MI Elevator Mechanic cheat sheet

A17.1/B44 is the design, construction, installation, and alteration code; A17.2 covers inspection, A17.3 covers existing installations, and A17.5 covers electrical equipment.

Minimum rated load for passenger elevators is based on car floor area: 50 lb per square foot of net floor area is the lower bound used with the code's area-load table.

Clear inside car height must be at least 7 ft (2.13 m); car doors must be at least 6 ft 8 in (2.03 m) high and provide an unobstructed clear opening.

Required car lighting: at least 2 ft-candles (21.5 lux) at the car floor with doors closed, and emergency lighting of at least 5 ft-candles for 4 hours at the car threshold.

Escalator: maximum rise per unit is 60 ft (18.3 m); nominal speed may not exceed 125 ft/min (0.63 m/s) where the rise exceeds 20 ft, and 100 ft/min where rise is 20 ft or less.

Escalator rated load is computed as 2 persons per 16 in (400 mm) of nominal width per step band segment; the code assumes 50% occupancy for capacity-based calculations.

Escalator clearance: minimum 7 ft (2.13 m) vertical clearance above the step band to any obstruction, and 2 ft 4 in (711 mm) between handrail centerlines minimum.

Machine-room and control-space access doors must be self-closing and self-locking, open outward, and be at least 30 in (762 mm) wide by 6 ft 8 in (2.03 m) high.

Ohm's law: E = I x R; power in a DC or resistive circuit: P = E x I = I^2 R = E^2 / R.

Three-phase power: P (watts) = 1.732 x E_line x I_line x power factor; synchronous speed N = 120f / P where P is pole count.

Motor slip: percent slip = (N_sync - N_measured) / N_sync x 100; typical NEMA Design B induction motors run 2-4% slip at rated load.

Across-the-line starting draws roughly 6x nameplate full-load current; wye-delta and reduced-voltage starters lower inrush at the cost of torque.

A dynamic braking resistor converts motor kinetic energy to heat during deceleration; the resistor's duty rating, not its ohmic value alone, sets its thermal limit.

NEMA contactor sizing is by horsepower rating and utilization category (AC-3 for squirrel-cage motor starting), not just by amp rating.

A ground-fault circuit must trip at 5 mA +/- 1 mA for personnel protection; equipment GFCI in elevator circuits is typically set at 30 mA or higher per code.

Variable-frequency drives require shielded motor cable with the shield grounded at the drive end; long cable runs cause reflected-wave overvoltage at the motor terminals.

Traction ratio = total load on the sheave divided by the lesser rope tension; 1:1 roping has a ratio of 1, 2:1 has 2, and higher ratios reduce rope load but double rope travel.

Suspension rope safety factor: at least 12 for traction elevators with rated speed above 50 ft/min, and at least 16 for drum-type machines per A17.1.

Minimum number of suspension ropes is 3 for traction elevators; each rope must be independently terminated and equalized.

Rope construction for elevators is typically 6x19 or 8x19 seale independent wire rope core (IWRC); fiber-core ropes are not permitted for traction suspension.

Sheave-to-rope diameter ratio must be at least 40:1 for traction machines; smaller ratios accelerate fatigue and require more frequent inspection.

Rope wear rejection: replace when diameter reduction exceeds the code limit (roughly 3% below nominal for 6-8 strand ropes) or when broken wires in one lay exceed the A17.1 table.

Counterweight equals car weight plus approximately 40-50% of rated load, balancing the system so the machine sees near-equal tension up and down.

Guide rail alignment tolerance is typically 1/8 in (3 mm) over 5 ft; misalignment causes roller or gib wear and car sway.

Governor tripping speed is set between 115% and 140% of rated speed for car governors; the tripping speed must not exceed the value in the A17.1 table for the rated speed.

The safety (car or counterweight) must stop the car within the code's deceleration limit; the governor tripping speed and safety setting combine to produce this.

Instantaneous safeties are permitted only below the code's speed threshold (typically 200 ft/min for cars); above that, type A or type B progressive safeties are required.

The governor rope must be at least 1/4 in (6.4 mm) diameter and must be tensioned so the governor operates before the car reaches the pit buffers.

Buffers: oil buffers are required for rated speeds above 200 ft/min; spring buffers are permitted below that. Buffer stroke must match the code table for rated speed.

Brake torque must hold 125% of rated load; the brake is set by spring and released by magnet or hydraulic pressure, so loss of power applies the brake.

The brake must be a friction type with a self-engaging design; a brake that depends on electrical or hydraulic power to set is not permitted.

Final limit switches must be independent of the normal limit switches and must open the power circuit before the car or counterweight reaches the buffer.

Hydraulic elevators are limited to a maximum travel of about 60 ft (18.3 m) for in-ground cylinders and 50 ft (15.2 m) for holeless telescoping cylinders.

Rated speed of a hydraulic elevator is set by pump displacement and plunger area: v = Q / A, so doubling plunger area halves speed at the same flow.

The relief valve must be set to open at no more than 150% of the full-load pressure and must be tested with the car at rest and loaded.

The check valve holds the car when the pump stops; the lowering valve controls descent. Both must be tested for leakage and response time.

The pressure switch and rupture valve protect against line failure; the rupture valve must close when flow exceeds the design limit, stopping the car.

Hydraulic fluid temperature affects viscosity and speed; typical operating range is 60-140 F, and low temperature raises pressure and slows descent.

The cylinder must have a means to detect and remove air; trapped air causes spongy ride and can allow the car to drop when the pump stops.

The pit must have a drain or sump and the cylinder must be protected against corrosion; a failed cylinder casing leaks oil into the pit and is a code violation.

Periodic inspection intervals are set by the authority having jurisdiction; A17.2 inspection procedures cover car, machine room, pit, and hoistway, in that order.

Annual tests include: safety device test with rated load, governor tripping speed, buffer test, brake test, and relief valve test on hydraulic units.

Five-year tests include: safety device test at 125% of rated load and a full-load test of the machine and brake.

The governor tripping speed is measured with a tachometer at the governor or by the rope speed; record the measured speed and compare to the A17.1 table.

The safety test is performed by tripping the governor and observing the car stop; measure the stopping distance and check for even engagement of both safety blocks.

Escalator inspection: check step-to-skirt clearance (not more than 3/16 in per side), comb teeth engagement, handrail speed, and the stop switch operation.

Maintenance records must be kept for each unit and made available to the inspector; missing records are a common cause of failed inspections.

Tag-out/lock-out is required before any work in the hoistway or machine room; the mainline disconnect must be locked open and the key controlled by the mechanic.

Michigan elevator work is regulated by the Elevator Safety Board within the Department of Licensing and Regulatory Affairs (LARA); the board adopts ASME A17.1 and A17.3 by reference.

Elevator mechanic and elevator contractor licenses are issued by LARA; work must be performed by or under the direct supervision of a licensed elevator mechanic.

Continuing education is required to renew a mechanic license; the board sets the hours and approved course categories.

Permits are required before installing or altering an elevator; the contractor submits plans and the state inspects before the unit is placed in service.

Periodic inspections in Michigan are performed at intervals set by rule; the owner is responsible for arranging inspection and paying fees.

A certificate of operation must be posted in the elevator car or machine room and renewed annually after inspection.

Unlicensed elevator work is a violation subject to civil penalties and may result in the contractor's license suspension or revocation.

Appeals of board or department decisions go through the Michigan Administrative Hearing System; a request must be filed within the time stated in the department's notice.

OSHA fall protection for general industry is triggered at 4 ft; in construction, at 6 ft. Elevator hoistway work uses fall protection at the pit and at the car top.

A full-body harness with lanyard and a rated anchor point is required for hoistway work; the anchor must support 5,000 lb per worker or be designed by a qualified person.

Rigging: the working load limit of a sling is its vertical rating reduced by the sling angle; at 30 degrees from horizontal, capacity drops to 50% of vertical.

Never exceed the rated capacity of a shackle, hook, or chain; hooks must have a functioning safety latch and be inspected before each lift.

Hoisting a car or counterweight requires a rated beam or hoist point and a load test before personnel work under it; never use the elevator machine as a rigging point.

Lockout/tagout (29 CFR 1910.147) applies to elevator maintenance: isolate all energy sources, verify zero energy, and apply personal locks.

Confined-space entry rules apply to pits with limited access; test for oxygen, combustible gas, and hydrogen sulfide before entry where applicable.

Housekeeping: keep the pit and machine room clear of oil, tools, and debris; oil on the pit floor is a slip hazard and a fire hazard.

A17.1/B44 is the design, construction, installation, and alteration code; A17.2 covers inspection, A17.3 covers existing installations, and A17.5 covers electrical equipment.

Minimum rated load for passenger elevators is based on car floor area: 50 lb per square foot of net floor area is the lower bound used with the code's area-load table.

Clear inside car height must be at least 7 ft (2.13 m); car doors must be at least 6 ft 8 in (2.03 m) high and provide an unobstructed clear opening.

Required car lighting: at least 2 ft-candles (21.5 lux) at the car floor with doors closed, and emergency lighting of at least 5 ft-candles for 4 hours at the car threshold.

Escalator: maximum rise per unit is 60 ft (18.3 m); nominal speed may not exceed 125 ft/min (0.63 m/s) where the rise exceeds 20 ft, and 100 ft/min where rise is 20 ft or less.

Escalator rated load is computed as 2 persons per 16 in (400 mm) of nominal width per step band segment; the code assumes 50% occupancy for capacity-based calculations.

Escalator clearance: minimum 7 ft (2.13 m) vertical clearance above the step band to any obstruction, and 2 ft 4 in (711 mm) between handrail centerlines minimum.

Machine-room and control-space access doors must be self-closing and self-locking, open outward, and be at least 30 in (762 mm) wide by 6 ft 8 in (2.03 m) high.

Ohm's law: E = I x R; power in a DC or resistive circuit: P = E x I = I^2 R = E^2 / R.

Three-phase power: P (watts) = 1.732 x E_line x I_line x power factor; synchronous speed N = 120f / P where P is pole count.

Motor slip: percent slip = (N_sync - N_measured) / N_sync x 100; typical NEMA Design B induction motors run 2-4% slip at rated load.

Across-the-line starting draws roughly 6x nameplate full-load current; wye-delta and reduced-voltage starters lower inrush at the cost of torque.

A dynamic braking resistor converts motor kinetic energy to heat during deceleration; the resistor's duty rating, not its ohmic value alone, sets its thermal limit.

NEMA contactor sizing is by horsepower rating and utilization category (AC-3 for squirrel-cage motor starting), not just by amp rating.

A ground-fault circuit must trip at 5 mA +/- 1 mA for personnel protection; equipment GFCI in elevator circuits is typically set at 30 mA or higher per code.

Variable-frequency drives require shielded motor cable with the shield grounded at the drive end; long cable runs cause reflected-wave overvoltage at the motor terminals.

Traction ratio = total load on the sheave divided by the lesser rope tension; 1:1 roping has a ratio of 1, 2:1 has 2, and higher ratios reduce rope load but double rope travel.

Suspension rope safety factor: at least 12 for traction elevators with rated speed above 50 ft/min, and at least 16 for drum-type machines per A17.1.

Minimum number of suspension ropes is 3 for traction elevators; each rope must be independently terminated and equalized.

Rope construction for elevators is typically 6x19 or 8x19 seale independent wire rope core (IWRC); fiber-core ropes are not permitted for traction suspension.

Sheave-to-rope diameter ratio must be at least 40:1 for traction machines; smaller ratios accelerate fatigue and require more frequent inspection.

Rope wear rejection: replace when diameter reduction exceeds the code limit (roughly 3% below nominal for 6-8 strand ropes) or when broken wires in one lay exceed the A17.1 table.

Counterweight equals car weight plus approximately 40-50% of rated load, balancing the system so the machine sees near-equal tension up and down.

Guide rail alignment tolerance is typically 1/8 in (3 mm) over 5 ft; misalignment causes roller or gib wear and car sway.

Governor tripping speed is set between 115% and 140% of rated speed for car governors; the tripping speed must not exceed the value in the A17.1 table for the rated speed.

The safety (car or counterweight) must stop the car within the code's deceleration limit; the governor tripping speed and safety setting combine to produce this.

Instantaneous safeties are permitted only below the code's speed threshold (typically 200 ft/min for cars); above that, type A or type B progressive safeties are required.

The governor rope must be at least 1/4 in (6.4 mm) diameter and must be tensioned so the governor operates before the car reaches the pit buffers.

Buffers: oil buffers are required for rated speeds above 200 ft/min; spring buffers are permitted below that. Buffer stroke must match the code table for rated speed.

Brake torque must hold 125% of rated load; the brake is set by spring and released by magnet or hydraulic pressure, so loss of power applies the brake.

The brake must be a friction type with a self-engaging design; a brake that depends on electrical or hydraulic power to set is not permitted.

Final limit switches must be independent of the normal limit switches and must open the power circuit before the car or counterweight reaches the buffer.

Hydraulic elevators are limited to a maximum travel of about 60 ft (18.3 m) for in-ground cylinders and 50 ft (15.2 m) for holeless telescoping cylinders.

Rated speed of a hydraulic elevator is set by pump displacement and plunger area: v = Q / A, so doubling plunger area halves speed at the same flow.

The relief valve must be set to open at no more than 150% of the full-load pressure and must be tested with the car at rest and loaded.

The check valve holds the car when the pump stops; the lowering valve controls descent. Both must be tested for leakage and response time.

The pressure switch and rupture valve protect against line failure; the rupture valve must close when flow exceeds the design limit, stopping the car.

Hydraulic fluid temperature affects viscosity and speed; typical operating range is 60-140 F, and low temperature raises pressure and slows descent.

The cylinder must have a means to detect and remove air; trapped air causes spongy ride and can allow the car to drop when the pump stops.

The pit must have a drain or sump and the cylinder must be protected against corrosion; a failed cylinder casing leaks oil into the pit and is a code violation.

Periodic inspection intervals are set by the authority having jurisdiction; A17.2 inspection procedures cover car, machine room, pit, and hoistway, in that order.

Annual tests include: safety device test with rated load, governor tripping speed, buffer test, brake test, and relief valve test on hydraulic units.

Five-year tests include: safety device test at 125% of rated load and a full-load test of the machine and brake.

The governor tripping speed is measured with a tachometer at the governor or by the rope speed; record the measured speed and compare to the A17.1 table.

The safety test is performed by tripping the governor and observing the car stop; measure the stopping distance and check for even engagement of both safety blocks.

Escalator inspection: check step-to-skirt clearance (not more than 3/16 in per side), comb teeth engagement, handrail speed, and the stop switch operation.

Maintenance records must be kept for each unit and made available to the inspector; missing records are a common cause of failed inspections.

Tag-out/lock-out is required before any work in the hoistway or machine room; the mainline disconnect must be locked open and the key controlled by the mechanic.

Michigan elevator work is regulated by the Elevator Safety Board within the Department of Licensing and Regulatory Affairs (LARA); the board adopts ASME A17.1 and A17.3 by reference.

Elevator mechanic and elevator contractor licenses are issued by LARA; work must be performed by or under the direct supervision of a licensed elevator mechanic.

Continuing education is required to renew a mechanic license; the board sets the hours and approved course categories.

Permits are required before installing or altering an elevator; the contractor submits plans and the state inspects before the unit is placed in service.

Periodic inspections in Michigan are performed at intervals set by rule; the owner is responsible for arranging inspection and paying fees.

A certificate of operation must be posted in the elevator car or machine room and renewed annually after inspection.

Unlicensed elevator work is a violation subject to civil penalties and may result in the contractor's license suspension or revocation.

Appeals of board or department decisions go through the Michigan Administrative Hearing System; a request must be filed within the time stated in the department's notice.

OSHA fall protection for general industry is triggered at 4 ft; in construction, at 6 ft. Elevator hoistway work uses fall protection at the pit and at the car top.

A full-body harness with lanyard and a rated anchor point is required for hoistway work; the anchor must support 5,000 lb per worker or be designed by a qualified person.

Rigging: the working load limit of a sling is its vertical rating reduced by the sling angle; at 30 degrees from horizontal, capacity drops to 50% of vertical.

Never exceed the rated capacity of a shackle, hook, or chain; hooks must have a functioning safety latch and be inspected before each lift.

Hoisting a car or counterweight requires a rated beam or hoist point and a load test before personnel work under it; never use the elevator machine as a rigging point.

Lockout/tagout (29 CFR 1910.147) applies to elevator maintenance: isolate all energy sources, verify zero energy, and apply personal locks.

Confined-space entry rules apply to pits with limited access; test for oxygen, combustible gas, and hydrogen sulfide before entry where applicable.

Housekeeping: keep the pit and machine room clear of oil, tools, and debris; oil on the pit floor is a slip hazard and a fire hazard.

A17.1/B44 is the design, construction, installation, and alteration code; A17.2 covers inspection, A17.3 covers existing installations, and A17.5 covers electrical equipment.

Minimum rated load for passenger elevators is based on car floor area: 50 lb per square foot of net floor area is the lower bound used with the code's area-load table.

Clear inside car height must be at least 7 ft (2.13 m); car doors must be at least 6 ft 8 in (2.03 m) high and provide an unobstructed clear opening.

Required car lighting: at least 2 ft-candles (21.5 lux) at the car floor with doors closed, and emergency lighting of at least 5 ft-candles for 4 hours at the car threshold.

Escalator: maximum rise per unit is 60 ft (18.3 m); nominal speed may not exceed 125 ft/min (0.63 m/s) where the rise exceeds 20 ft, and 100 ft/min where rise is 20 ft or less.

Escalator rated load is computed as 2 persons per 16 in (400 mm) of nominal width per step band segment; the code assumes 50% occupancy for capacity-based calculations.

Escalator clearance: minimum 7 ft (2.13 m) vertical clearance above the step band to any obstruction, and 2 ft 4 in (711 mm) between handrail centerlines minimum.

Machine-room and control-space access doors must be self-closing and self-locking, open outward, and be at least 30 in (762 mm) wide by 6 ft 8 in (2.03 m) high.

Ohm's law: E = I x R; power in a DC or resistive circuit: P = E x I = I^2 R = E^2 / R.

Three-phase power: P (watts) = 1.732 x E_line x I_line x power factor; synchronous speed N = 120f / P where P is pole count.

Motor slip: percent slip = (N_sync - N_measured) / N_sync x 100; typical NEMA Design B induction motors run 2-4% slip at rated load.

Across-the-line starting draws roughly 6x nameplate full-load current; wye-delta and reduced-voltage starters lower inrush at the cost of torque.

A dynamic braking resistor converts motor kinetic energy to heat during deceleration; the resistor's duty rating, not its ohmic value alone, sets its thermal limit.

NEMA contactor sizing is by horsepower rating and utilization category (AC-3 for squirrel-cage motor starting), not just by amp rating.

A ground-fault circuit must trip at 5 mA +/- 1 mA for personnel protection; equipment GFCI in elevator circuits is typically set at 30 mA or higher per code.

Variable-frequency drives require shielded motor cable with the shield grounded at the drive end; long cable runs cause reflected-wave overvoltage at the motor terminals.

Traction ratio = total load on the sheave divided by the lesser rope tension; 1:1 roping has a ratio of 1, 2:1 has 2, and higher ratios reduce rope load but double rope travel.

Suspension rope safety factor: at least 12 for traction elevators with rated speed above 50 ft/min, and at least 16 for drum-type machines per A17.1.

Minimum number of suspension ropes is 3 for traction elevators; each rope must be independently terminated and equalized.

Rope construction for elevators is typically 6x19 or 8x19 seale independent wire rope core (IWRC); fiber-core ropes are not permitted for traction suspension.

Sheave-to-rope diameter ratio must be at least 40:1 for traction machines; smaller ratios accelerate fatigue and require more frequent inspection.

Rope wear rejection: replace when diameter reduction exceeds the code limit (roughly 3% below nominal for 6-8 strand ropes) or when broken wires in one lay exceed the A17.1 table.

Counterweight equals car weight plus approximately 40-50% of rated load, balancing the system so the machine sees near-equal tension up and down.

Guide rail alignment tolerance is typically 1/8 in (3 mm) over 5 ft; misalignment causes roller or gib wear and car sway.

Governor tripping speed is set between 115% and 140% of rated speed for car governors; the tripping speed must not exceed the value in the A17.1 table for the rated speed.

The safety (car or counterweight) must stop the car within the code's deceleration limit; the governor tripping speed and safety setting combine to produce this.

Instantaneous safeties are permitted only below the code's speed threshold (typically 200 ft/min for cars); above that, type A or type B progressive safeties are required.

The governor rope must be at least 1/4 in (6.4 mm) diameter and must be tensioned so the governor operates before the car reaches the pit buffers.

Buffers: oil buffers are required for rated speeds above 200 ft/min; spring buffers are permitted below that. Buffer stroke must match the code table for rated speed.

Brake torque must hold 125% of rated load; the brake is set by spring and released by magnet or hydraulic pressure, so loss of power applies the brake.

The brake must be a friction type with a self-engaging design; a brake that depends on electrical or hydraulic power to set is not permitted.

Final limit switches must be independent of the normal limit switches and must open the power circuit before the car or counterweight reaches the buffer.

Hydraulic elevators are limited to a maximum travel of about 60 ft (18.3 m) for in-ground cylinders and 50 ft (15.2 m) for holeless telescoping cylinders.

Rated speed of a hydraulic elevator is set by pump displacement and plunger area: v = Q / A, so doubling plunger area halves speed at the same flow.

The relief valve must be set to open at no more than 150% of the full-load pressure and must be tested with the car at rest and loaded.

The check valve holds the car when the pump stops; the lowering valve controls descent. Both must be tested for leakage and response time.

The pressure switch and rupture valve protect against line failure; the rupture valve must close when flow exceeds the design limit, stopping the car.

Hydraulic fluid temperature affects viscosity and speed; typical operating range is 60-140 F, and low temperature raises pressure and slows descent.

The cylinder must have a means to detect and remove air; trapped air causes spongy ride and can allow the car to drop when the pump stops.

The pit must have a drain or sump and the cylinder must be protected against corrosion; a failed cylinder casing leaks oil into the pit and is a code violation.

Periodic inspection intervals are set by the authority having jurisdiction; A17.2 inspection procedures cover car, machine room, pit, and hoistway, in that order.

Annual tests include: safety device test with rated load, governor tripping speed, buffer test, brake test, and relief valve test on hydraulic units.

Five-year tests include: safety device test at 125% of rated load and a full-load test of the machine and brake.

The governor tripping speed is measured with a tachometer at the governor or by the rope speed; record the measured speed and compare to the A17.1 table.

The safety test is performed by tripping the governor and observing the car stop; measure the stopping distance and check for even engagement of both safety blocks.

Escalator inspection: check step-to-skirt clearance (not more than 3/16 in per side), comb teeth engagement, handrail speed, and the stop switch operation.

Maintenance records must be kept for each unit and made available to the inspector; missing records are a common cause of failed inspections.

Tag-out/lock-out is required before any work in the hoistway or machine room; the mainline disconnect must be locked open and the key controlled by the mechanic.

Michigan elevator work is regulated by the Elevator Safety Board within the Department of Licensing and Regulatory Affairs (LARA); the board adopts ASME A17.1 and A17.3 by reference.

Elevator mechanic and elevator contractor licenses are issued by LARA; work must be performed by or under the direct supervision of a licensed elevator mechanic.

Continuing education is required to renew a mechanic license; the board sets the hours and approved course categories.

Permits are required before installing or altering an elevator; the contractor submits plans and the state inspects before the unit is placed in service.

Periodic inspections in Michigan are performed at intervals set by rule; the owner is responsible for arranging inspection and paying fees.

A certificate of operation must be posted in the elevator car or machine room and renewed annually after inspection.

Unlicensed elevator work is a violation subject to civil penalties and may result in the contractor's license suspension or revocation.

Appeals of board or department decisions go through the Michigan Administrative Hearing System; a request must be filed within the time stated in the department's notice.

OSHA fall protection for general industry is triggered at 4 ft; in construction, at 6 ft. Elevator hoistway work uses fall protection at the pit and at the car top.

A full-body harness with lanyard and a rated anchor point is required for hoistway work; the anchor must support 5,000 lb per worker or be designed by a qualified person.

Rigging: the working load limit of a sling is its vertical rating reduced by the sling angle; at 30 degrees from horizontal, capacity drops to 50% of vertical.

Never exceed the rated capacity of a shackle, hook, or chain; hooks must have a functioning safety latch and be inspected before each lift.

Hoisting a car or counterweight requires a rated beam or hoist point and a load test before personnel work under it; never use the elevator machine as a rigging point.

Lockout/tagout (29 CFR 1910.147) applies to elevator maintenance: isolate all energy sources, verify zero energy, and apply personal locks.

Confined-space entry rules apply to pits with limited access; test for oxygen, combustible gas, and hydrogen sulfide before entry where applicable.

Housekeeping: keep the pit and machine room clear of oil, tools, and debris; oil on the pit floor is a slip hazard and a fire hazard.

A17.1/B44 is the design, construction, installation, and alteration code; A17.2 covers inspection, A17.3 covers existing installations, and A17.5 covers electrical equipment.

Minimum rated load for passenger elevators is based on car floor area: 50 lb per square foot of net floor area is the lower bound used with the code's area-load table.

Clear inside car height must be at least 7 ft (2.13 m); car doors must be at least 6 ft 8 in (2.03 m) high and provide an unobstructed clear opening.

Required car lighting: at least 2 ft-candles (21.5 lux) at the car floor with doors closed, and emergency lighting of at least 5 ft-candles for 4 hours at the car threshold.

Escalator: maximum rise per unit is 60 ft (18.3 m); nominal speed may not exceed 125 ft/min (0.63 m/s) where the rise exceeds 20 ft, and 100 ft/min where rise is 20 ft or less.

Escalator rated load is computed as 2 persons per 16 in (400 mm) of nominal width per step band segment; the code assumes 50% occupancy for capacity-based calculations.

Escalator clearance: minimum 7 ft (2.13 m) vertical clearance above the step band to any obstruction, and 2 ft 4 in (711 mm) between handrail centerlines minimum.

Machine-room and control-space access doors must be self-closing and self-locking, open outward, and be at least 30 in (762 mm) wide by 6 ft 8 in (2.03 m) high.

Ohm's law: E = I x R; power in a DC or resistive circuit: P = E x I = I^2 R = E^2 / R.

Three-phase power: P (watts) = 1.732 x E_line x I_line x power factor; synchronous speed N = 120f / P where P is pole count.

Motor slip: percent slip = (N_sync - N_measured) / N_sync x 100; typical NEMA Design B induction motors run 2-4% slip at rated load.

Across-the-line starting draws roughly 6x nameplate full-load current; wye-delta and reduced-voltage starters lower inrush at the cost of torque.

A dynamic braking resistor converts motor kinetic energy to heat during deceleration; the resistor's duty rating, not its ohmic value alone, sets its thermal limit.

NEMA contactor sizing is by horsepower rating and utilization category (AC-3 for squirrel-cage motor starting), not just by amp rating.

A ground-fault circuit must trip at 5 mA +/- 1 mA for personnel protection; equipment GFCI in elevator circuits is typically set at 30 mA or higher per code.

Variable-frequency drives require shielded motor cable with the shield grounded at the drive end; long cable runs cause reflected-wave overvoltage at the motor terminals.

Traction ratio = total load on the sheave divided by the lesser rope tension; 1:1 roping has a ratio of 1, 2:1 has 2, and higher ratios reduce rope load but double rope travel.

Suspension rope safety factor: at least 12 for traction elevators with rated speed above 50 ft/min, and at least 16 for drum-type machines per A17.1.

Minimum number of suspension ropes is 3 for traction elevators; each rope must be independently terminated and equalized.

Rope construction for elevators is typically 6x19 or 8x19 seale independent wire rope core (IWRC); fiber-core ropes are not permitted for traction suspension.

Sheave-to-rope diameter ratio must be at least 40:1 for traction machines; smaller ratios accelerate fatigue and require more frequent inspection.

Rope wear rejection: replace when diameter reduction exceeds the code limit (roughly 3% below nominal for 6-8 strand ropes) or when broken wires in one lay exceed the A17.1 table.

Counterweight equals car weight plus approximately 40-50% of rated load, balancing the system so the machine sees near-equal tension up and down.

Guide rail alignment tolerance is typically 1/8 in (3 mm) over 5 ft; misalignment causes roller or gib wear and car sway.

Governor tripping speed is set between 115% and 140% of rated speed for car governors; the tripping speed must not exceed the value in the A17.1 table for the rated speed.

The safety (car or counterweight) must stop the car within the code's deceleration limit; the governor tripping speed and safety setting combine to produce this.

Instantaneous safeties are permitted only below the code's speed threshold (typically 200 ft/min for cars); above that, type A or type B progressive safeties are required.

The governor rope must be at least 1/4 in (6.4 mm) diameter and must be tensioned so the governor operates before the car reaches the pit buffers.

Buffers: oil buffers are required for rated speeds above 200 ft/min; spring buffers are permitted below that. Buffer stroke must match the code table for rated speed.

Brake torque must hold 125% of rated load; the brake is set by spring and released by magnet or hydraulic pressure, so loss of power applies the brake.

The brake must be a friction type with a self-engaging design; a brake that depends on electrical or hydraulic power to set is not permitted.

Final limit switches must be independent of the normal limit switches and must open the power circuit before the car or counterweight reaches the buffer.

Hydraulic elevators are limited to a maximum travel of about 60 ft (18.3 m) for in-ground cylinders and 50 ft (15.2 m) for holeless telescoping cylinders.

Rated speed of a hydraulic elevator is set by pump displacement and plunger area: v = Q / A, so doubling plunger area halves speed at the same flow.

The relief valve must be set to open at no more than 150% of the full-load pressure and must be tested with the car at rest and loaded.

The check valve holds the car when the pump stops; the lowering valve controls descent. Both must be tested for leakage and response time.

The pressure switch and rupture valve protect against line failure; the rupture valve must close when flow exceeds the design limit, stopping the car.

Hydraulic fluid temperature affects viscosity and speed; typical operating range is 60-140 F, and low temperature raises pressure and slows descent.

The cylinder must have a means to detect and remove air; trapped air causes spongy ride and can allow the car to drop when the pump stops.

The pit must have a drain or sump and the cylinder must be protected against corrosion; a failed cylinder casing leaks oil into the pit and is a code violation.

Periodic inspection intervals are set by the authority having jurisdiction; A17.2 inspection procedures cover car, machine room, pit, and hoistway, in that order.

Annual tests include: safety device test with rated load, governor tripping speed, buffer test, brake test, and relief valve test on hydraulic units.

Five-year tests include: safety device test at 125% of rated load and a full-load test of the machine and brake.

The governor tripping speed is measured with a tachometer at the governor or by the rope speed; record the measured speed and compare to the A17.1 table.

The safety test is performed by tripping the governor and observing the car stop; measure the stopping distance and check for even engagement of both safety blocks.

Escalator inspection: check step-to-skirt clearance (not more than 3/16 in per side), comb teeth engagement, handrail speed, and the stop switch operation.

Maintenance records must be kept for each unit and made available to the inspector; missing records are a common cause of failed inspections.

Tag-out/lock-out is required before any work in the hoistway or machine room; the mainline disconnect must be locked open and the key controlled by the mechanic.

Michigan elevator work is regulated by the Elevator Safety Board within the Department of Licensing and Regulatory Affairs (LARA); the board adopts ASME A17.1 and A17.3 by reference.

Elevator mechanic and elevator contractor licenses are issued by LARA; work must be performed by or under the direct supervision of a licensed elevator mechanic.

Continuing education is required to renew a mechanic license; the board sets the hours and approved course categories.

Permits are required before installing or altering an elevator; the contractor submits plans and the state inspects before the unit is placed in service.

Periodic inspections in Michigan are performed at intervals set by rule; the owner is responsible for arranging inspection and paying fees.

A certificate of operation must be posted in the elevator car or machine room and renewed annually after inspection.

Unlicensed elevator work is a violation subject to civil penalties and may result in the contractor's license suspension or revocation.

Appeals of board or department decisions go through the Michigan Administrative Hearing System; a request must be filed within the time stated in the department's notice.

OSHA fall protection for general industry is triggered at 4 ft; in construction, at 6 ft. Elevator hoistway work uses fall protection at the pit and at the car top.

A full-body harness with lanyard and a rated anchor point is required for hoistway work; the anchor must support 5,000 lb per worker or be designed by a qualified person.

Rigging: the working load limit of a sling is its vertical rating reduced by the sling angle; at 30 degrees from horizontal, capacity drops to 50% of vertical.

Never exceed the rated capacity of a shackle, hook, or chain; hooks must have a functioning safety latch and be inspected before each lift.

Hoisting a car or counterweight requires a rated beam or hoist point and a load test before personnel work under it; never use the elevator machine as a rigging point.

Lockout/tagout (29 CFR 1910.147) applies to elevator maintenance: isolate all energy sources, verify zero energy, and apply personal locks.

Confined-space entry rules apply to pits with limited access; test for oxygen, combustible gas, and hydrogen sulfide before entry where applicable.

Housekeeping: keep the pit and machine room clear of oil, tools, and debris; oil on the pit floor is a slip hazard and a fire hazard.