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Master Electrician Exam (NEC)Load CalculationsMedium

A master electrician is calculating the feeder demand load for a commercial building. The building has 10 general-purpose receptacle outlets, each rated for 15A, 120V. According to NEC 220.44, what is the minimum demand load for these receptacles?

  1. A1,000 VA
  2. B180 VA
  3. C12,000 VA
  4. D1,800 VA
Show answer & explanation

Correct answer: A. 1,000 VA

According to NEC 220.44, for receptacle loads in other than dwelling units, the demand factor is 100% for the first 10 kVA and 50% for the remainder. Each receptacle is considered to have a minimum load of 180 VA. For 10 receptacles, the total calculated load is 10 * 180 VA = 1800 VA. Since this is less than 10 kVA (10,000 VA), the demand factor is 100%, resulting in a demand load of 1800 VA.

Why the other options are wrong

  • B. This value would be incorrect as it only considers one receptacle, not the demand factor application.
  • C. This value is significantly higher than the NEC requirements for this scenario and does not reflect the correct calculation method.
  • D. This is the correct calculation: 10 receptacles * 180 VA/receptacle = 1800 VA. Since this is less than 10 kVA, the demand factor is 100%.

Commercial Receptacle Demand (NEC 220.44)

For receptacle loads in other than dwelling units, each 15A or 20A general-purpose receptacle outlet is calculated at not less than 180 VA. A demand factor is then applied based on the total calculated load.

  • Each 15A or 20A general-purpose receptacle = 180 VA
  • First 10 kVA of total calculated receptacle load = 100% demand factor
  • Remainder of total calculated receptacle load = 50% demand factor
  • Applies to commercial and industrial settings, not dwelling units

Memory trick: Commercial plugs demand 180 VA each, then a 10kVA 100% rule kicks in.

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