CML CML Access Control & Electromechanical Systems 1 — Questions and Answers
Question 1: What is the primary difference between a fail-safe and a fail-secure electrified lock?
- Fail-safe locks require a key to open; fail-secure locks do not
- Fail-safe locks are unlocked when power is lost; fail-secure locks remain locked when power is lost (Correct answer)
- Fail-safe locks are used outdoors; fail-secure locks are used indoors
- Fail-safe locks are cheaper than fail-secure locks
Correct answer: Fail-safe locks are unlocked when power is lost; fail-secure locks remain locked when power is lost
Fail-safe locks release and allow egress when power is cut, while fail-secure locks remain locked during a power outage, maintaining security.
Question 2: An electric strike differs from an electromagnetic lock in that an electric strike:
- Requires continuous power to stay locked
- Replaces the strike plate and releases mechanically, allowing the door hardware to remain passive (Correct answer)
- Cannot be used on exterior doors
- Only works with proximity card readers
Correct answer: Replaces the strike plate and releases mechanically, allowing the door hardware to remain passive
An electric strike replaces the standard strike plate and releases to allow the latch or bolt to pass, whereas an electromagnetic lock holds the door via magnetic attraction requiring constant power.
Question 3: What is the standard voltage used for most low-voltage access control locking devices in the US?
- 120V AC
- 24V DC or 12V DC (Correct answer)
- 48V DC
- 9V DC
Correct answer: 24V DC or 12V DC
Most access control locking hardware operates on 12V DC or 24V DC low-voltage power to comply with safety codes and allow use with standard access control power supplies.
Question 4: Which wiring configuration allows monitoring of a door contact's open, closed, and tampered (wire cut) states?
- Normally open (NO) wiring
- Normally closed (NC) wiring
- Supervised circuit with end-of-line resistors (Correct answer)
- Double-pole double-throw (DPDT) wiring
Correct answer: Supervised circuit with end-of-line resistors
Supervised circuits with end-of-line (EOL) resistors allow the access control system to distinguish between normal closed, normal open, and tampered/shorted states.
Question 5: A mortise-style electrified lockset is typically preferred over a cylindrical electrified lockset for high-traffic commercial doors because:
- Mortise locks are less expensive
- Mortise locks have a heavier-duty body and integrate the latch, deadbolt, and electrical components more robustly (Correct answer)
- Mortise locks do not require a door prep
- Mortise locks can be installed without cutting into the door edge
Correct answer: Mortise locks have a heavier-duty body and integrate the latch, deadbolt, and electrical components more robustly
Mortise lock bodies are thicker and more mechanically robust, making them better suited for high-traffic commercial applications where durability is critical.
Question 6: When installing an electromagnetic lock on a door that must comply with ADA and fire code, the CML must ensure:
- The magnet exceeds 1,500 lbs. holding force
- A request-to-exit (REX) motion sensor or push-plate is installed so the door can be opened without a credential (Correct answer)
- The magnet is surface-mounted on the pull side only
- The power supply is connected to the main electrical panel, not a dedicated circuit
Correct answer: A request-to-exit (REX) motion sensor or push-plate is installed so the door can be opened without a credential
ADA and fire codes require that electrified doors have a means of egress that does not require a credential, typically a REX sensor or a push-to-exit button.
CML CML Access Control & Electromechanical Systems 1
What is the primary difference between a fail-safe and a fail-secure electrified lock?