Ask about one actual work decision
Begin with: “What would you rule out before cutting into finished work to address a repeat leak?” Ask what evidence the person had, what they checked, who authorized the work and how they knew the result was acceptable. The same question can reveal disciplined process at different experience levels.
Probe an ambiguous situation
Give an ordinary scenario such as commercial inspection on rough-in. Ask what information they would gather before changing anything. Reward candidates who identify missing facts and boundaries. Do not turn the interview into a test of dangerous improvisation or ask them to describe bypassing safeguards.
Separate tasks from titles
Someone who has worked around residential service and emergency calls may not have led a project involving new construction, remodels and fixture installations. Ask which specific tasks they performed personally, which they assisted and which they have only seen. In a hiring process, clear limits are useful information, not grounds for embarrassment.
Check documentation and communication
Ask them to explain how they would record a handoff after recurring under-sink leak after repair. Could the next shift understand what happened? Would a customer or inspector understand the result? This helps distinguish candidates who complete work from candidates who can make the work verifiable.
Finish with mutual clarity
Tell candidates the actual shift, travel demands, supervision and tools supplied. Service dispatch, weekend emergencies and company vehicle terms are important. Use the same essential questions for every comparable applicant, document role-related reasons for decisions and avoid asking for protected personal details.