gutierrezcecilia903@gmail
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Im a bit lost on finding the min and máx ampres for 430.32(a) (1)
Finding wire size
- Thread starter gutierrezcecilia903@gmail
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- New Jersey
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- Journeyman Electrician
Are you trying to size the overloads for a motor?
- Location
- Bremerton, Washington
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- Master Electrician
The motor overload manufacturer will tell you what settings to use. Typically is 115% of motor full load current for SF 1.15. There will be chart of similar with the overloads, or on the door of the enclosure. What the code section is telling you are settings you can't exceed. I don't see a reference to Min amperes
gutierrezcecilia903@gmail
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Im learning this in school about 480 v on a 3phase and they give us a problem to do step by step and this problem has
100-hp
119-a
S.f - 1.2
I can find the FLC on the book but step 2 where my teacher wrote that I can find the máx and min on 430.32 (a) (1)
100-hp
119-a
S.f - 1.2
I can find the FLC on the book but step 2 where my teacher wrote that I can find the máx and min on 430.32 (a) (1)
iceworm
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As said, there is no minimum. Read 430.32.A.1 really carefully:
(paraphrase) Motors marked with a SF of 1.15 or greater, the overload can be no more than 125% of the nameplate current.
Now continue down to 430.32.C:
(paraphrase) If the value selected in 430.32.A.1 (125%) is not sufficient to start the motor, then for motors marked with SF of 1.15 or greater, the over load can be not greater than 140%
One could translate as, "For 1.15sf (or greater) the overload can not exceed 125% - unless that is not enough, then the overload can not exceed 140%"
Kind of goofy. But that is what it says
(paraphrase) Motors marked with a SF of 1.15 or greater, the overload can be no more than 125% of the nameplate current.
Now continue down to 430.32.C:
(paraphrase) If the value selected in 430.32.A.1 (125%) is not sufficient to start the motor, then for motors marked with SF of 1.15 or greater, the over load can be not greater than 140%
One could translate as, "For 1.15sf (or greater) the overload can not exceed 125% - unless that is not enough, then the overload can not exceed 140%"
Kind of goofy. But that is what it says
Last edited:
iceworm
Curmudgeon still using printed IEEE Color Books
- Location
- North of the 65 parallel
- Occupation
- EE (Field - as little design as possible)
Whoops, you need steps
See the paragraph right under the table in 430.32.A.1
"Modification of this value shall be permitted as provided in430.32.C"
That is the connection from the Maximum of 125% to the Maximum of 140%
See the paragraph right under the table in 430.32.A.1
"Modification of this value shall be permitted as provided in430.32.C"
That is the connection from the Maximum of 125% to the Maximum of 140%
gutierrezcecilia903@gmail
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gutierrezcecilia903@gmail
Member
- Location
- Texas
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Oh ok I see. I think I got it. Thank you. You were alot of help , now I need to figure out the wire size and I can find it on 430.22 and it has to do with 125%?
Malywr
Senior Member
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- New Jersey USA
iceworm
Curmudgeon still using printed IEEE Color Books
- Location
- North of the 65 parallel
- Occupation
- EE (Field - as little design as possible)
Yes. Read 430.22 and follow the reference to 430.6.A.1. That piece is important.
As Malywr said, it tells you to use the tables for the motor current, not the nameplate current.
For example, in this case the name plate is 109A. However, Table 430.250 lists 124A for a 100Hp (460V). So start with 124A and then apply the 125% to size the conductors.
As Malywr said, it tells you to use the tables for the motor current, not the nameplate current.
For example, in this case the name plate is 109A. However, Table 430.250 lists 124A for a 100Hp (460V). So start with 124A and then apply the 125% to size the conductors.
- 430.6.A.1 Use the table values for conductor, switches, CB or fuses (ground fault and short circuit protection)
- 430.32.A.1 Use the nameplate to size the overload
- Yes, there are a bunch of exceptions for other than standard stuff
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