OSHA's crane standard sets a hard voltage ceiling specifically at the pendant pushbuttons an operator holds and presses: no more than 150 volts for AC circuits, or 300 volts for DC (29 CFR 1910.179(g)(1)(iii)). That's a separate, lower limit than the 600-volt ceiling the same regulation allows for a crane's control circuit generally (1910.179(g)(1)(ii)) — the distinction matters, because the pendant-specific limit is about the voltage actually present at the pendant pushbuttons, not the crane's overall electrical system. This piece covers what the regulation requires, how OSHA has clarified it in practice, and the related pendant requirements that come up alongside it.
The Two-Tier Voltage Rule
1910.179(g)(1) sets two different voltage limits, and they apply to two different things:
- Control circuit voltage, generally — up to 600 volts AC or DC (1910.179(g)(1)(ii)). This is the broader control-circuit limit; a separate, lower limit applies specifically at the pendant pushbuttons.
- Voltage at the pendant push-buttons specifically — no more than 150 volts AC or 300 volts DC (1910.179(g)(1)(iii)). This is the lower, separate limit, and it applies only to the voltage present at the pendant pushbuttons themselves — OSHA's own term for it.
In practice, this means a crane's control circuit can legally run at a higher voltage than what's allowed to reach the pendant — the two numbers aren't in conflict, because they're measuring voltage at two different points in the same circuit.
What Counts as “the Voltage at Pendant Push-Buttons”?
OSHA addressed this directly in a March 4, 1991 standard interpretation letter, responding to a question from Thomas W. Hagerty of Mark Crane Service, Inc. His question: does 240 volts AC satisfy the 150-volt AC maximum "if the 240 volts AC, when in a single phase condition at the pendant, is less than this requirement?" OSHA’s answer, from Patricia K. Clark, Director of the Directorate of Compliance Programs:
⚠ "This section calls for the voltage at the pendant pushbuttons not to exceed 150 volts for a.c. and 300 volts for d.c. If the voltage can be safely reduced so as never to exceed the maximum allowable voltage, then it would be considered acceptable." — OSHA Standard Interpretation, March 4, 1991
The principle: what matters is the voltage actually present at the pushbutton contacts, not the voltage supplying the crane's motors or even the broader control circuit upstream. A higher-voltage system is fine, provided that voltage is safely reduced by the time it reaches the pendant.
How Compliant Pendant Circuits Achieve This in Practice
OSHA's rule is about the result — the voltage actually present at the pushbuttons — not about which circuit architecture gets you there. In practice, crane control circuits are commonly designed so the voltage reaching the pendant pushbuttons is below the OSHA limit. A control transformer is one common way to step a higher-voltage supply down to a suitable control voltage before it reaches the pendant. For example, a crane with 480V motor power can use a lower control voltage at the pendant, provided the voltage at the pushbuttons does not exceed 150V AC or 300V DC.
Common Control Voltages at a Glance
Not a product comparison — just a quick reference for how typical control-circuit voltages stack up against the pendant-specific ceiling:
|
Voltage |
Common source |
Compliant at the pushbutton? |
|
24V AC |
Low-voltage control transformer secondary |
Yes — well under the 150V ceiling |
|
115–120V AC |
Standard control transformer secondary (most common) |
Yes — comfortably under the 150V ceiling |
|
230–240V AC |
Higher-voltage control or line circuit applied directly to the pendant |
No — exceeds the 150V AC limit |
|
480V+ AC |
Typical crane motor/line voltage |
No — must not be present at the pendant pushbuttons; the circuit must be designed so the pushbutton voltage doesn't exceed 150V AC |
The determining factor is always the voltage actually present at the pushbutton contacts — not the nameplate voltage of the crane or its motors.
Requirements That Travel With the Voltage Rule
A handful of related 1910.179(g) requirements come up alongside the voltage limit, since they govern the same pendant station:
- Cable strain relief (1910.179(g)(1)(iv)) — where multiple-conductor cable is used with a suspended pushbutton station, the station must be supported in a manner that protects the electrical conductors from strain.
- Shock protection and labeling (1910.179(g)(1)(v)) — pendant control boxes must be constructed to prevent electrical shock and clearly marked for identification of functions.
- Momentary contact (1910.179(g)(3)(vii)) — pushbuttons in pendant stations must return to the “off” position when the operator releases pressure. In practical terms, motion pushbuttons should be momentary rather than maintained.
- Floor-operated crane disconnects (1910.179(g)(5)(iii)) — for floor-operated cranes, OSHA specifies three possible disconnect arrangements (“one of the following types... shall be provided”). Two use a pendant control: an undervoltage trip operated by an emergency-stop button, or a main line contactor operated by a pendant switch or pushbutton. The third uses a nonconductive rope attached to the main disconnect switch.
- Pendant maintenance and labeling (1910.179(l)(3)(iii)(d)) — pendant control stations must be kept clean, with function labels kept legible — an inspection item, not a one-time installation requirement.
Important distinction: an emergency-stop button on a pendant is not necessarily the crane’s main disconnect. OSHA defines a "main switch" as one controlling the crane’s entire power supply (1910.179(a)(61)) and an "emergency stop switch" as one that cuts power independently of the regular operating controls (1910.179(a)(59)). In a separate 1982 interpretation addressing lockout requirements for main/emergency switches under 1910.179(l)(2)(c), OSHA confirmed that a pendant pushbutton unit operating crane motions doesn’t itself fall into either category. Applied to the disconnect arrangements above: the pendant’s role is to operate the undervoltage trip or main line contactor, not to serve as the disconnect itself — the lockable disconnect remains a separate requirement.
Terminology
- Control Circuit Voltage — the voltage supplying a crane's control circuitry generally (contactors, relays, pushbutton stations); capped at 600V AC or DC under 1910.179(g)(1)(ii) — a separate, higher limit than the pendant-specific ceiling.
- Pendant Pushbutton Station — the handheld control enclosure suspended from a crane, containing the pushbuttons an operator uses to command crane motions; specifically subject to the 150V AC / 300V DC ceiling under 1910.179(g)(1)(iii).
- Undervoltage Trip — one of three disconnect arrangements specified by OSHA for floor-operated cranes: a device that trips the main circuit breaker when triggered by an emergency-stop button in the pendant station (1910.179(g)(5)(iii)(b)).
- Momentary Contact Pushbutton — a pushbutton that stays actuated only while physically pressed, automatically returning to “off” when released; required for pendant pushbuttons controlling crane motion (1910.179(g)(3)(vii)).
- Main Line Contactor — a large, electrically-operated switch controlling the crane's main power; one of the three disconnect arrangements specified by OSHA for floor-operated cranes can be a main line contactor operated by a switch or pushbutton in the pendant station (1910.179(g)(5)(iii)(c)).
- Floor-Operated Crane — per OSHA's own definition (1910.179(a)(5)): a crane that is pendant- or nonconductive-rope-controlled by an operator on the floor or an independent platform, as opposed to a cab-operated crane.
Frequently Asked Questions
Does OSHA 1910.179 limit crane control voltage overall, or just at the pendant?
Both, at two different limits. The crane's control circuit generally can run up to 600 volts AC or DC (1910.179(g)(1)(ii)). A lower, separate limit — 150 volts AC or 300 volts DC — applies specifically at the pendant pushbuttons themselves (1910.179(g)(1)(iii)).
Can a 480-volt crane still have an OSHA-compliant pendant?
Yes. A 480V crane can have a compliant pendant circuit because the crane's motor/power voltage isn't the same thing as the voltage at the pendant pushbuttons. The control system must be designed so the voltage actually present at the pushbuttons doesn't exceed 150V AC or 300V DC. A control transformer is one common way to achieve that.
Does the 150-volt limit apply to DC pendant circuits too?
DC circuits get a separate, higher figure: 300 volts DC, versus 150 volts for AC (1910.179(g)(1)(iii)). Both are hard ceilings at the pushbuttons themselves.
What happens if a pendant pushbutton doesn't return to “off” automatically?
That's a related but separate requirement from the voltage rule: 1910.179(g)(3)(vii) requires pushbuttons in pendant stations to return to “off” when the operator releases pressure — momentary contact. It's about preventing a motion from continuing after the operator lets go, not about voltage.
Does the pendant enclosure need anything else beyond the voltage limit?
Yes. 1910.179(g)(1)(v) separately requires the pendant control box to be constructed to prevent electrical shock and clearly marked for identification of functions, and 1910.179(g)(1)(iv) requires the cable to be supported so it isn't carrying the mechanical strain of the box's weight. On an ongoing basis, 1910.179(l)(3)(iii)(d) also requires pendant stations to be kept clean with legible function labels.
How does the pendant's E-stop pushbutton relate to the crane's main disconnect?
For floor-operated cranes, OSHA specifies three possible disconnect arrangements (1910.179(g)(5)(iii)). Two use a pendant control: an undervoltage trip operated by an emergency-stop button, or a main line contactor operated by a pendant switch or pushbutton. The third uses a nonconductive rope attached to the main disconnect switch. Either way, the pendant's E-stop button isn't itself the crane's main disconnect — see the callout above.
TER Pendant Control Stations from Crane-Controls.com
Crane-Controls.com stocks TER pendant control stations across five series — Alpha, Mike, Charlie, NPA, and SPA — in single- and two-speed pushbutton configurations, with or without an integrated emergency-stop pushbutton. The switches inside these stations are rated for a broad operational range on their own — up to 250VAC on the Charlie series, for example — but that's a component capability rating, not a specification of what voltage a compliant installation should actually apply. Meeting the 150-volt AC ceiling at the pushbuttons comes down to the control transformer and circuit design used in the installation, not the pendant hardware alone. Commercial pendant installations commonly run a stepped-down control circuit (115V or 120V) well under that limit, regardless of the crane's overall power voltage.
Component rating ≠ installation voltage requirement: a switch rated for 250VAC describes what the hardware can safely handle, not what a compliant installation should actually apply at the pushbuttons. Seeing a 250VAC rating on a pendant doesn't mean it's acceptable to run 240V to it in an OSHA-covered crane application — the 150V AC ceiling still governs what's actually present at the pushbuttons, regardless of the switch's own rated capacity.
Application Support
Crane-Controls.com's technical support team can help match a pendant control station to your crane's motion and voltage requirements. Systems can be specified to support installations designed in accordance with OSHA 1910.179, CMAA, and applicable ASME B30 standards. Final electrical design and code compliance for a complete installation — including confirming the actual voltage present at the pendant pushbuttons — should be confirmed by the installing electrical contractor or engineer of record for the specific jurisdiction.
Contact: +1 888-822-2024 · info@crane-controls.com