Interview guide for service and commissioning engineers

Most engineering interviews follow a similar pattern. Knowing what’s coming takes a lot of the nerves out of it.

The usual stages

• A phone or Teams screen, often with HR or a talent team. It’s about your background, your notice period, your right to work and what you’re looking for.
• A call or meeting with the hiring manager, usually the service or operations manager you’d work for.
• A technical interview with a senior engineer or technical lead.
• Sometimes a face-to-face visit, which may include a look round the site, workshop or facility.

Not every employer uses every stage. Ask your recruiter what the process is before you start.

The phone or Teams screen

Treat it as a proper interview, not a chat.

• Find somewhere quiet. Not in the van between jobs, and not while you’re driving.
• Have your CV in front of you, and make sure it’s the same version the employer has.
• Know your notice period and when you could realistically start.
• On Teams, check your camera and sound beforehand, and have a plain background.

The technical interview

This is where most engineers worry, and it’s usually fairer than they expect. Most technical leads want to see how you think, not whether you can recite a fault code for one model.

Expect questions like:

• Talk me through a fault you found recently, from the call to the fix.
• How would you put a UPS into maintenance bypass, or isolate it safely?
• How do you work under a permit to work, and what would make you stop a job?
• For cooling roles, how would you fault-find a chiller or CRAC unit that’s tripping, and what are your F-gas responsibilities?

If you’re not sure how deep it’ll go, ask your recruiter to find out. We’d rather brief you properly than have you guess.

Attitude counts

It’s easy to think the best-qualified engineer always gets the job. It doesn’t work like that. We recently saw an employer choose an engineer over technically stronger candidates because they liked his attitude.

Qualifications can be gained. Attitude, reliability and how you deal with customers are much harder to train.

Talk about your work, not just your CV

Some very good engineers undersell themselves because they’d rather show what they can do than talk about it. The interview is the one place you have to talk about it.

Before the interview, prepare two or three recent jobs you can walk through: what the problem was, what you did and how it ended. A real job described well beats a list of adjectives every time. Our piece on answering “tell me about yourself” goes into this in more detail.

What to bring

• Your driving licence.
• Proof of your right to work, or a share code if your status is online. Employers must check it before you start, so having it ready saves time.
• Your cards and certificates, or clear photos of them: ECS card, F-gas certificate, 18th Edition, IPAF or PASMA, SSSTS or SMSTS, whatever the role needs.

What to wear

For most service and commissioning roles, a shirt and smart trousers is right. You don’t need a suit unless you’re told otherwise. For senior or office-based roles, ask.

Questions to ask them

• What training would I get, and when?
• How big is the team, and who would I go to for support?
• What does a normal week look like, including travel and on-call?
• What happens between projects or when it’s quiet?
• Where could I be in a year’s time?

During and after

Stay positive about your current employer, even if you’re leaving for good reasons. If something comes up in the interview that doesn’t suit you, don’t show it. Tell your recruiter afterwards and let us deal with it.

Afterwards, call your recruiter the same day. How you felt it went is useful, and the sooner we speak to the employer the better.

If you’ve got an interview coming up, talk to us before you go in.

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Sources: gov.uk, Check a job applicant’s right to work; JIB, Electrotechnical Certification Scheme (2026); CITB, SSSTS and SMSTS; IPAF, PAL card; PASMA, Towers for Users.