6.2 Cords, Panelboards, Appliances, Space Heating & Generators

Cords, Panelboards, Appliances, Space Heating & Generators

The "Equipment for General Use" area carries 15 of the 80 scored items. Beyond motors, transformers, and devices, it draws on these articles:

• 400 (flexible cords and cables) and 402 (fixture wires);
• 408 (switchboards and panelboards);
• 422 (appliances);
• 424 (fixed electric space heating); and
• 445 (generators).

These articles reward fast lookups of specific numbers, such as cord lengths, overcurrent percentages, and nameplate multipliers.

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1. Flexible Cords and Fixture Wires (Articles 400 and 402)

Cord types (Table 400.4). Type S-family cords (S, SO, ST, SOW) are extra-hard usage. SJ-family cords (SJ, SJO, SJT, junior hard service) are hard usage. Lighter types such as SPT are for light-duty appliance cords. Ampacities come from Table 400.5(A)(1) and (A)(2), not Table 310.16.

Uses permitted (400.10):

• pendants;
• wiring of luminaires;
• connection of portable luminaires, signs, or appliances;
• elevator cables;
• wiring of cranes and hoists;
• utilization equipment that is frequently interchanged;
• appliances designed for ready removal for maintenance and identified for cord connection; and
• uses specifically permitted elsewhere in the code.

Where cords are used to connect fixed appliances, the cord must have an attachment plug and be energized from a receptacle outlet (400.10(B)).

Uses not permitted (400.12). Unless specifically permitted, cords may not:

1. substitute for the fixed wiring of a structure;
2. run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors;
3. run through doorways, windows, or similar openings;
4. be attached to building surfaces (with limited exceptions);
5. be concealed by walls, floors, or ceilings, or located above suspended or dropped ceilings;
6. be installed in raceways, except as otherwise permitted; or
7. be installed where subject to physical damage.

Strain relief (400.14). Cords must be connected so tension is not transmitted to joints or terminal screws, for example with knots, tape wraps, or fittings designed for the purpose.

Fixture wires (Article 402). The minimum size is 18 AWG (402.6). Fixture wires may not be used as branch-circuit conductors (402.11).

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2. Switchboards and Panelboards (Article 408)

• Circuit directory (408.4(A)): Every circuit and circuit modification must be legibly identified as to its clear, evident, and specific purpose or use, at the panel. Spare positions with unused devices are described accordingly. "General" or "misc." does not meet the rule.
• Source marking (408.4(B)): Feeder-supplied switchboards, switchgear, and panelboards in other than one- and two-family dwellings must be permanently marked to show the device or equipment where the power supply originates.
• Phase arrangement (408.3(E)): Phases are arranged A, B, C from front to back, top to bottom, or left to right, as viewed from the front. On a 4-wire delta with a high leg, phase B is the high leg (unless meter equipment dictates otherwise).
• High-leg warning (408.3(F)): Equipment on a 4-wire delta with the midpoint of one winding grounded must be permanently field-marked "CAUTION ___ PHASE HAS ___ VOLTS TO GROUND."
• Panelboard protection (408.36): Each panelboard must be protected by an OCPD with a rating not greater than the panelboard's rating, located within or ahead of the panelboard.
• Back-fed devices (408.36(D)): Plug-in breakers that are back-fed, other than power-source output breakers covered by Article 705, must be secured by an additional fastener that requires more than a pull to release.
• Grounded conductor terminations (408.41): Each grounded (neutral) conductor needs its own terminal, not shared with another conductor, unless the terminal is identified for more than one conductor.
• EGC bar (408.40): An EGC terminal bar must be bonded to a metal panelboard cabinet, and EGCs may not land on the neutral bar except where the code permits, as at the service.
• Device count (408.54): A panelboard must have physical means to prevent installing more overcurrent devices than it was designed, rated, and listed for. The old 42-circuit limit was removed in 2008.

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3. Appliances (Article 422)

Branch-circuit rating (422.10). The branch circuit for an individual appliance must have a rating not less than the appliance's marked rating. Motor-operated appliances follow Article 430 where 422 sends you there.

Overcurrent protection for a single non-motor appliance (422.11(E)).

• Do not exceed the rating marked on the appliance.
• If no rating is marked and the appliance is rated 13.3 A or less, use not more than 20 A.
• If no rating is marked and the appliance is rated over 13.3 A, use not more than 150% of its rating, rounding up to the next standard size where 150% is not a standard size.

Storage water heaters (422.13). A fixed storage water heater of 120 gallons or less is a continuous load for sizing its branch circuit. Size at 125% of nameplate.

Worked example: A 4,500-W, 240-V water heater draws 4,500 ÷ 240 = 18.75 A. Then 18.75 × 1.25 = 23.4 A, so use a 25-A circuit. 10 AWG copper is the usual choice, because 12 AWG copper is limited to 20 A by 240.4(D).

Cord-and-plug-connected appliances (422.16(B)):

Disconnecting means (422.30–422.34).

• For a permanently connected appliance rated not over 300 VA or 1/8 hp, the branch-circuit OCPD may serve as the disconnect.
• For larger permanently connected appliances, a switch or breaker is required. It must be within sight of the appliance or lockable in the open position (110.25).
• Cord-and-plug appliances may use the plug and receptacle as the disconnect.
• A unit switch with a marked "off" position may serve in some occupancies, if another disconnect is also provided.

Ceiling fans. Paddle fans must be supported independently of the outlet box, or by a box listed for fan support, which is limited to 70 lb. Boxes listed for fans over 35 lb must be marked with the maximum weight they support (314.27(C), 422.18).

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4. Fixed Electric Space Heating (Article 424)

• Branch-circuit sizing (424.4(B)): Fixed electric space-heating equipment is a continuous load. Conductors and OCPDs are sized at 125% of the total load, including any blower motors.
• Disconnecting means (424.19): Each heater, along with its motor controllers and supplementary overcurrent devices, needs a means to disconnect all ungrounded conductors. The disconnect must be within sight or lockable. For units with supplementary overcurrent protection, the disconnect must be on the supply side of those devices.
• Thermostats as disconnects (424.20): Thermostatically controlled switching devices with a marked "off" position that open all ungrounded conductors may serve as the disconnect.
• Baseboard heaters and receptacles (424.9): Baseboard heaters may have factory-installed receptacles, which count toward the 210.52 spacing rules but may not be connected to the heater circuit. Receptacles should not be installed above baseboard heaters, because cords draped over a heater are a fire risk (210.52 Informational Note).
• Nebraska applications: Heat tape and pipe heating cables, roof and gutter deicing (Article 426), and heated livestock waterers are common in Nebraska winters. Each follows its own article and its listing instructions (110.3(B)).

Worked example: Four 2,000-W, 240-V baseboard heaters on one circuit total 8,000 W ÷ 240 V = 33.3 A. Then 33.3 × 1.25 = 41.7 A, which calls for a 45-A OCPD and conductors with at least 41.7 A of ampacity.

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5. Generators (Article 445)

• Conductor ampacity (445.13): Conductors from the generator terminals to the first OCPD must have an ampacity of at least 115% of the generator nameplate current.
• Overcurrent protection (445.12): Constant-voltage generators need overload protection by inherent design, circuit breakers, fuses, or other acceptable means.
• Disconnect and shutdown (445.18):
  • Generators need one or more disconnecting means.
  • Generators other than cord-and-plug-connected portables need an emergency shutdown for the prime mover.
  • At one- and two-family dwellings, the emergency shutdown device must be at a readily accessible location outside the dwelling.
• Portable generator GFCI (445.20): The 125-volt, single-phase, 15- and 20-ampere receptacle outlets on portable generators of 15 kW or less need listed GFCI protection integral to the generator or receptacle. The rules differ for bonded-neutral and floating-neutral generators.
• Transfer equipment: When a generator supplies a building's wiring, transfer equipment must prevent interconnection with the utility (702.5). A mechanical interlock kit listed for the panel is one common method.

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6. Common Exam Traps

• Cords as fixed wiring: Cords may not run through walls or above dropped ceilings in place of permanent wiring.
• Dishwasher cord length: The range is 3 to 6.5 feet. The disposer and range-hood range is 18 to 36 inches.
• Water heater sizing: A storage water heater of 120 gallons or less is sized at 125%.
• Generator conductors: Use 115% of nameplate current to the first OCPD, not 125%.