commercial electrical load calculation worksheet pdf

Size branch-circuit conductors and the overcurrent protection device for electric heating to not less than 125% of the total heating load, including blower motors. Therefore, you must use a 30A breaker with a 10 AWG conductor.Įlectric heat. Per Table 310.16, a 10 AWG conductor at 60☌ is rated 30A. The ampacity of the conductor and overcurrent device must be at least 29A (240.4). What size branch-circuit conductor and overcurrent protection does the NEC require for a 7kW dryer rated 240V when the dryer is in a multi-family dwelling laundry room ( Fig. Table 220.18 demand factors don't apply to commercial dryers. If the dryers run continuously, you must size the conductor and protection device at 125% of the load.

Calculate the feeder demand load for dryers at 100% of the appliance rating.

Size the branch-circuit conductors and overcurrent protection device for commercial dryers to the appliance nameplate rating. Article 220 has specific requirements for most loads, including the following:ĭryers. To know if you should look in another Article, use the NEC index. For, example, round 29.5A up to 30A, but round 29.45A down to 29A.Īrticle 220 doesn't cover all specific loads. 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.

Commercial electrical load calculation worksheet pdf