Wire, breaker and heater sizing

Heating · Space Heaters · printed page 200 (PDF page 201)

Book index entries

Electric Heat – Wire, Breaker and Heater Sizing Wire, Breaker and Heater Sizing for Electric Heat Wood/Soil – Wire, Breaker and Heater Sizing for Electric Heat Electric Heating Systems

Text in the illustration

In some areas, a breaker on an electric heater may be larger than the wire ampacity but still be acceptable
electric heater load can be 100% of wire ampacity (15 amps X 240 volts) equals 3600 watts
A
B
C
14 gauge wire
wire ampacity is 15 amps
breaker can be 125% of the wire or heater load (15 amps X 125%) - roughly 20 amps
20 amps

Generated explanation

The illustration compares the sizing of an electric baseboard heater, two insulated conductors, and circuit breakers. The conductors are labeled 14 gauge with a wire ampacity of 15 amps. The heater annotation describes a load equal to 100% of wire ampacity, calculated as 15 amps at 240 volts, or 3600 watts. A panel containing six breakers labeled 20 amps illustrates breaker sizing at approximately 125% of the wire or heater load. The figure explicitly qualifies this arrangement as acceptable in some areas rather than presenting it as a universal sizing rule.

Components

electric baseboard heater insulated electrical conductors circuit breakers electrical panel

Materials

metal conductors electrical insulation

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