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#84690 - 04/22/03 07:05 PM 430-110(c)(1)
Steve T Offline

Registered: 02/14/01
Posts: 312
Loc: Oak Park, IL, USA
Can someone help clear up what I do with the LRC once I figure it out using Tables 430-151(A) and (B) and add it to the remaining loads to to obtain the an equivalent LRC for the combined load, as paragraph #3 has me do?

430-110(c)(2) says to size the disco means at 115% of the sum of all currents at the full load condition, which I do according to the second paragraph of 430-110(c)(1).

2014 / 2011 NEC & Related Books and Study Guides
#84691 - 04/23/03 05:08 AM Re: 430-110(c)(1)
Redsy Offline

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
Uh-oh, let me try again:

The first paragraph is used to back-calculate a HORSEPOWER rating for the disconnect by utilizing the LRAs.
The second paragraph ensures that the AMPERE rating of the chosen disconnect doesn't fall below 115% of FLAs.

Ex: 460 Volt 3 phase motors

2 5HP Motors @ 46 LRA each, and 7.6 FLA each
1 10 HP Motor @ 81 LRA, and 14 FLA
Total LRA 173 Amps
Total FLA 29.2 Amps
Total 203.2 Amps

Ref Table 430.151 (B) = 30 HP rating (218 amps max.)

30 HP Disconnect is acceptable, provided it has a 33.58 amp or greater rating.
(29.2 x 115% = 33.58 amps.)

Anyone else?

[This message has been edited by Redsy (edited 04-24-2003).]


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