Interview guide for skilled trades: a loop for electricians, plumbers, HVAC technicians and welders

A skilled trades hire is judged on the job site, where a wrong assumption can start a fire, flood a ceiling or put someone in the hospital. Interviews that only ask "Tell me about yourself" miss the three things that matter most: whether the license is real, whether the candidate works safely when nobody is watching, and whether their diagnostic method is sound. This guide gives service managers and superintendents a loop for licensed and certified trades, built around a journeyman electrician for a service company, with adjustments for plumbers, HVAC technicians, welders, maintenance technicians and apprentices at the end.

The first calls are in electrician screening questions, plumber screening questions and HVAC technician screening questions. This page is the loop after the screen.

The loop at a glance

Stages 2 to 4 fit into one morning at the shop. Many trades candidates are working full time, so offer an early start or a Saturday slot.

Stage 1: screen and license check (20 minutes)

• "What license do you hold, in which state or city, and when does it expire?" Then verify it on the licensing board's own lookup before stage 2 and record the date you checked.
• "Walk me through a typical week: residential or commercial, service or new construction, and how many calls a day?" Listen for: a clear picture of the work that matches yours.
• "This role is on call [pattern] and drives a company van. How does that fit?" Ask every candidate the same way. If you check driving records, do it consistently and through a compliant process.

Stage 2: technical interview (40 minutes)

A lead technician asks about real jobs and two troubleshooting talk-throughs. Avoid code trivia; ask how they would find the answer instead.

1. "Tell me about the hardest fault you found in the last year. How did you find it?" Listen for: a sequence of tests, each one ruling something out, and confirming the fix.
2. Talk-through: "A customer says half the outlets in the kitchen stopped working after a storm. The breaker is not tripped. What do you do?" Listen for: verifying de-energized before touching, checking GFCI devices upstream, testing rather than guessing, and explaining findings to the customer.
3. Talk-through: "You open a panel and find aluminum branch wiring with signs of overheating at a device." Listen for: stopping, explaining the hazard to the customer plainly, and quoting the correct repair rather than patching it.
4. "When was the last time you looked something up in the code, and where?" Listen for: a specific question and a reliable source, including the locally adopted code edition.

Stage 3: the hands-on practical (60 minutes)

Run it on practice materials in the shop, never on a customer job. Write the task, the materials and the scoring sheet once, and use them for every candidate. If your practice involves trial shifts on real work, read how to run a job trial day first.

Example practical for an electrician

• Build (30 minutes): on a training board, wire a three-way switch circuit and a GFCI-protected receptacle from a simple drawing.
• Diagnose (20 minutes): a second board has two planted faults, such as a loose neutral and a miswired switch leg. The candidate finds and explains them with a meter.
• Explain (10 minutes): "Tell me what you checked and why, in the order you checked it."

What to score

• Safety habits: verifying de-energized with a tested meter before work, correct personal protective equipment, and no shortcuts when the clock runs down. A candidate who works a board they have not verified fails the gate.
• Workmanship: neat terminations, correct conductor sizing and connections, labeled work.
• Diagnostic method: one change at a time, and confirming each fault was the fault.

Under the ADA regulations at 29 CFR 1630.14(a), you may ask an applicant to describe or demonstrate how they would perform job-related functions, with or without reasonable accommodation. Give everyone the same practical and ask before the day whether they need an adjustment to the setup.

Stage 4: manager interview with a customer scenario (30 minutes)

1. Scenario: "The customer is upset that the repair will cost more than the quote because you found a second problem." Listen for: explaining what they found and why it matters, offering options, and getting approval before extra work.
2. "Tell me about a job where you made a mistake that needed a callback." Listen for: owning it, fixing it, and what they check now.
3. "Tell me about a time you stopped work because something was unsafe." Listen for: a real example, and that they did not restart until it was resolved.
4. "How do you close out a service call?" Listen for: clear notes, photos where used, parts recorded and the customer told what was done.

Scorecard competencies and weights

Example weights for a journeyman service electrician. Lock yours before the first candidate.

The scorecard builder prints one sheet per interviewer and checks the weights add up to 100.

Licenses and certifications: what is actually required

These points were checked against the linked primary sources as of October 2026. They are not legal advice; licensing rules vary by state and city.

• OSHA 10 and 30 cards are not certifications. OSHA's Outreach Training Program page says the classes are voluntary, do not meet the training requirements of any OSHA standard, and are not considered a certification, although some states, municipalities or others require outreach training as a condition of employment. Your own site-specific training duties still apply.
• HVAC and refrigeration: EPA Section 608. Under 40 CFR 82.161, anyone who could reasonably be expected to violate the integrity of the refrigerant circuit while maintaining, servicing, repairing or disposing of covered appliances must pass an exam from an approved certification program, by type (I, II, III or Universal). Ask which type and see the card.
• Crane operators. In construction, 29 CFR 1926.1427(a) requires the employer to ensure each operator is trained, certified or licensed, and evaluated before operating covered equipment.
• Electrical, plumbing and gas licenses are issued by states and, in some places, cities or counties. Verify at the issuing board's lookup and check that the license class covers the work you will assign.
• Background and driving checks through a vendor fall under the Fair Credit Reporting Act; see the FCRA background check process. Drug testing rules vary by state.

The decision rule

1. Gate 1: license verified at the source for the work you will assign.
2. Gate 2: no safety failure in the practical.
3. Floor: diagnostic method at 3 or above for journeyman roles.
4. Weighted total: in this example, 2.8 or higher on a 1–4 scale is an offer, subject to references.
5. Decide the same week. Good tradespeople are rarely unemployed for long.

Adjusting for other trades

Mistakes that weaken trades loops

• No practical. Talking about a fault is not finding one.
• Practicals on paying jobs. They are unfair to compare and expose the customer to an unknown worker.
• Treating cards as competence. A card shows training happened, not that safe habits stuck.
• Waiting a week. Agree the decision meeting before the practical.

After the hire, adapt the new hire 30-60-90 day plan template with ride-alongs in the first 30 days and solo calls by day 60.