8.3 EV Charging, Signs, Welders, Elevators & Fire Pumps (Articles 625, 600, 630, 620, 695)

EV Charging, Signs, Welders, Elevators & Fire Pumps (Articles 625, 600, 630, 620, 695)

Outside pools and solar PV, the "Special Equipment" items on the exam usually come from five articles. Each has one or two signature numbers:

• the 125% EV charging circuit;
• the 20-ampere sign outlet;
• the welder duty-cycle multiplier;
• the elevator disconnect; and
• the fire pump's locked-rotor and 15% voltage-drop rules.

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1. Electric Vehicle Power Transfer Systems (Article 625)

Worked example: A 48-A Level 2 charger is a continuous load. 48 × 1.25 = 60 A, so it needs a 60-A breaker. The conductors need at least 60 A of ampacity after any adjustment: 6 AWG copper (65 A in the 75°C column), provided both terminations are rated 75°C. Otherwise use the 60°C column, where 6 AWG copper is only 55 A. The disconnect rule of 625.43 does not apply because 60 A is not more than 60 A and 240 V single-phase is 120 V to ground.

Bidirectional EVSE that can export power (vehicle-to-home or vehicle-to-grid) is also an interconnected power source under Article 705.

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2. Electric Signs and Outline Lighting (Article 600)

• Required sign outlet (600.5(A)): Each commercial building and each commercial occupancy accessible to pedestrians needs at least one sign outlet in an accessible location at each entrance to each tenant space. It must be supplied by a branch circuit rated at least 20 A that supplies no other load. Service hallways and corridors don't count as pedestrian-accessible.
• Branch-circuit rating limits (600.5(B)): Circuits supplying neon tubing installations may not exceed 30 A. Circuits supplying other signs and outline lighting (incandescent, fluorescent, HID, and similar) may not exceed 20 A.
• Disconnect (600.6): Each sign or outline lighting system needs an externally operable switch or breaker that opens all ungrounded conductors and controls no other load. It must be within sight of the sign, or lockable open if not within sight.
• Listing and marking (600.3, 600.4): Signs and outline lighting must be listed and installed per their instructions. Field-installed skeleton tubing and retrofit kits have their own listing rules.
• Grounding and bonding (600.7): Metal sign parts are bonded. Flexible metal conduit may serve as a bonding means under specific conditions, such as remote metal parts of neon secondary circuits.

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3. Electric Welders (Article 630)

Supply conductors for an individual arc welder (630.11(A)). Use the nameplate I1eff if it is given. Otherwise, multiply the rated primary current I1max by the duty-cycle multiplier from Table 630.11(A):

Groups of welders (630.11(B)). Use the individual values from (A) and add:

• 100% of the two largest welders;
• 85% of the third largest;
• 70% of the fourth largest; and
• 60% of all the rest.

Overcurrent protection (630.12):

• Protection for the welder may be rated up to 200% of I1max.
• Protection for the supply conductors may be rated up to 200% of the conductor ampacity.
• Each welder needs a disconnect unless one is built in (630.13).

Worked example: A transformer arc welder has I1max of 50 A and a 50% duty cycle, with no I1eff marked. Minimum conductor ampacity = 50 × 0.71 = 35.5 A. Maximum welder OCPD = 2.00 × 50 = 100 A. Maximum OCPD for conductors with 40 A of ampacity is 2.00 × 40 = 80 A. The conductor limit governs, so use 80 A or less.

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4. Elevators, Escalators and Similar Equipment (Article 620)

• Main disconnect (620.51): Each elevator has a single means of disconnecting all ungrounded main power supply conductors. It is an enclosed, externally operable fused switch or circuit breaker, lockable open, and located where it is readily accessible to qualified persons. It must not disconnect the car lighting, receptacle, and ventilation circuits.
• Separate branch circuits: Car lighting, receptacles, ventilation, and alarm (620.22), machine room and control room lighting and receptacles (620.23), and hoistway pit lighting and receptacles (620.24) each have their own required branch circuits.
• Switches and receptacles: The lighting switch for machine rooms and pits must be at the point of entry. At least one 125-V duplex receptacle is required in machine rooms and pits.
• GFCI (620.6): Required for 125-V, 15- and 20-A receptacles in pits, hoistways, on car tops, and in machinery spaces. A single receptacle for a permanently installed sump pump is excepted.
• Nebraska law note: Under Neb. Rev. Stat. § 81-2121(3), the State Electrical Act does not cover elevator work beyond the controller terminals. Elevator contractor licensing is separate. Electricians still install the feeder, disconnect, and the 620 branch circuits.

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5. Fire Pumps (Article 695)

The design goal reverses the usual rule: keep the pump running even if the motor is damaged, because the building is on fire.

Why locked-rotor? If the fire pump breaker were sized like an ordinary motor circuit, a stalled or overloaded pump could trip it during a fire. Article 695 accepts damage to the motor rather than lose the pump.

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6. Common Exam Traps

• EV disconnect threshold: More than 60 A, or more than 150 V to ground.
• Sign outlet: A 20-A circuit that serves no other load, at each tenant entrance.
• Welders in a group: The two largest are counted at 100%.
• Fire pump starting voltage drop: 15% at the controller. The general 3% and 5% voltage-drop recommendations are only informational notes.
• Elevator disconnect: It may not kill the car lights.