Short answer: Article 610 covers the electrical equipment and wiring of cranes, monorail hoists, hoists and their runways. Unlike most motor circuits under Article 430, crane conductor sizing starts from the motor nameplate full-load current. For one motor, the conductors carry 100 percent of its nameplate current. For several motors on one crane, the supply conductors carry the nameplate full-load current of the largest motor or group of motors for any single motion plus 50 percent of the nameplate full-load current of the next largest motor or group (NEC 610.14(E)). The runway disconnect is readily accessible and operable from the ground or floor, can be locked open, opens all ungrounded conductors at once and is within view of the runway contact conductors (NEC 610.31). The crane disconnect is rated not less than 50 percent of the combined short-time ampere rating of the motors, and not less than 75 percent of the sum of the short-time ratings of the motors for any single motion (NEC 610.33).
PSI lists Motors and Generators (5 scored NEC Knowledge and 2 scored Calculations questions) and Special Occupancies, Equipment and Conditions (6 and 3) as subject areas of the Texas Journeyman exam. PSI does not name Article 610 or say how many questions cover cranes. The Texas Journeyman Practice Pack has 1,000 original questions and 10 timed mock exams in the real two-part format, with step-by-step solutions for every calculation. Try free practice questions without signing up. Get the full pack for US$39 with one payment.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the ideas in our own words and do not reproduce NEC text. Check every rule and table value in your own 2026 NEC, and follow your supervisor and the local inspector.
How crane circuits differ from ordinary motor circuits
A crane has several motions: hoist (up and down), trolley (across the bridge) and bridge (along the runway). Each motion has one or more motors, and they rarely all run at full load together. Crane motors are also rated for short-time duty, such as 15, 30 or 60 minutes. So Article 610 has its own ampacity table for crane conductors, based on those time ratings, and its own way of adding up motor load. The general motor rules for other equipment are on NEC 430 motor circuit calculations.
| Item | General motor circuits (Article 430) | Cranes and hoists (Article 610) |
|---|---|---|
| Current used for conductor sizing | Table full-load current, in most cases | Motor nameplate full-load current |
| Several motors | 125 percent of the largest plus the others | Largest motion plus 50 percent of the next largest motion |
| Conductor ampacity | Article 310 tables | Article 610’s own table, by time rating |
The load rules
- One motor. 100 percent of the motor’s nameplate full-load current (NEC 610.14(E)).
- Several motors on one crane or hoist. The nameplate current of the largest motor or group of motors for any single crane motion, plus 50 percent of the nameplate current of the next largest motor or group (NEC 610.14(E)).
- Several cranes on one runway conductor system. Demand factors from a table in the section apply (NEC 610.14(E)).
Disconnects
- Runway disconnect. Between the runway contact conductors and the power supply, with a continuous rating not less than the load calculated under 610.14. It is readily accessible and operable from the ground or floor, can be locked in the open position, opens all ungrounded conductors at once, and is placed within view of the runway contact conductors (NEC 610.31).
- Crane or hoist disconnect. A motor circuit switch, molded case switch or circuit breaker in the leads from the runway contact conductors or other supply, lockable open. Where it is not readily accessible from the operating station, a means at the operating station opens the power circuit to all motors (NEC 610.32).
- Disconnect rating. Not less than 50 percent of the combined short-time ampere rating of the motors, and not less than 75 percent of the sum of the short-time ampere ratings of the motors for any single motion (NEC 610.33).
Overcurrent and overload protection for feeders, runway conductors, branch circuits and motors are in the overcurrent protection part of the article (NEC 610.41) (NEC 610.42) (NEC 610.43(A)). On site, lock out the runway disconnect before anyone works on the crane, under your employer’s lockout/tagout procedure.
Worked example: crane supply conductor load
A crane has a hoist motor with a nameplate full-load current of 40 A, a bridge motion driven by two motors of 12 A each, and a trolley motor of 8 A. Treat the two bridge motors as one group because they drive one motion.
- Largest single motion. Hoist 40 A. Bridge group 12 + 12 = 24 A. Trolley 8 A. The largest is the hoist, 40 A.
- Next largest motion. The bridge group, 24 A. 50 percent of 24 = 12 A.
- Load. 40 + 12 = 52 A. Select the conductor from Article 610’s ampacity table, in the column for the time rating that applies.
Worked example: disconnect rating
Using the same crane, assume the short-time ampere ratings equal the values above: 40, 24 and 8 A.
- 50 percent of the combined rating. 40 + 24 + 8 = 72 A. 72 × 0.50 = 36 A.
- 75 percent of any single motion. The largest motion is 40 A. 40 × 0.75 = 30 A.
- Result. The disconnect must meet both, so its continuous rating is not less than 36 A. Then check the device against the other requirements in Article 610.
Check yourself
- Which current is used to size crane motor conductors: table or nameplate? Nameplate full-load current.
- A hoist is 30 A, the bridge is 20 A and the trolley is 6 A. What is the supply conductor load? 30 + 50 percent of 20 = 40 A.
- Can the runway disconnect be operated from a platform reached only by a ladder? No. It is operable from the ground or floor level.
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Find Article 610 faster on exam day
NFPA 70, National Electrical Code, 2026 Edition (softcover). Write “nameplate, not table” next to 610.14 and “50 percent combined, 75 percent one motion” next to 610.33, so you do not slip into Article 430 habits on a crane question. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
Do crane motors use Table 430.250 current?
No. Article 610 sizes crane conductors from the motor nameplate full-load current.
How is the load of several crane motors calculated?
The largest motor or group for any single motion, plus 50 percent of the next largest motor or group.
Where is the crane runway disconnect located?
Readily accessible and operable from the ground or floor, lockable open, and within view of the runway contact conductors.
How is the crane disconnect sized?
Not less than 50 percent of the combined short-time ampere rating of the motors, and not less than 75 percent of the short-time ratings of the motors for any single motion.
Why do crane conductors have their own ampacity table?
Crane motors run on short-time duty ratings, so Article 610 gives ampacities by time rating instead of the continuous values in Article 310.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, Articles 430 and 610
