15.3 Appliances & Fixed Electric Space-Heating

Appliances on the Prov Utilization Block

Article 422 (Appliances) and Article 424 (Fixed Electric Space-Heating Equipment) are core Utilization topics for the Arkansas Journeyman exam (NEC 2023, Prov, 60 questions, 70% pass). Stems usually give watts and volts, ask for conductor or breaker size, or ask where the disconnect must be. The arithmetic is simple; the failure mode is forgetting continuous-load 125% or grabbing Table 220.55 when the question is a branch circuit.

Tab 422.10, 422.11, 422.13, 422.16, 422.30–422.35, and 424.4 / 424.19.

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Branch-Circuit Rating — 422.10

422.10(A) — for an individual appliance, the branch-circuit rating shall not be less than the marked rating of the appliance. Layer these modifiers:

• Continuous loads (loads expected to run 3 hours or more): size branch-circuit conductors not less than 125% of the continuous load per 210.19(A) (and size the OCPD accordingly under 210.20).
• Motor-operated appliances: follow Article 430 FLC/nameplate pathways as referenced.
• Household cooking appliances: the branch circuit must still meet nameplate/individual-appliance rules and any specific minimums such as 210.19(A)(3) (ranges 8¾ kW or more generally need a branch circuit rated at least 40 A). Table 220.55 demand factors apply to feeder/service load calculations, not as a free pass to undersize the range branch circuit.

422.10(B) covers circuits supplying more than one appliance or utilization load — apply 210.23 load limits (for example, cord-and-plug connected equipment not exceeding 80% of the branch-circuit rating on 15/20 A circuits, and fastened-in-place equipment limits when sharing with lighting/receptacles).

Worked example — storage water heater

A 4,500 W, 240 V storage water heater:

[ I = 4500 / 240 = 18.75\ \text{A} ]

422.13 treats fixed storage water heaters with a capacity of 120 gallons or less as a continuous load. Conductors and overcurrent protection are based on 125%:

[ 18.75 \times 1.25 = 23.44\ \text{A} ]

Select conductors rated at least 23.44 A after termination temperature limits, and an OCPD of at least that value that does not exceed conductor ampacity — commonly a 25 A or 30 A circuit depending on conductor size and 422.11 allowances. Many exam keys expect recognition of the 125% step before picking the standard breaker size.

Overcurrent Protection — 422.11

422.11 limits the maximum OCPD for appliances. Resistive heat appliances often allow next-standard-size treatment and, for certain water heaters and similar loads, an upper bound of 150% of the appliance rating when needed for nonstandard calculations — verify the exact 422.11 subsection for the appliance type in the stem. Never protect #14 copper with a 30 A breaker just because a heater “trips occasionally.”

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Flexible Cords and Disconnects

422.16 permits flexible cords only for specific appliances and conditions (in-sight length limits, strain relief, listing). A cord is not a substitute for permanent Chapter 3 wiring to a fixed appliance that the Code requires to be hard-wired.

422.30 requires each appliance to have a disconnecting means. 422.31 for permanently connected appliances generally requires the disconnect to be within sight from the appliance or to be capable of being locked in the open position in accordance with 110.25. Unit switches with a marked “off” position that disconnect all ungrounded conductors may serve as the disconnect for many appliances (422.33 / related). Cord-and-plug connected appliances may use the plug as the disconnect when the receptacle is accessible and within sight, subject to the article’s limits (422.33 / 422.34 pathways — confirm in the book for the appliance class).

Within sight (Article 100) means visible and not more than 50 feet distant. Lockable disconnects that are out of sight must meet 110.25 provisions so the equipment can be serviced safely.

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Fixed Electric Space-Heating — Article 424

Article 424 covers fixed electric space-heating equipment — baseboards, radiant panels, duct heaters, boilers, and similar — not portable plug-in heaters.

Continuous-load sizing — 424.4

Space-heating loads are continuous. Branch-circuit conductors must have an ampacity not less than 125% of the total load of the heaters (and motors, if any, as the section requires). The branch-circuit OCPD is likewise selected on that continuous-load basis (with the article’s specific overcurrent rules).

Example: Two 2,000 W, 240 V baseboard heaters on one circuit:

[ I_{nameplate} = (4000) / 240 = 16.67\ \text{A} ] [ I_{circuit} = 16.67 \times 1.25 = 20.83\ \text{A} ]

You need conductors and a protective device suitable for at least 20.83 A — a 20 A circuit is too small; move to the next compliant combination (often 25 A or 30 A with appropriately sized conductors).

Disconnecting Means — 424.19

424.19 requires a means to disconnect all fixed electric space-heating equipment, with rules for heaters with and without supplementary overcurrent devices, and for motors. Unit switches may serve as disconnects when they meet the article’s conditions. As with appliances, within-sight versus lockable remote disconnects is a frequent exam hinge.

Controllers, thermostats, and marking

Thermostats that break line current must be rated for the load; low-voltage thermostat controls feeding contactors are a different pattern — still under 424 for the power circuit. Nameplate voltage, wattage/amperage, and marking must match the supply. Mixing 208 V heaters on 240 V circuits (or the reverse) without checking the listing is a field error the exam can probe through “permitted supply voltage” language.

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Separating 422/424 From Article 220

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Arkansas Prov Takeaway

For Utilization appliance/heat items: convert W to A, apply 125% when continuous (water heaters ≤120 gal, space heat), confirm disconnect within sight or lockable, and refuse Table 220.55 when the stem is clearly a branch-circuit question.