Jumpered Door Interlock Found During Maintenance
During a routine maintenance visit at an eight-story, 2,500 lb, 200 fpm traction elevator, the mechanic finds a short jumper wire across the contacts of a hoistway door interlock at floor 5. The car will run normally with the floor-5 hoistway door unlocked and open about 2 inches. The door roller is worn and the lock engagement is shallow. The building has a new tenant moving in, and the owner says the elevator passed inspection six months ago and asks the mechanic to just adjust the roller and sign off because the moving trucks arrive Friday. The mechanic also notices fresh scrape marks on the floor-5 door track and a missing screw on the interlock cover.
1. What is the immediate action, and why is adjusting the roller insufficient?
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The immediate action is to place the elevator out of service and secure it so it cannot be operated from any landing or from the car. Lock out and tag out the main power, remove the jumper, and do not return the car to service until the interlock circuit is proven intact. Adjusting the roller is insufficient because the jumper is an intentional bypass of a safety device. A proper roller adjustment might make the door lock engage, but it would not explain who installed the jumper, how long it has been there, or whether other floors have the same condition. The worn roller and shallow engagement are maintenance defects; the jumper is a safety violation. The owner's schedule does not change the hazard. The mechanic should also treat the fresh scrape marks and missing cover screw as evidence that the door and lock have been disturbed and require a broader inspection.
2. How would you determine the extent of the bypass and what tests are required?
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Inspect every hoistway door interlock and gate switch on all floors, not just floor 5. Look for jumpers, taped contacts, modified wiring, missing covers, and nonstandard terminations. Trace the lock circuit and compare it with the wiring diagram. Operate each door by hand and verify that the car cannot run unless every hoistway door and gate is locked and the car door is closed as required. Test the door lock monitoring function if the elevator is equipped with it, and verify that a single unlocked door stops the car. Check the car door interlock and the gate switch. Review maintenance records and ask who last worked on the door. Because a bypass can defeat the safety circuit, the tests should be witnessed and documented, and the AHJ or inspection agency should be notified if local rules require reporting of the hazard.
3. What documentation and communication should accompany return to service?
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Document the exact condition found, including the jumper location, the open-door running condition, the worn roller, the shallow lock engagement, and the missing cover screw. Photograph the findings before removing the jumper. Record the tests performed on every floor, the door lock monitoring result, and any parts replaced. Notify the owner in writing that the elevator was removed from service because a safety device was bypassed, not because of a routine adjustment. If an inspection agency or AHJ requires notification of the hazard, make that notification before return to service. Return the car only after all interlocks are verified, the door roller and lock engagement are corrected, and a qualified person has completed the required inspection. The mechanic should not sign an inspection document for work he or she did not verify. A clear written record protects the mechanic and prevents the owner from treating a safety violation as a scheduling inconvenience.