AC if using HACR breaker, since most AC units have internal fuses for motor protection. My way of thinking is that the HACR rating is just the Duty rating on the breaker and the HACR stands for ?heating, air conditioning, refrigeration?. And you still need to install the fuses. and that the "or" does not mean on or another. I tell him that he has been of the field too long and is starting to forget (and he's getting old as well) But I think its mainly because hes just a hack !


Just kidding Don

 

[ryan_618]

Re: HACR Breakers

I think you are wrong. "Or" means just that...one OR the other.

 

[tx2step]

Re: HACR Breakers

I agree with Ryan. Or means or.

On the other hand, if the nameplate says just "maximum fuse size" (with no mention of a CB size) then you must have a fuse in the circuit, not just the CB at the panel. That usually requires a fusible disconnect.

[ July 26, 2005, 12:54 PM: Message edited by: tx2step ]

 

[don_resqcapt19]

Re: HACR Breakers

And if it just says breaker, then a HACR breaker is not required.
Don

 

[benaround]

Re: HACR Breakers

Well maybe he's not getting THAT old!

frank

 

[steve66]

Re: HACR Breakers

Now I'm confused.

If a "max fuse size" means a fuse, and "max breaker size" means any old breaker, then what the heck is a HACR breaker for?

Steve

 

[don_resqcapt19]

Re: HACR Breakers

then what the heck is a HACR breaker for?

For when it says "max size HACR breaker"

 

[jim dungar]

Re: HACR Breakers

Actually several years ago HACR was an additional UL listing test procedure. Now HACR is part of the standard testing procedure for UL489 breakers.

All UL489 breakers are now HACR rated. Some manufacturers still print the phrase HACR for marketing purposes only, because some people want to see it in writing. There are some UL proposals to eliminate the phrase HACR from different standards.

[ July 28, 2005, 02:36 PM: Message edited by: jim dungar ]

 

[georgeswe]

Re: HACR Breakers

ok so that being the case Jim, Does that mean that a breaker not labeled HACR would still work in this situation? I should probablyu contact the manufaturer. And if so then I should be ok to install non-fused disconnects at the unit.

thanks I'll look into it.

 

[milwaukeesteve]

Re: HACR Breakers

steve66
Max breaker size refers to the Max HACR breaker, not just any old breaker.
Just any old breaker does not allow for enough time at a high rate of current (above the actual rating) to allow for the start up of motors, more secifically, those motors related to compressors.
HACR breakers are actually INVERSE TIME breakers. Definition is in article 100.
Just any old breakers are INSTANTANEOUS TRIP breakers. Definition is in article 100.


440.22 This is for SHORT CIRCUIT and GROUND FAULT "A Protective Device" shall be size no more than 175% of the rated load current.
This would be your 'just any old breaker', HOWEVER, you would still need overcurrent/overload protection.


440.52 This is for OVERCURRENT/OVERLOAD protection.

(3) a fuse or inverse time breaker (HACR or time delay fuse) responsive to the motor current, which shall also serve as SCGF protection, rated at not more than 125%...

 

[jim dungar]

Re: HACR Breakers

Steve,

All "standard" breakers are inverse time delay.
Special application breakers like those found in combination starters or the little pushbutton ones found in plug strips, are often instantaneous types.

The old HACR rating had nothing to do with inrush currents. It had to do with the multiple motors found in heating, air conditioning, and refrigeration equipment. Multiple motors have always required special treatment in the NEC, 430.53 and 440.22(B) are some examples.

The NEC never uses the phrase HACR. The handbook commentary for 440.21 is incorrect in saying listed devices "are marked" HACR the correct phrase is "maybe marked".

 

[infinity]

Re: HACR Breakers

All "standard" breakers are inverse time delay.
Special application breakers like those found in combination starters or the little pushbutton ones found in plug strips, are often instantaneous types

I'm with Jim on this one. All standard breakers are inverse time breakers. That includes the $3 ones at Big Orange.

 

[templdl]

Re: HACR Breakers

As far as I can tell there is really no difference in a pre HACR breakers and HACR rated breakers. The time current curve have not changed between them as I can tell. I don't know what foofoo dust they are sprinkled with to make them magical HACR breakers other than a common breaker was submitted to UL for testing to meet HACR standards and be allowed to be labeled HACR.
"SWD", switching duty breakers have to meet UL testing requirements for fluorescent lamp loads which includes operations and temperature rise.
HID breaker are tested in a similar fashion except that contacts are a problem which necessitated a heavier duty contact to be used. This may simply involve using a 50a type breaker with heavier contacts and calibrated 15a.
It has been of my experience that residential breaker are manufactured in (30 groups, 15-30a, 31-70a, and 71-100a. In other word a 15a and a 30 breaker are exactly the same except for the thermal calibration but mag cal. is the same. A 40 and 50a breaker have the same mag. cal.
Yes, the standard UL489 listed breaker has an inverse time element but also has a magnetic, instantaneous element that will trip the breaker instantaneously in response to short circuits.
Th instantaneousness magnetic elements are kind of crude and are designed to trip the breaker from anywhere from 6-7x the breaker rating for standard breakers to 10x and even more for "high mag" residential breakers . At one time one manufacturer had a "standard" breaker and then a "low mag" 6-7x breaker. Today I think the manufacturers may be on the same page with the standard and high mag rating. But it always wasn't apples to apples.
The magnetic pickups of industrial breakers are 10x the rating of the breaker with a +-20% calibration range. Again, its a relatively crude clapper type design similar to the residential breakers.
The UL 489 "reverse UR" motor circuit protector mag only breaker uses an actual solenoid for breaker frames up to 150a. The wire used to wind the solenoid is small in the lower ampere breaker ratings and larger as the frame ratings get higher. The small wire is needed for the amp turns for the solenoid to respond but can be fried if the rating of the breaker is exceeded by very much.
Larger mag only breakers commonly use a simple clapper design. It is often overlooked that the mag only beaker can not protect itself form overcurrent and is often destroyed when there is an attempt to "test" it.

 

[sandsnow]

Re: HACR Breakers

Originally posted by don_resqcapt19:
And if it just says breaker, then a HACR breaker is not required.
Don

Don is correct, but watch out for a nameplate that says "....or circuit breaker*"

The asterisk will refer you down to the bottom of the nameplate where it will call out HACR type.

It would be nice if the HACR thing was eliminated.

 

[ryan_618]

Re: HACR Breakers

I thought there was some sort of change about the whole "HACR" thing in the 2005 NEC. I don't remember where it was, or exactly what it was though

 

[templdl]

Re: HACR Breakers

Correction. One slipped by when editting my post. Its (3)groups, 15-30a, 31-70a, and 71-100a. Not 30!

 

[milwaukeesteve]

Re: HACR Breakers

HACR breakers were designed specifically for the refrigeration genre of circuits because of its ability to allow for the large inrush of current, and the extended delay on that inrush, due to the nature of motor/compressors.
That is also why there is a separate section in the code book for refrigeration, since the loads and demands on circuits is so different than normal branch circuits and also other motors.

That is why 440.22 (sizing SCGF protection) states that it the rating shall be no more than 175%, YET, continues on and states that if that does not allow the motor to start, the size can be increased to 225%

If you use a non HACR/Inverse time breaker, those delays and pickups are not there to allow for startup. That is why non HACR breakers need to be supplemented with OverCurrent protection, since it is only SCGF.

Yes, most of the breakers you can by at the HO depot are HACR rated already. But not all breakers you are going to use are going to be that.

Edited: spelling errors

[ July 29, 2005, 03:10 PM: Message edited by: milwaukeesteve ]

 

[jim dungar]

Re: HACR Breakers

HACR breakers never had special trip characteristics. This is an old wives tale.

UL no longer has a seperate test for HACR breakers. ALL (even 1 pole) UL489 breakers are now automatically suitable for HACR applications.

This is an excerpt from a Square D publication.

"A great number of circuit breakers were investigated by UL using the special HACR testing. It was found that all circuit breakers that passed the normal UL 489 tests also passed the special HACR testing without a special design. As a result, UL 489 has been revised to recognize that all circuit breakers that satisfy the construction and test requirements for UL 489 Listing are also suitable for HACR applications.
Paragraph 7.7 of the 9th edition of UL 489 grants HACR listing to all UL 489 Listed circuit breakers. There is no longer a requirement for special testing."

edit phrasing

[ July 29, 2005, 05:17 PM: Message edited by: jim dungar ]