10.3 Appliances and Utilization Equipment (NEC Articles 422 & 424)

Why This Matters for the TX Journeyman Exam

Article 422 (Appliances), Article 424 (Fixed Electric Space Heating), and water heaters appear in content outline areas 3, 6, and the Calculations part. The exam frequently tests the disconnecting-means rule (422.31) and the water-heater branch-circuit calculation. Expect one or two calculation items per exam from this material.

Branch-Circuit Rating (NEC 422.10)

NEC 422.10(A) requires that a branch circuit supplying an appliance be rated to carry the appliance load. If the appliance is a continuous load — expected to operate 3 hours or more — the branch-circuit conductor and OCPD must be sized at 125% of the nameplate rating. If non-continuous, size at 100% of the nameplate.

A fixed storage-type water heater is treated as a continuous load per NEC 422.10(A) and must be sized at 125% of nameplate. (If your AHJ accepts an unmarked heater as non-continuous, the non-continuous alternative appears in the worked example below.)

Overcurrent Protection (NEC 422.11)

NEC 422.11 requires each appliance to be protected against overcurrent. The OCPD rating must not exceed the appliance's marked rating. For motor-driven appliances, the OCPD follows the rules of Article 430 Part X (covered in Ch7). Cord-and-plug-connected appliances are protected by the receptacle rating (15 A or 20 A).

Special Branch Circuits (NEC 422.12)

NEC 422.12 requires a separate branch circuit for certain fixed appliances:

• Electric ranges (counter-mounted or wall-mounted)
• Clothes dryers
• Water heaters
• Space-heating equipment

A 20 A branch circuit serving laundry receptacles (NEC 210.11(C)(2), covered in Ch6) is separate from the dedicated dryer circuit.

Flexible Cords for Appliances (NEC 422.16)

NEC 422.16 permits cord-and-plug connection of specific appliances when the cord:

• Is listed for the appliance type (422.16(A) general; 422.16(B) appliance-specific),
• Has a length per the article (e.g., 422.16(B)(1) freestanding electric range: minimum 3 ft, maximum 4 ft; built-in range: maximum 6 ft), and
• Terminates in a grounding-type attachment plug.

A range cord must be 4-wire (separate equipment grounding conductor, not bonded to the neutral) per NEC 250.140 — bonding details are in Ch7.

Support (NEC 422.18)

NEC 422.18 requires fixed appliances and luminaires used as heating appliances to be firmly supported independent of the attachment plug. A ceiling paddle fan must be supported by an outlet box listed for fan support (typically up to 70 lb; heavier fans require independent support).

Disconnecting Means (NEC 422.31)

NEC 422.31 sets the disconnecting means for appliances:

For a permanently connected appliance not in sight of its disconnect (e.g., attic HVAC), the breaker with a permanent lockout meets the requirement. The lockout device must be permanent — a clip-on accessory that can be removed without tools does not satisfy 422.31.

Water heater disconnect: A 4500 W water heater (over 300 W) requires a lockable disconnect within sight. A standard non-fusible safety switch rated at 30 A, 240 V is the conventional choice; a circuit breaker with a listed lockout accessory also satisfies the rule when within sight.

Nameplate (NEC 422.62)

NEC 422.62 requires every appliance to bear a nameplate showing volts, amps, and phases; motor-driven appliances must also show horsepower. The nameplate rating is the source of truth for branch-circuit and OCPD sizing.

Fixed Electric Space Heating (Article 424) and Water Heaters

Fixed electric space heating (Article 424): NEC 424.3(A) requires fixed electric space-heating equipment to be considered a continuous load — the 125% sizing rule applies. Each unit requires a separate branch circuit per 424.3(A).

Water heaters: A fixed storage-type water heater is continuous per NEC 422.10(A). Branch-circuit conductors and OCPD are sized at 125% of nameplate.

Worked Example — 4500 W, 240 V Electric Water Heater

A 4500 W, 240 V electric water heater is a common residential size. Convention used here: treat as continuous per NEC 422.10(A).

Step 1 — Full-load current:

I = P / V = 4500 W / 240 V = 18.75 A

Step 2 — Apply 125% for the continuous-load factor (NEC 422.10(A)):

18.75 A × 1.25 = 23.44 A

Step 3 — Conductor size (Table 310.16, 60°C column):

A 10 AWG Cu conductor is rated 30 A at 60°C. The 240.4(D) small-conductor rule caps 10 AWG Cu at 30 A — acceptable for a 23.44 A continuous load.

Step 4 — OCPD (NEC 240.6(A) standard ratings — 25 A and 30 A are both standard):

The next standard size up from 23.44 A is 25 A. A 25 A OCPD protects a 23.44 A continuous load. A 30 A OCPD is also commonly used when the next-standard-up allowance is applied for a continuous load.

Non-continuous alternative (if the AHJ accepts an unmarked heater as non-continuous):

• 18.75 A → 20 A OCPD with 12 AWG Cu (12 AWG capped at 20 A by 240.4(D)).

The arithmetic matches the brief's stated values; the continuous path is the NEC-consistent default.