Special Equipment

Special Equipment — NH Master Electrician Exam Study Chapter

Learning Objectives

By the end of this chapter, you will be able to:

1.1 Signs and Outline Lighting (Article 600)

Article 600 covers electric signs, outline lighting, and associated equipment. For a master electrician, the critical shift from journeyman work is understanding disconnecting means and branch-circuit sizing for continuous loads.

Disconnecting Means (600.6): Each sign must have a disconnect that opens all ungrounded conductors. For signs other than neon, the disconnect must be within sight of the sign. For neon installations, the disconnect must be within sight of the transformer or power supply (not necessarily the tubing). A master must verify that the disconnect is a listed sign controller or a standard snap switch, and that it is capable of being locked in the open position.

Branch Circuits (600.5): Sign circuits are considered continuous loads (600.5(B)). Therefore, the branch-circuit conductor ampacity must be at 125% of the sign's rated load. The overcurrent device must also be sized at 125%. Do not confuse this with the 80% rule for continuous loads on a breaker; the calculation is the same, but the code language in 600.5 explicitly requires the 125% factor on the conductor.

Ground-Fault Protection (600.10(C)): For outdoor signs within 5 ft of ground or accessible to the public, you must provide GFCI protection for personnel. This is a common inspection point for NH municipalities, especially for signs over walkways.

Exam Trap: A sign with a nameplate rating of 10 A at 120 V. The branch circuit must be rated at 12.5 A. You cannot use a 15 A breaker with 14 AWG if the ambient temperature is high? No — the trap is that you must use a 20 A circuit with 12 AWG to satisfy the 125% continuous load requirement, unless the sign is specifically marked for non-continuous operation.

1.2 Cranes and Hoists (Article 610)

Article 610 applies to cranes, hoists, monorails, and runways. This is a niche area but appears on master exams because it involves duty cycle and rating factors that differ from standard motor rules.

Conductors (610.14): The ampacity of conductors supplying a crane is based on the rated current of the motor(s) , not the branch-circuit protection. You must apply the duty cycle from Table 610.14(A). For a crane with a 5-minute rated motor, the conductor ampacity must be at least 85% of the motor's full-load current. For a 15-minute rated motor, it is 85% as well, but for a 30-minute and 60-minute rated motor, it is 90% and 100% respectively. The master must know that these percentages apply to the feeder and the branch circuit.

Overcurrent Protection (610.42): The overcurrent device for a crane motor is permitted to be higher than a standard motor. For a motor rated more than 50 hp, the maximum setting is 150% of the full-load current, but if that setting is not sufficient for starting, it can be increased to 200%. This is a significant departure from Article 430's 250% maximum for standard motors. The master supervising a crane installation must coordinate this with the disconnect rating.

Disconnecting Means (610.31): A motor-circuit switch or circuit breaker must be provided in sight of the crane disconnect. The crane disconnect itself must be capable of being locked in the open position.

Exam Trap: Do not use Table 430.52 for crane motor overcurrent protection. Article 610 has its own tables. Also, the feeder demand factor in Table 610.14(E) allows you to reduce the feeder ampacity based on the number of motors — but only if the motors are not all running at full load simultaneously.

1.3 Elevators, Dumbwaiters, Escalators, and Moving Walks (Article 620)

Article 620 is a master-level favorite because it involves multiple motors, control circuits, and emergency operation.

Feeder and Branch Circuit Conductors (620.12): The ampacity of conductors supplying a single elevator motor must be at least 125% of the motor's full-load current. For multiple elevators on one feeder, use Table 620.14 for the demand factor. The table allows a 100% demand for the first elevator, 90% for the second, 80% for the third, and 70% for the fourth and subsequent. This is a huge economic factor in high-rise work.

Overcurrent Protection (620.61): The main line disconnect for an elevator must be a fused switch or circuit breaker that opens all ungrounded conductors. The overcurrent device must be coordinated with the elevator controller's short-circuit protection. The master must verify that the elevator controller is listed and that the disconnect is not used as the sole motor overload protection.

Grounding (620.81): The elevator machine room must have a grounding terminal bar (equipment grounding conductor bus). All metal conduit, cable trays, and equipment frames must terminate to this bar. This is a specific inspection point for NH state elevator inspectors, who work alongside electrical inspectors.

Emergency Operation (620.91): For elevators with standby power, the transfer switch must be mechanical or electrical with a verified automatic operation. The master must ensure that the elevator is not connected to the generator until the generator has reached rated voltage and frequency. This requires a time-delay relay or a sequence in the transfer switch.

Exam Trap: The elevator feeder demand factor in Table 620.14 applies to motor loads only, not to the lighting, heating, or ventilation in the machine room. Those must be calculated separately.

1.4 Electric Welders (Article 630)

Article 630 covers arc welders, resistance welders, and welding cable. This is a common commercial/industrial installation.

Arc Welders (630.11): The branch-circuit conductor ampacity for an arc welder is based on the primary current rating of the welder, not the output current. You must multiply the nameplate primary current by the duty cycle factor from Table 630.11(A). For a welder with a 60% duty cycle, the factor is 0.71 (the square root of 0.6). The conductor must be rated for at least the welder's primary current multiplied by this factor.

Overcurrent Protection (630.12): The branch-circuit overcurrent device must be rated at 200% of the welder's primary current, unless the welder is rated for continuous operation, in which case it is 100%. This is a critical distinction. A standard welder with a 40 A primary current can have a 80 A breaker. This is permitted because welders are intermittent loads.

Resistance Welders (630.31): The conductor ampacity is based on the duty cycle, but the overcurrent protection can be up to 300% of the primary current. This is because resistance welders have very high inrush currents.

Welding Cable (630.42): The cable between the welder and the electrode holder must be a listed cable with a flexible stranding. It is not required to be in conduit, but it must be protected from physical damage.

Exam Trap: Do not apply the 125% continuous load factor to welders. They have their own duty-cycle tables. Also, the primary current on the nameplate is not the same as the rated load current for a motor — welders are not motors.

1.5 X-Ray Equipment (Article 660)

Article 660 applies to X-ray equipment and their control panels. This is a specialized medical/industrial area.

Disconnecting Means (660.6): A disconnecting means must be provided in the supply circuit to the X-ray equipment. It must be capable of being locked in the open position and must be located within sight of the equipment. For X-ray equipment rated more than 30 A, the disconnect must be a circuit breaker or a fused switch.

Branch Circuit Conductors (660.9): The ampacity of the branch-circuit conductors must be at least 100% of the X-ray equipment's rating, but if the equipment is rated for continuous operation (more than 1 hour), then it must be 125%. The nameplate will indicate the duty cycle.

Overcurrent Protection (660.10): The overcurrent device must be rated at 100% of the X-ray equipment's rating for non-continuous operation, and 125% for continuous. This is similar to standard continuous load rules, but note that X-ray equipment often has a high inrush due to the transformer, so the breaker must be a time-delay type.

Exam Trap: X-ray equipment is often supplied by a separately derived system (a dedicated isolation transformer) to reduce electrical noise. If so, the transformer must be grounded per Article 250.30, and the secondary conductors must have their own overcurrent protection per 240.21(C).

1.6 Induction and Dielectric Heating (Article 665)

Article 665 covers industrial heating equipment that uses electromagnetic fields. This is a rare but high-stakes installation.

Disconnecting Means (665.13): A disconnect must be provided for the heating equipment and for the associated control equipment. The disconnect must open all ungrounded conductors and be capable of being locked.

Remote Control (665.20): If the heating equipment is controlled by a remote switch, the switch must be rated for the full load of the equipment, or it must operate a contactor that is rated for the load.

Exam Trap: The high-frequency output circuits (the work coil) are not covered by Article 665 for ampacity purposes. They are covered by the manufacturer's instructions and are not considered "wiring" in the NEC sense.

1.7 Code Navigation — Where to Find It

1.8 Inspection and Supervision Points

As a master electrician in New Hampshire, you are responsible for the rough-in and final inspections. For special equipment, your checklist must include:

1.9 Common Exam Traps

1.10 Summary for the Master

Special equipment articles are not just about the equipment — they are about duty cycles, demand factors, and specific disconnecting means. A master electrician must be able to navigate from Article 600 to Article 680 quickly, applying the correct table for each situation. In New Hampshire, the state adopts the NEC 2023 without amendment, so the code is the final authority. However, local municipalities may have additional requirements for permits and inspections on signs and elevators. Always verify the local AHJ requirements before rough-in.

Remember: The exam is open book. Your speed in finding Table 610.14(A) versus Table 630.11(A) will determine your success. Practice navigating these tables until you can find them in under 30 seconds. The master license is about supervision — know what to check, where to find the rule, and how to apply it to a real-world installation.