CET Elevator cheat sheet

Elevator work is governed in the US by ASME A17.1 (safety code for elevators and escalators) and in Canada by CSA B44; both are adopted into law by state, provincial, or local jurisdictions rather than being self-enforcing.

OSHA 29 CFR 1910.147 (lockout/tagout) requires a written energy-control program, machine-specific procedures, lockout hardware, and verification of zero energy before servicing; elevator controllers, disconnects, and pit sump pumps can each be separate energy sources.

A pit is a permit-required confined space unless the employer documents that hazards (falling, electrical, sump, entrapment) are eliminated; entry then follows 29 CFR 1910.146 with attendant, atmospheric testing, and rescue plan.

Fall protection: 29 CFR 1926 Subpart M applies at 6 ft (1.8 m) or more in construction; personal fall-arrest systems require a full-body harness, shock-absorbing lanyard, anchorage rated 5,000 lb (22.2 kN) per worker, and prompt rescue.

Barricades and warning signs are required at every open hoistway entrance, open pit, and open machinery space; the 2017+ A17.1 requires hoistway access doors to be self-closing and self-locking.

Arc flash: NFPA 70E requires an incident-energy analysis or table-based PPE selection; typical elevator controller work at 480 V three-phase falls in PPE Category 2 or higher unless the label states otherwise.

Two-person rule / communication: maintenance in the pit or on top of the car should have a means of communication to the landing, and a car-top stop switch within reach of the working platform.

Bloodborne pathogens (29 CFR 1910.1030) and first aid apply because entrapment rescues may involve injured passengers; only trained personnel perform manual hoistway evacuation with the car at a landing.

Traction drive: an electric motor drives a sheave; the car and counterweight are suspended by ropes or coated steel belts. Counterweight is sized to roughly car weight plus 40-50% of rated load, so the machine works least at half load.

Geared machines use a worm gear (typical rope speed up to ~200-350 fpm); gearless machines use a direct-drive PM synchronous motor with a disc brake and reach 500-2000+ fpm.

Hydraulic drive: a power unit (tank, pump, motor, valve) pushes oil to a jack (single-stage or telescopic) to raise the car; lowering is by gravity through the valve. Typical speeds 50-200 fpm, travel limited by jack length.

Safety gear is a car-mounted device that grips the guide rails on overspeed; it is tripped by the governor (mechanical centrifugal or electronic) at typically 115% of rated speed, with governor trip and safety-setting speeds set by code tables.

Buffers absorb kinetic energy at the pit: oil buffers for speeds above 200 fpm (or per code), spring/polyurethane buffers for lower speeds; buffer stroke and oil level are code-inspected items.

Door operator: car door and landing doors are coupled by a vane/clutch; landing doors have a mechanical lock plus an electrical contact that must prove locked before the car can run, except in the leveling zone.

Suspension: A17.1 requires a minimum number of ropes (typically 3 for traction) and rope-tension equalization; each rope's factor of safety is calculated from breaking strength versus static load.

Controller types: relay logic (legacy), PLC/relay hybrid, and microprocessor/software-based (e.g., destination dispatch). Regenerative drives return energy to the building or a resistor bank.

Plumb and align: guide rails are set to plumb within code tolerance (commonly 1/8 in per 100 ft or tighter per manufacturer), with rail brackets and fishplates torqued to spec; car and counterweight rail alignment determines ride quality.

Rope/ belt inspection: look for broken wires (code rejection counts per lay length), diameter reduction, corrosion, kinks, and uneven tension; ropes are replaced as a set, never singly.

Maintenance intervals: routine lubrication of guide rails, rope sheaves, and hydraulic oil checks; brake gap, pad wear, and coil resistance are measured against manufacturer limits at each PM.

Hydraulic system: check oil level and temperature, valve for creep (car drift from level), jack for leaks, and the pressure-relief valve setting; oil cooler and heater keep viscosity in range.

Door system is the highest-failure subsystem: check gibs, rollers, clutch/vane engagement, close force (limited to ~30 lbf / 135 N kinetic energy limits per code), reopen device, and door detector (light curtain or 3D sensor).

Load test and inspection: test at 125% of rated load for rated speed and braking; annual test includes safety gear, governor, buffers, and emergency brake; Category 1 and Category 5 tests per A17.2 (or CSA B44) schedule.

Electrical safety during PM: verify disconnect open and locked, test for voltage, and confirm the car is on the machine-room stop or pit stop before reaching into the hoistway.

Documentation: log every repair, test, and code-required inspection; keep records of rope/ belt replacement, brake adjustments, and governor trip tests for the equipment file.

ASME A17.1/CSA B44 is the model safety code; A17.2 covers inspection, A17.3 covers existing elevators, A17.5 covers electrical equipment, and A17.6 covers suspension means. The AHJ adopts and enforces the edition in force.

Periodic inspection categories (A17.2): Category 1 (annual, routine), Category 3 (every 3 years, more thorough), Category 5 (every 5 years, includes load test and safety test). Jurisdictions may vary the schedule.

Maintenance control program: A17.1 requires a documented maintenance program (MCP) for each unit, with tasks, frequencies, and records available to the inspector.

Accessibility: ASME A17.1 Section 2.27 and ICC A117.1 set car size, door clear width, hall call height, braille/tactile signage, two-way communication, and audible/visual signals for accessibility.

Elevator licensing: most states require a licensed elevator contractor and licensed mechanics/technicians; work outside license scope is a violation even if the installation is code-compliant.

Alterations vs. repairs: an alteration (e.g., changing controller, door operator type, or speed) triggers code compliance for the altered component and often a permit; a repair restores original function.

Electrical code interface: NFPA 70 (NEC) Article 620 covers elevator feeders, disconnects, lighting, and the machine room; the disconnect must be lockable and within sight of the controller.

Fire recall: ASME A17.1/NFPA 72 require Phase I recall on smoke detection in lobbies, machine rooms, and hoistways, and Phase II (in-car) operation for firefighter service, with keyed switches and status indicators.

Fault isolation order: verify power at the disconnect, then control transformer, then door lock circuit, then safety circuit (governor, pit, car top, buffers), then run command; the safety chain is series-wired so one open contact stops the car.

Door lock circuit: measure voltage across each lock contact; a bad contact shows full voltage across it while the circuit is open. Door operator faults often present as intermittent 'door open' or 'not leveling' errors.

Safety chain: use the controller's fault log or a meter to walk the chain; common opens are pit stop switch, car-top stop, governor switch, and final limit. Never jumper a safety device except for documented, supervised testing.

Motor/ drive: check three-phase voltage balance, insulation resistance (megger) to ground, encoder feedback, and brake pick/release. A dragging brake causes overheating and overload trips.

VFD faults: overvoltage on deceleration (regeneration), undervoltage on start (supply sag), overcurrent (mechanical bind or short), and ground fault. Read the drive fault code before resetting.

Hydraulic faults: car won't hold level (valve leak or check valve), slow up (pump wear or low oil), noisy operation (air in system, cavitation), and overheating (cooler or relief valve passing).

Mechanical: vibration and noise from misaligned rails, worn guide shoes, rope tension imbalance, or sheave bearing wear; a car that rides rough only at certain floors points to rail joints or roller guides.

Use a systematic record: note floor position, load, direction, and time of fault; compare with the controller event log; reproduce under the same conditions before replacing parts.