If the extra is 0.49 or less, round down to the next whole number. When the ampere calculation exceeds a whole number by 0.5 or more, round up to the next whole number. Rounding - Refer to 200.2(B) to end the rounding mystery.Thus when you calculate branch-circuit, feeder, and service loads, you must use a nominal system voltage of 120V, 120/240V, 208Y/120V, 240V, 347V, 480Y/277V, 480V, 600Y/347V, or 600V unless otherwise specified (220.2) ( Fig. Voltage - The voltage to use for your calculations depends on the system design voltage.Two items associated with this type of calculation repeatedly need clarification: 210 says about continuous loads, and understand the overcurrent protection requirements set forth in Art. For example, you must know the definitions in Art. The National Electrical Code (NEC) covers commercial calculations in Art. Note: This article is based on the 2002 NEC.Įven if you work with stamped drawings, you'll eventually need to do commercial load calculations in the field or on a licensing exam. If you’d like to see updated information on this topic, please check out this recently published article, Load Calculations - Part 1. Thank you for visiting one of our most popular classic articles.
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