Circuit Breaker Rating for Air Conditioner Split Unit

[TMMB]

I have a Villa with air conditioner split units and its ratings 5000 VA 1-Phase 220 V and 4000 VA 1-Phase 220 V and as per NEC 440-22 , The Proposed C.B rating as follow:

5000 VA , I= 5000/220 = 22.72 A and C.B Rating = 1.75 x 22.72 = 39.77 A , so we will use C.B Rating 40 A

4000 VA , I= 4000/220 = 18.18 A and C.B Rating = 1.75 x 18.18 = 31.81 A ,
so we will use C.B Rating 32 A

as per NEC , we use 175% and we can use 225% if the selected C.B is not sufficent for the starting current

My Q is : if i dont know the starting current for the Air Conditioner Split Unit

which factor must be used 175% or 225%.


Regards

 

[Dennis Alwon]

You need to use the nameplate rating of the units. They will tell you the minimum cir. ampacity and the max fuse.

 

[TMMB]

Thank you for reply , but WE ARE IN DESIGN STAGE WE JUST CHOOSE UNITS RATING BUT WE HAVE NOT THE UNITS CATALOGUE. IN THIS CASE WHAT FACTOR WILL BE USED.
PLEASE ADVISE

 

[Dennis Alwon]

Thank you for reply , but WE ARE IN DESIGN STAGE WE JUST CHOOSE UNITS RATING BUT WE HAVE NOT THE UNITS CATALOGUE. IN THIS CASE WHAT FACTOR WILL BE USED.
PLEASE ADVISE

I would not choose anything without knowing the info. Try this article

440.22 Application and Selection.
(A) Rating or Setting for Individual Motor-Compressor. The motor-compressor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the motor. A protective device having a rating or setting not exceeding 175 percent of the motor-compressor rated-load current or branch-circuit selection current, whichever is greater, shall be permitted, provided that, where the protection specified is not sufficient for the starting current of the motor, the rating or setting shall be permitted to be increased but shall not exceed 225 percent of the motor rated-load current or branch-circuit selection current, whichever is greater.
Exception: The rating of the branch-circuit short-circuit and ground-fault protective device shall not be required to be less than 15 amperes.

 

[TMMB]

Thank you Dennis

 

[iwire]

Hunt around for KW per BTU something close to that and you can find some ball park estimates for bidding or design purposes.

 

[Dennis Alwon]

Thank you Dennis

You're welcome

 

[zog]

I
5000 VA , I= 5000/220 = 22.72 A and C.B Rating = 1.75 x 22.72 = 39.77 A , so we will use C.B Rating 40 A

You are assuming your PF is 1.0, that won't be the case. Have a HP rating for the motor?

 

[pdemapan]

breaker must be HACR rated too