ElectroLock

Frequently Asked Questions

What is a door restrictor?

A door restrictor is a device, attached to the outside of an elevator car, that secures the car doors when the car is in transit between safe landing zones.

What is a safe landing zone?

Also referred to as the unlocking zone, the minimum safe landing zone is a vertical span of 6 inches that extends 3 inches above and 3 inches below an elevator landing. It is permissible for this span to extend up to 18 inches above or below the landing.

Why are door restrictors necessary?

Elevator safety codes mandate the use of door restrictors as a safety measure. The primary rule is ASME A17.1, 111.5, which specifies the requirement for door restrictors:

(a) When a car is outside the unlocking zone, the hoistway doors or car doors shall be so arranged that they cannot be opened more than 4 in. (102 mm) from inside the car.

(b) When the car doors are so arranged that they cannot be opened when the car is outside the unlockiing zone, the car doors shall be openable from outside the car without the use of a special tool.

(c) The doors shall be unlocked when the car within 3 in. (76 mm) above or below the landing and shall be permitted to be unlocked up to 18 in. (457 mm) above or below the landing.

For elevators installed under the 1980 edition of ASME A17.1 and later, door restrictor guidelines are provided in ASME A17.1 1998b Rule 111.5/111.12 or ASME A17.1 2000 Item 2.12.5.

The A17.1 Handbook Safety Code for Elevators and Escalators, 2000 Edition, Section 2.12.5, explains the reasoning behind the use of door restrictors in this way:

When a passenger elevator is outside the unlocking zone it is unsafe for a passenger to try to exit through the elevator entrance unassisted . . . In fact, there have been many reports of fatalities due to this condition. A person inside the car should not be able to accomplish their own emergency evacuation through a hoistway door when the car is located outside of the unlocking zone. This requirement may be met by restricting the opening of the car door or the hoistway door.

Industry and safety experts have reached a broad concensus that during emergencies and power-loss events, the safest place for elevator passengers is inside the car until they can be rescued by professional responders.

Are any elevators exempt from the requirement for door restrictors?

The requirement for elevator door restrictors varies by state. The general trend is for all elevators to be equipped with door restrictors. Most variances apply to to the length of time available for an operator to bring a given elevator into compliance with the code. If you are unsure of the requirement in your state, consult with your elevator’s certifying authority.

Why is Electrodyn introducing a new type of door restrictor?

To date, manufacturers have explored two approaches to door restrictor design—mechanical and electromagnetic. The first type, mechanical door restrictors, are problematic because they tend to be noisy and are difficult to align and repair. The second type, electromagnetic door restrictors, use photoelectric sensors instead of metal-to-metal contact. However, calibrating the electric eyes and target strips used by these devices is time-consuming, and the functionality of these systems is degraded in the presence of dust, smoke, grime, and ambient light. Both types of door restrictors are subject to failure in an unsafe position.

ElectroLock™ was designed to address all known problems with mechanical and electromagnetic door restrictors, even to the point that should the system fail for any reason, it will fail in the safe position.

Is ElectroLock an electromagnetic device?

ElectroLock uses RFID (radio frequency identification) technology instead of photoelectric beams and targets. However, like other electromagnetic door restrictors, ElectroLock uses electricity to power a locking plunger to secure elevator car doors.

Is ElectroLock code compliant?

Yes. Note that according to ASME Inquiry 00–30, “an electrical device with battery back-up” is not code compliant. But ElectroLock uses a bi-stable solenoid that retains its state through the use of permanent magnets. There are no batteries required. In the event of power loss, ElectroLock holds its current position until receiving additional input. That’s why ElectroLock is the only code-compliant electric door restrictor.

Does ElectroLock require regular maintenance?

Once installed, ElectroLock should require no maintenance whatsoever. The magnalatch locking solenoid is the system’s only moving part. The bolt is permanently lubricated and the solenoid is powered with micropulses of electricity, not continuous current as seen in other systems. Timing logic in the controller prevents magnalatch from cycling until arriving at destination landings, further extending system longevity. ElectroLock is engineered to be more durable and reliable than any other door restrictor available.

What happens if the door operator activates while ElectroLock is engaged?

We strongly recommend an arrangement called “doorsaver,” whereby ElectroLock is wired into an elevator door operator’s door-open limit circuit, as this allows the system to interact intelligently with the door operator and prevent door motor burnout should the motor misfunction. That is, doorsaver will not allow the door operator to open or close car doors if the magnalatch locking plunger is in position.

How much does ElectroLock cost?

ElectroLock is aggressively priced to be less than most other door restrictors and a standard installation will be in the hundreds, not thousands of dollars per car. Installation is fast because the system uses a combination of LED signaling and an audible tone generated by the controller to confirm the placement of electrosensor landing targets. The combination of low component cost, quick installation time, eliminated maintenance and door operator protection presents a tremendous value. Request a quote and let us show you how affordable ElectroLock is.

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