Question...My air-conditioning unit is connected to a 30amp breaker at the box. The unit has a 25amp factory recommendation. There is no 25amp breaker made for my crouse-hinds box so the builder used a 30amp. Does this meet code? I was told NEC allows 30% above Recommended amperage, allowing a 30amp breaker. Is this true and does anyone know a website that tells the code allowances???
Breaker size allowances
- Thread starter noj
- Start date
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bphgravity
Senior Member
- Location
- Florida
Re: Breaker size allowances
Has a licensed and insured Electrical Contractor been involved with the installation? If not, I would strongly suggest you contact one.
Has a licensed and insured Electrical Contractor been involved with the installation? If not, I would strongly suggest you contact one.
charlie
Senior Member
- Location
- Indianapolis
Re: Breaker size allowances
This NEC? Forum is for those in the electrical and related industries. Questions of a "How-To" nature by persons not involved in the electrical industry will be removed without notice.
Your electrician will know the answer to that question. You should not be doing the work.
This NEC? Forum is for those in the electrical and related industries. Questions of a "How-To" nature by persons not involved in the electrical industry will be removed without notice.
Your electrician will know the answer to that question. You should not be doing the work.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Breaker size allowances
This is not a ?DIY? (do it yourself) situation, but rather an ?AIY? (ask it yourself). Noj is not suggesting that he (or she?) will change the breaker without professional assistance. Rather, Noj just wants to know whether the existing installation is code compliant. Let us offer the benefit of the doubt, and believe that Noj would hire a contractor, should there be a need.
For my part, I do not know enough about air conditioning systems to answer the question. I do not know, for example, whether the types of AC systems commonly used in homes have ?hermetic refrigerant motor compressors.?
Is there enough information in the question for someone to provide a simple answer?
This is not a ?DIY? (do it yourself) situation, but rather an ?AIY? (ask it yourself). Noj is not suggesting that he (or she?) will change the breaker without professional assistance. Rather, Noj just wants to know whether the existing installation is code compliant. Let us offer the benefit of the doubt, and believe that Noj would hire a contractor, should there be a need.
For my part, I do not know enough about air conditioning systems to answer the question. I do not know, for example, whether the types of AC systems commonly used in homes have ?hermetic refrigerant motor compressors.?
Is there enough information in the question for someone to provide a simple answer?
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: Breaker size allowances
There should be two values on the nameplate of the appliance.
1) Minimum circuit ampacity, and
2) Maximum fuse or breaker size.
Your breaker must be between (1) and (2).
There should be two values on the nameplate of the appliance.
1) Minimum circuit ampacity, and
2) Maximum fuse or breaker size.
Your breaker must be between (1) and (2).
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
Re: Breaker size allowances
A unit that I just wired had among others, these three pieces of information:
1) Minimum circuit ampacity [19.0 amps]
2) Minimum size HACR breaker or fuses [25 amps]
3) Maximum size HACR breaker or fuses [30 amps]
The minimum circuit ampacity is used to properly size the conductors required to power the unit. The unit was then wired with #12 THHN on a 25 amp HACR breaker.
A unit that I just wired had among others, these three pieces of information:
1) Minimum circuit ampacity [19.0 amps]
2) Minimum size HACR breaker or fuses [25 amps]
3) Maximum size HACR breaker or fuses [30 amps]
The minimum circuit ampacity is used to properly size the conductors required to power the unit. The unit was then wired with #12 THHN on a 25 amp HACR breaker.
charlie
Senior Member
- Location
- Indianapolis
Re: Breaker size allowances
NOJ, HACR stands for Heating, Air Conditioning, and Refrigeration. This is a special listing by the NRTL (Nationally Recognized Testing Laboratory such as UL) and is required if the nameplate calls for it like what was shown in Infinity's post.
NOJ, HACR stands for Heating, Air Conditioning, and Refrigeration. This is a special listing by the NRTL (Nationally Recognized Testing Laboratory such as UL) and is required if the nameplate calls for it like what was shown in Infinity's post.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Re: Breaker size allowances
In my opinion, Infinity's installation should have used #10 wire, because the breaker is above 20 amps, and I'd suggest the same to Noj: use #10, and the 30-amp breaker is fine.
In my opinion, Infinity's installation should have used #10 wire, because the breaker is above 20 amps, and I'd suggest the same to Noj: use #10, and the 30-amp breaker is fine.
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: Breaker size allowances
Roger...you're wasting money again. I would use 14 AWG for this circuit, put it on a 30 amp breaker and wash my hands of it.
[ May 05, 2005, 09:59 PM: Message edited by: ryan_618 ]
Roger...you're wasting money again. I would use 14 AWG for this circuit, put it on a 30 amp breaker and wash my hands of it.
[ May 05, 2005, 09:59 PM: Message edited by: ryan_618 ]
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
Re: Breaker size allowances
Ryan, I agree with you regarding the #14 AWG in lieu of the #12 AWG. Which section of Article 440 permits this?
Ryan, I agree with you regarding the #14 AWG in lieu of the #12 AWG. Which section of Article 440 permits this?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Re: Breaker size allowances
I did, and then went to Art. 440. It depends on your definition of "this application. "Infinity's installation may have fallen under the 125% allowance, but Noj's doesn't, at least to me.Originally posted by roger:
Larry, please expand on why you don't think the #12 is Fine
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
Re: Breaker size allowances
I think that the confusion here is that the 125% rule doesn't apply to branch circuits for listed air conditioning equipment. The manufacturer has already incorporated the extra 25% into his nameplate rating on the unit.
The unit that I mentioned stated that the minimum circuit ampacity was 19 amps. This figure already has the 125% factored in, therefore we use the 19 amps to find out what size conductors we need. I had mentioned using # 12 AWG, in actuality I agree with Ryan where as the wire used here could be #14 THHN and fused at 25 or 30 amps as required by the nameplate on the unit. This allowance appears in 240.4(G) which overrides the restrictions in 240.4(D).
I think that the confusion here is that the 125% rule doesn't apply to branch circuits for listed air conditioning equipment. The manufacturer has already incorporated the extra 25% into his nameplate rating on the unit.
The unit that I mentioned stated that the minimum circuit ampacity was 19 amps. This figure already has the 125% factored in, therefore we use the 19 amps to find out what size conductors we need. I had mentioned using # 12 AWG, in actuality I agree with Ryan where as the wire used here could be #14 THHN and fused at 25 or 30 amps as required by the nameplate on the unit. This allowance appears in 240.4(G) which overrides the restrictions in 240.4(D).
B
bthielen
Guest
Re: Breaker size allowances
One thing is certain. The way discussions get ripped apart on this site, a licesned electrician would probably feel more comfortable hiring a licensed electrician to do some work on his/her home. I don't mean to imply any negative here because it illustrates how complex and confusing the electrical codes are and how important this topic is. Any DIYer should get the idea that hiring a licensed electrical contractor is the safest bet.
Bob
One thing is certain. The way discussions get ripped apart on this site, a licesned electrician would probably feel more comfortable hiring a licensed electrician to do some work on his/her home.
I don't mean to imply any negative here because it illustrates how complex and confusing the electrical codes are and how important this topic is. Any DIYer should get the idea that hiring a licensed electrical contractor is the safest bet.Bob
busman
Senior Member
- Location
- Northern Virginia
- Occupation
- Master Electrician / Electrical Engineer
Re: Breaker size allowances
Try 440.22 in 2005 Code.
Mark
Try 440.22 in 2005 Code.
Mark
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
Re: Breaker size allowances
The reason that we can use an OCPD larger than the rating of the conductor is because the OCPD in this case, for an AC unit, is only required for short circuit protection and is sized larger to allow for the heavy inrush current on the motor start up.
[ May 06, 2005, 07:56 AM: Message edited by: infinity ]
The conductor in the example #14 THHN is rated for 20 amps according to table 310.16. It is because of 240.4(D) Small Conductors that we limit a #14 wire to 15amps unless otherwise permitted by other sections of the code. 240.4(G) references where those specific exceptions are.
The reason that we can use an OCPD larger than the rating of the conductor is because the OCPD in this case, for an AC unit, is only required for short circuit protection and is sized larger to allow for the heavy inrush current on the motor start up.
[ May 06, 2005, 07:56 AM: Message edited by: infinity ]
busman
Senior Member
- Location
- Northern Virginia
- Occupation
- Master Electrician / Electrical Engineer
Re: Breaker size allowances
Infinity said it very well. The OCPD for compressors is only for short-circuit and ground fault protection. Separate overload protection is required in Part VI of Art. 440.
Mark
Infinity said it very well. The OCPD for compressors is only for short-circuit and ground fault protection. Separate overload protection is required in Part VI of Art. 440.
Mark
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