TL;DR

Demand Factors: NEC Article 220 multipliers accounting for non-simultaneous load operation.

By Valenke Exam Prep Team·Last updated 2026-06-02

Demand Factors

JOURNEYMAN ELECTRICIAN MASTER ELECTRICIAN

Definition

NEC Article 220 multipliers accounting for non-simultaneous load operation.

Practical Example

Electrical Calculation: Ohms law

Formula: E = I x R

Variables: E (voltage in volts), I (current in amps), R (resistance in ohms)

Example: 120V circuit with 10 ohm load: I = 120/10 = 12A

Overview

NEC Article 220 multipliers accounting for non-simultaneous load operation. Demand factor application tested on JE and ME exams.

Relevant formula: Power (3-phase) is P = 1.732 x E x I x PF. Variables: P (watts), E (line voltage), I (line current), PF (power factor).

Professional Standards

Professional standards for demand factors are established by the relevant certification body and regulatory agencies. Certified professionals must demonstrate competency through examination and maintain credentials through continuing education. Scope of practice is defined by state law and facility policy. Never perform tasks outside your authorized scope.

Troubleshooting

Troubleshooting issues related to demand factors:

Missing nail plates: Cables through studs within 1.25 inches of edge require steel plates per 300.4
Improper grounding: Bootleg ground (jumping neutral to ground at receptacle) or missing EGC
Wrong breaker size: Using 20A breaker on 14AWG circuit (max 15A per 240.4(D))

Historical Context

The National Electrical Code (NEC) was first published in 1897 and is updated every three years by the NFPA. Requirements for demand factors have evolved as electrical systems have grown more complex. GFCI protection, first required in 1971 for swimming pools, has expanded to cover nearly all wet locations. AFCI requirements, introduced in 1999 for bedrooms, now cover most habitable rooms in dwellings.

Equipment & Tools

Tools and equipment for demand factors include multimeters (for voltage, current, and resistance measurement), clamp meters (for non-contact current measurement), megohmmeter (for insulation resistance testing), and conduit benders (for EMT and rigid conduit). All test equipment must be rated for the voltage being measured. A Category III meter minimum for distribution-level work, Category IV for service entrance.

Why It Matters

Demand factor application tested on JE and ME exams.

Practice This Topic

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Frequently Asked Questions

What formulas are needed to calculate demand factors?▼

For demand factors: Box fill: Sum of: conductors x volume + clamp allowance + device allowance + EGC allowance. Variables: Per Table 314.16(B): 14AWG=2.0 cu in, 12AWG=2.25 cu in, 10AWG=2.5 cu in. Example: 4 x 12AWG + 1 device + 1 EGC = (4+2+1) x 2.25 = 15.75 cu in minimum.

What NEC articles cover demand factors?▼

For demand factors: Article 314 (Outlet, Device, Pull, and Junction Boxes): 314.16: box fill calculation each conductor = volume per Table 314.16(B). Article 250 (Grounding and Bonding): 250.66: grounding electrode conductor sizing (Table).

What are common code violations related to demand factors?▼

For demand factors: Wrong breaker size: Using 20A breaker on 14AWG circuit (max 15A per 240.4(D)). Overcrowded box: Box fill exceeds allowable volume per 314.16, common in renovation work. Improper grounding: Bootleg ground (jumping neutral to ground at receptacle) or missing EGC.