CML Cheat Sheet 2026

The 30 highest-yield CML facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. An alarm panel's backup battery is required to power the system for how long in the absence of AC power under UL 681 standards? → 24 hours
2. Which type of lock cylinder is most commonly found in a standard residential knob or lever lockset? → Cylindrical (key-in-knob) cylinder
3. What does 'keyed alike' (KA) mean when specified on a lock order? → All locks in the order are operated by the same key
4. Which wiring configuration allows monitoring of a door contact's open, closed, and tampered (wire cut) states? → Supervised circuit with end-of-line resistors
5. What role does calibration play in maintaining technical accuracy for Certified Master Locksmith professionals? → It ensures instruments produce accurate, consistent results over time
6. What is a master key system? → Key that opens multiple locks
7. Why is regular maintenance important for security systems? → Ensure reliable function and detection
8. What is the importance of honesty in business dealings? → Build trust and relationships
9. When drilling a safe, which area is typically targeted to bypass the combination lock? → The drill point above the dial to access the lock lever pack
10. What is the PROPER procedure for decommissioning outdated equipment in Certified Master Locksmith? → Follow established protocols for safe decommissioning, data clearing, and proper disposal
11. A locksmith business operating in multiple states must: → Obtain all required licenses and permits in each state where work is performed
12. When servicing a Sergeant & Greenleaf (S&G) three-wheel combination lock, what is the standard method to set a new combination? → Use the change key inserted in the back of the lock to set each wheel's gate position
13. Why is professional ethics important in locksmithing? → Build trust and reputation
14. What is the role of professional associations for locksmiths? → Offer education and standards
15. Which factor MOST significantly affects the quality of technical outcomes in CML practice? → The practitioner's training, preparation, and attention to detail
16. A CML employee reports witnessing a colleague accepting payment to make unauthorized key copies. The CML owner should FIRST: → Conduct a confidential internal investigation and document findings
17. What is the first step a CML technician should take when a customer reports a safe with an unknown combination? → Verify ownership documentation before attempting any entry
18. Under NEC Article 760, low-voltage fire alarm wiring must be kept separate from which of the following? → 120V or higher power wiring
19. Which type of camera lens provides the widest field of view for covering large open areas? → Wide-angle (2.8mm)
20. What is the risk of having too many 'master wafers' in a pin tumbler cylinder? → Increased risk of false keys (unauthorized keys accidentally operating the lock)
21. After drilling a safe and completing repairs, a CML should: → Plug the drill hole with a hardened steel insert and document the service
22. How should Certified Master Locksmith professionals handle procedures that have been updated or revised? → Review updates, complete required training, and implement revised procedures
23. Which document published by ASIS International provides guidelines for performing physical security assessments? → ANSI/ASIS PSC.1
24. How should Certified Master Locksmith professionals handle procedures that have been updated or revised? → Review updates, complete required training, and implement revised procedures
25. Which type of key system offers the highest security? → Restricted key system
26. What does 'all keys lost' mean for a modern transponder-equipped vehicle? → All programmed transponder codes must be erased and new keys programmed from scratch
27. When conducting a risk assessment for CML operations, which factor should receive the HIGHEST priority? → Probability and severity of potential harm
28. Why is key control important in locksmithing? → Prevent unauthorized duplication
29. In a master key system, 'selective master keying' means: → A key is masterkeyed to open specific locks chosen from across different groups
30. How should locksmiths handle confidential information? → Protect from unauthorized access