Interview Questions to Ask an Electrical Engineer
For hiring managers, engineering leads and recruiters choosing interview questions to ask an electrical engineer candidate, whether the role is board-level electronics, controls or power. The list follows the order a good interview takes: background, circuit and power fundamentals, design and test work, tools and standards, troubleshooting, then working with other disciplines. Several questions fit only one kind of role, such as motor starting and arc flash studies for power work or mixed-signal layout for electronics, and their notes say when to leave them out.
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The questions
Each question, and why to ask it
Background
Describe the electrical work you do now. What do you design, and at what voltage and power levels?
Why ask it
One job title covers someone laying out 3.3-volt logic boards and someone specifying medium-voltage switchgear, so place the candidate before you test them. A strong answer has numbers in it: volts, amps, kilowatts, board layers or panel counts. If their range sits far from yours, say so now and hear what they think would carry over.
Which project on your resume are you proudest of, and what exactly was your part in it?
Why ask it
Pride shows what they think good engineering is: a clean design, a hard fault found, a product that shipped on time. Follow with what they would do differently now. An engineer who did the work can name a flaw in it straight away, while one who watched from the next desk tends to describe the product instead of the decisions.
Which area do you know best (power, controls, analog, digital, embedded or RF), and where does your knowledge run thin?
Why ask it
Nobody is deep in all of these, and a claim to be is a reason to probe harder in the technical section. Match the strong area to what your role needs daily and the thin one to what it needs twice a year. A named gap with a way of covering it, such as a colleague, an application note or a course, is a good sign.
Why did you choose electrical engineering, and which part of the work still holds your interest?
Why ask it
It is a warm-up, but the second half earns its place. People who light up about bench work will be restless in a role that is mostly specifications and vendor calls, and the reverse is just as true. Compare what they name with what the job's ordinary week really contains.
In your last role, how did your time split between the bench or lab, the field or plant floor, and a desk?
Why ask it
Have them answer for the past few months, since a career average hides what they do now. An engineer who has only simulated may freeze the first time a prototype smokes, and one who has only commissioned may find a year of design reviews slow going. Neither rules anyone out; it tells you what the first six months of support should cover.
Are you a licensed or chartered engineer, or working toward it, and have you ever had to sign or stamp work yourself?
Why ask it
Whether a license matters depends on the country or state, the industry and what the role has to sign or stamp, so check your own requirements before treating this as pass or fail. Where it is optional, the useful part is why they pursued it or chose not to. If the job depends on it, confirm the registration with the body that issued it, as you would any credential.
Fundamentals
How would you explain the difference between AC and DC to a new technician, and where have you worked with each?
Why ask it
This is the standard opener for the technical part, and the plain-language framing is what makes it worth the time. You want direction of current, why AC suits transmission and transformers, and why electronics and batteries run on DC, in words a newcomer could repeat. A textbook definition with no example from their own work suggests the knowledge stopped at the exam.
Take a circuit you have worked on and show me where Ohm's law and Kirchhoff's laws did real work for you.
Why ask it
Hand over a pen and paper. Reciting V equals IR shows little, but sizing a pull-up resistor, working out a divider or tracing where the current at a node goes shows the laws are tools they reach for. Hesitation here from an experienced candidate is worth a second basic question before you move on.
What is power factor, why does a facility care about it, and how would you correct a poor one?
Why ask it
The core of it is the ratio of real power to apparent power, the extra current that inductive loads such as motors draw for the same useful work, and capacitors as the usual correction. Stronger candidates add a caution about harmonics from drives and about overcorrecting. How a utility bills for it varies, so ask how it worked on the sites they know.
How does a transformer work, and what do you look at when you select one?
Why ask it
The principle should take two sentences: a changing current in one winding induces a voltage in the other, in proportion to the turns. Selection is where experience shows: kVA rating, impedance, inrush, cooling and the kind of load it will feed should all come up without prompting.
Why are large loads fed with three-phase power, and how do line voltage and phase voltage relate?
Why ask it
For power, facilities and motor-control roles this is the floor. Smoother power delivery, less copper for the same load and a rotating field for motors are the reasons to hear, along with the square root of three in a wye connection. For a board-level electronics role you can leave it out and lose nothing.
How would you choose between starting a motor across the line, with a soft starter or with a variable frequency drive?
Why ask it
The question exists because a motor started directly draws several times its running current for a moment. A sound answer begins with the load: a pump or fan that gains from speed control points to a drive, a conveyor that only needs a gentle start to a soft starter, and a small motor on a stiff supply may need neither. Candidates who have installed drives bring up cable length, harmonics and whether the motor is rated for drive duty. Leave it out for board-level roles.
What is the difference between grounding and bonding, and what goes wrong when either is done badly?
Why ask it
Terms differ by country (some say earthing), so listen for the ideas: a reference to earth, and metal parts tied together so a fault has a low-impedance path that operates the protection. Good candidates bring up both shock and noise, with a ground loop or a floating enclosure they have met. Vague talk of 'safety' with no mechanism is thin.
When would you protect a circuit with a fuse and when with a breaker, and how do you make sure the device nearest the fault opens first?
Why ask it
The first half has reasonable answers either way: cost, speed, interrupting rating, whether anyone will be there to reset it. The second half is the real test, and the word to listen for is coordination, or selectivity, worked out from time-current curves. If a small fault in their design could take out the main supply, you want to know now.
How do you size a conductor for a given load?
Why ask it
Current alone is the beginner's answer. An engineer who has done it adds ambient temperature, grouping with other conductors, voltage drop over the run and the protective device upstream, and says which code table or standard they worked from. On a circuit board the same thinking shows up as trace width and temperature rise.
To switch a load from a logic signal, how do you choose between a bipolar transistor, a MOSFET and a relay?
Why ask it
Most lists ask how a transistor works; this asks for the decision that knowledge is for. Good answers weigh load current and voltage, how fast and how often it switches, whether the two sides need isolating, and whether the logic pin can drive the gate fully on. Then have them estimate what the part dissipates when on: a candidate who multiplies current squared by on-resistance has sized one before.
Where analog and digital circuits share a board, what do you watch for?
Why ask it
This suits electronics roles more than power ones. Expect return current paths, where the converter's reference comes from, switching noise coupling into sensitive inputs, and sampling fast enough to avoid aliasing. An answer that stops at 'keep them apart' is a start; ask how they checked that the separation worked.
Tell me about a time capacitance or inductance you never drew in the schematic changed how a circuit behaved.
Why ask it
Parasitics separate engineers who have debugged real hardware from those who have only drawn it. Ringing on a long trace, a relay coil kicking back into its driver, a cable that behaved as a capacitor: any such story will do. No story at all from someone with several years at the bench is unusual, so ask what their test setup looked like.
Design and test
Take one design from the first requirement to release and tell me which decisions were yours.
Why ask it
Give this one ten minutes, because it carries more than any other question on the page. You should hear stages (requirements, architecture, schematic, layout or panel build, test, release) and at each one a choice they made and a reason for it. Interrupt once with 'why that part?' or 'why that topology?' and see whether the reasoning holds.
Tell me about a trade-off where cost, performance and schedule could not all win. What gave way?
Why ask it
Good engineers can say what they gave up and who agreed to it. Be wary of a story in which the candidate was right and everyone else was an obstacle, and equally of one in which nothing was sacrificed. Asking what the cheaper option would have cost later shows whether they ran the numbers.
How do you choose components, and what do you do when one goes obsolete or shows a long lead time halfway through a project?
Why ask it
Selection should include derating, a second source and a look at the part's lifecycle status, not only the headline specification. For the second half, a calm answer has steps: check for drop-in alternates, test the substitute, record the change. Owning a bill of materials for any length of time nearly always comes with a shortage story, so ask for theirs.
How do you make sure a design works at the edges of its tolerances and not just on a typical day?
Why ask it
The words to listen for are worst-case analysis, tolerance stacking, temperature range, supply variation and aging. Some will mention statistical simulation runs, which is fine as long as they can say what they varied. If the only evidence offered is that the prototype worked on the bench, ask at what temperature.
How do you handle heat in a design, and how do you check your estimate?
Why ask it
A solid answer starts with where the power is dissipated, moves through thermal resistance to a junction or enclosure temperature, and ends with a measurement by thermocouple or thermal camera. Adding a fan after the fact is a fix, not a method. This is also a natural point to ask how they worked with whoever designed the enclosure.
Before the first prototype arrives, what have you already decided about how it will be tested?
Why ask it
Engineers who plan testing early design in test points, jumpers and a way to power sections separately. The follow-up is what they would measure first and what result would make them stop. A candidate who starts thinking about test when the boards land usually also finds out then that a key node cannot be probed.
What was the last prototype or first build of yours that did not work, and what did you change?
Why ask it
First builds fail in some way for nearly everyone, so the honest answer is a specific one: a swapped footprint, a regulator that oscillated, a contactor wired to the wrong terminal. Credit the candidate who says what they changed in their own process afterward. 'Mine have generally worked' deserves a gentle second ask.
How have you dealt with electromagnetic interference, in a design or after a failed emissions test?
Why ask it
Experienced candidates talk about loop area, return paths, filtering at the connector, shielding and edge rates, and many have a story about a test lab. The best ones ran a rough scan of their own before paying for the formal test. If the answer is that a compliance group handled it, ask what that group sent back to them.
How do your designs get reviewed, and what did the last review catch?
Why ask it
You are checking two things at once: whether they are used to having their work examined, and how they take it. A real catch, told without defensiveness, is the good version. If no review has ever found anything, either the reviews were a formality or the candidate has stopped listening to them.
What do you do during design to make the product or panel easy to build and to service?
Why ask it
Contact with the people downstream shows up as detail: connectors that cannot be mated the wrong way, labels that match the drawing, room for a hand and a tool, fuses a technician can reach. A good follow-up is when they last watched their design being assembled. Engineers who have stood at the line draw differently afterward.
Tools and standards
Which schematic, layout or electrical CAD tools have you used, and what did you produce in each?
Why ask it
A list of product names is cheap. Ask for the output: a six-layer board, a set of panel drawings, a one-line diagram, and roughly how many sheets. If they have not used your package, the question becomes how long their last switch between tools took, and a few weeks of learning is rarely a reason to pass on a strong engineer.
Which simulation tools do you rely on, and when did a simulation last disagree with your measurement?
Why ask it
Circuit simulators, math and modeling packages and power system study software all count, depending on the field. The disagreement is the part to press on, because it shows whether they understand what the model leaves out. An engineer who has never seen the two differ has not been measuring.
Which bench instruments are you comfortable with, and how do you know a measurement is telling you the truth?
Why ask it
Multimeter and oscilloscope are the minimum for most roles. The second half is where skill shows: probe grounding, loading the circuit, bandwidth, and knowing that a grounded scope clipped to the wrong node makes a short. If you can, put an instrument on the table and ask them to set it up.
Before you work on or near energized equipment, what steps do you take?
Why ask it
The sequence matters more than the vocabulary: isolate, lock and tag, prove the meter on a known live source, test for absence of voltage, prove the meter again, and only then touch. Who writes that procedure and what protective equipment it calls for depend on the employer and local rules, so have them describe their last site's and compare it with yours. Treat any boast about working live to save time as a serious mark against, whatever else went well.
Which codes and standards governed your last project, and how did you work out which ones applied?
Why ask it
The right documents depend on the product, the market and the jurisdiction, so do not mark the answer against your own list. Mark the method: did they ask the customer, the test lab or the authority that inspects, and did they read the clauses themselves? 'The senior engineer told us' is acceptable from a junior and thin from a lead.
Have you taken a product or an installation through certification or inspection? What came back the first time?
Why ask it
Anyone who has been through it remembers the findings: a creepage distance, a missing marking, a temperature limit exceeded. How long the fix took and what the retest cost the schedule are details only someone who was there can give. If your role owns compliance, a candidate with one full cycle behind them starts well ahead of one who has only read the standard.
Have you run or used short-circuit, load flow or arc flash studies, and what did the results change?
Why ask it
This belongs in interviews for power and facilities roles; leave it out for circuit board work. Someone who has done the studies can say which software, where the input data came from and which breaker setting or label changed because of it. Reading a finished report is useful experience too, but it is a different level.
What have you programmed: PLCs, microcontrollers, or scripts for test and data?
Why ask it
Many electrical roles now include some code, and the answer shows how far they can go before handing off to someone else. The size of the largest thing they wrote, and whether anyone else had to maintain it, tells you more than a list of languages. For controls roles, follow with how they tested the logic before it ran a real machine.
How do you document a design so that someone else can build, test and maintain it without calling you?
Why ask it
Schematics with revision history, a bill of materials that matches them, test procedures and a record of why key choices were made are the core. Then find out what happens to the drawings after a change in the field. Red-lined prints that never make it back into the master set are a common and expensive habit.
How do you keep up with new components, tools and changes to the standards you work to?
Why ask it
Manufacturer application notes, standards updates, trade publications, a project at home: the source matters less than a recent example. Ask what they learned in the past year that changed a design. Revisions to standards in particular catch out engineers who learned one edition and never looked again.
Troubleshooting
A board or panel you designed shows no sign of life at first power-up. Talk me through what you do.
Why ask it
Method is the thing to grade. A careful engineer looks before measuring, limits the current, checks the supply rails in order and splits the system in half to find which side the fault is on. Swapping parts until something changes is the answer to worry about, as is reaching straight for the most exotic explanation.
What is the hardest fault you have ever had to find, and what turned out to be the cause?
Why ask it
Let them tell it in full and note the turning point: a measurement, a comparison with a good unit, a question to someone else. Luck is allowed, since most hard faults involve some. What counts is whether they can say why the earlier theories were wrong, which shows they understood the cause and did not just stop the symptom.
How do you go after an intermittent problem that will not show itself on the bench?
Why ask it
Good answers try to make the fault happen on demand with heat, cold, vibration, supply variation or a long logging run, and they collect evidence from the field about when it occurs. Ask how they would know it was fixed. With an intermittent, 'it has not come back yet' is not proof, and a careful engineer says so.
A motor keeps tripping its overload. What do you check, and in what order?
Why ask it
A grounded order is current on each phase against the nameplate, the overload setting, supply voltage and balance, then the mechanical load and how often the motor starts. Turning the setting up to stop the trips is the dangerous answer, since the device is doing its job. Use a fault from your own equipment if motors are not part of the role.
A control loop that behaved in testing starts to hunt or oscillate once it is installed. Where do you look?
Why ask it
Suited to controls, automation and drive roles. The grounded answer compares what changed between test and site before touching the tuning: a different load or inertia, a slower or noisier sensor, a valve or actuator that sticks or saturates, extra delay in the signal path. Retuning the gains first can hide a mechanical fault, so ask how they would tell the two apart.
A sensor reading is noisy. How do you work out whether the noise is in the signal, the wiring or your own measurement?
Why ask it
This rewards people who suspect their instrument first. Look for shorting the input to see the noise floor, moving or shielding the cable, checking the ground reference and using the frequency of the noise as a clue to its source. Adding a software filter before finding the cause hides the problem and does little else.
When a fix works and you cannot explain why, what do you do next?
Why ask it
The answer shows how they weigh schedule against understanding. Under real pressure, shipping the fix with the open question written down can be reasonable; pretending the question is closed is not. Strong candidates describe going back to remove the fix and see whether the fault returns.
Tell me about a failure in the field that traced back to your own design.
Why ask it
Ownership is what you are listening for. The good version covers how they found out, what they told the customer or their manager, and what changed in their checklist afterward. Give more credit for a real one, even an embarrassing one, than for a story where the root cause turns out to be somebody else's department.
Teamwork
How do you work with mechanical engineers when the enclosure, the cooling and the cable routing all want the same space?
Why ask it
Electrical work rarely ships alone, and this is where it most often collides. Look for early exchange of connector positions, keep-out areas and heat figures, and for a specific compromise they made. If the mechanical side always got it wrong in their stories, expect the same friction on your team.
Where hardware meets firmware or software, how do you settle whose problem a fault is?
Why ask it
The useful answer is that they find out together: a scope on the pin, a log from the code, both people in the room. Press for an occasion when the fault turned out to be on their side. Candidates who write a clear interface document, with pin functions, timing and default states, spare both teams a lot of argument.
How do you explain an electrical constraint to a project manager, a customer or an operator who is not an engineer?
Why ask it
Ask them to do it on the spot with something from their last project, such as why a cable cannot simply be made longer. Clear, short and free of jargon is the standard. It matters most in roles that face customers or the plant floor, where a misunderstood limit becomes a safety or schedule problem.
Tell me about a disagreement with another engineer over a design. How was it settled?
Why ask it
The best versions were settled by a test, a calculation or a prototype, with both people still on speaking terms. A candidate who can state the other person's argument fairly probably argued it fairly at the time. Settled by rank, or not settled at all, is worth one follow-up on what they would do if it came up again.
When technicians or electricians tell you a design cannot be built as drawn, what do you do?
Why ask it
You want someone who walks out to look. The people who build and wire the design see problems no review catches, and an engineer who treats their feedback as an interruption will keep repeating the same mistakes. Ask for a change they made to a drawing because of something a technician showed them.
Have you checked or guided the work of junior engineers or technicians? What do you look at first in someone else's design?
Why ask it
Worth asking for senior and lead roles, where much of the job is catching other people's errors before they are built. A practiced reviewer has a short list ready: ratings against worst-case stress, protection, connector pinouts, whatever is expensive to fix after release. Notice whether they describe explaining the problem or simply correcting it, because only the first leaves the junior better.
When two projects both need you in the same week, how do you decide what comes first, and who do you tell?
Why ask it
A general answer about lists and priorities tells you nothing, so ask for the last real collision. In this field the detail to hear is that anything with a safety consequence or a lead time, such as a long-delivery part to order or a lab slot to keep, goes first. The second half counts as much: a date that slips quietly costs the team more than one flagged early.
What would you like to ask us about the work, the team, the lab or the equipment you would be using?
Why ask it
End here and let them lead. The questions a candidate asks show what they think the work is, and an engineer who asks about your test equipment, review process or voltage levels has been picturing themselves doing it. Answer honestly: a hire who was oversold on the lab will find out in the first week.
How to interview an electrical engineer
Practical guidance for the conversation itself
Before the interview
Decide which kind of electrical engineer you need
The title covers circuit design, embedded hardware, controls and automation, power distribution and more. Before choosing questions, write down the voltage and power range of the work, whether it is mostly design, test or site work, and which tools the team runs. Then cut the list to match: three-phase power, motor starting, protection coordination and system studies for power and facilities roles; switching devices, mixed-signal layout and interference for electronics roles; the control loop and programming questions for automation.
Pick ten to twelve and keep them the same
An hour holds about ten or twelve of these with follow-ups. Take two or three from each group, and give every candidate for the role the same core set so that you are comparing answers and not interviews. Keep the others as spares for a second round.
If you are not an engineer yourself
Recruiters and HR partners can run Background and Teamwork well, and should leave Fundamentals to someone technical where they can. If you have to put a technical question alone, treat the note as a listening guide and write down what the candidate says in their own words for the engineering lead to read. Do not score an answer you could not follow.
Bring something real to the table
A schematic page, a one-line diagram or a photo of a panel from your own work, with anything confidential removed, gives better evidence than an abstract question. Ask the candidate what they notice, what they would check first and what they would want to ask its designer. If you plan a practical exercise, say so in the invitation, along with whether a calculator or notes are welcome.
In the room
Start with their work, then test it
Background questions settle nerves and tell you where to aim. If the candidate says they designed a motor drive, take your Fundamentals questions from motor drives. A question tied to something they claim to have done is fair to them and hard to bluff.
Ask them to draw
Offer a whiteboard or paper for anything about circuits. A sketch shows within a minute whether someone thinks in current paths and reference points or in memorized phrases. It also lets a quiet or nervous candidate show what they know without having to perform.
Follow each answer one level down
After a technical answer, ask why once: why that value, why that part, why that order. Stop when you reach either a clear explanation or a clear 'I do not know'. In a field with this much to remember, 'I would have to look that up, and here is where' is a good answer.
Respect what they cannot tell you
Much of a candidate's best work belongs to a previous employer. If they say a detail is confidential, accept it and ask about the method instead: how they approached the problem, what they measured, what went wrong. Pushing for proprietary detail tells them how you would expect them to treat your own designs.
Reading the answers
Numbers and units are a good sign
Engineers who did the work remember that the rail was 24 volts, the load drew 8 amps and the regulator ran too hot to touch. Round answers with no units, such as 'a high-power system', do not disqualify anyone, but they are the place to ask for one figure.
Separate 'I' from 'we'
Team projects are normal, and a candidate who credits colleagues is doing the right thing. You still need to know what this person did. When a story is all 'we', ask which calculation, drawing or test was theirs, and who checked it.
Weigh safety answers on their own
A forgotten formula can be forgiven. A casual attitude to isolation, lockout or working near live equipment is different, because the cost falls on other people. Decide before the interviews what answer on safety would end a candidacy for this role, and hold every candidate to it.
Score straight after
Write a short score for each group of questions within a few minutes of the candidate leaving, before you talk to the other interviewers. Then compare. Where two interviewers disagree about a technical answer, go back to what the candidate said, which is why it pays to write down their words and not your impression.
Mistakes to avoid
Running a trivia quiz
Formulas and definitions can be looked up in seconds on the job. An interview made only of Fundamentals rewards recent graduates and good memorizers and tells you little about whether someone can get a design built and working. Keep that group to a quarter of your time and spend the rest on work they have done.
Testing for your own specialty
A power engineer interviewing for an electronics role, or the reverse, tends to ask what they themselves know best. Check each technical question against the job description before the interview. If the role will never touch three-phase power or radio-frequency layout, a weak answer there should cost the candidate nothing.
Marking codes and licensing against one answer
Which codes apply, which edition is in force and whether a license is required differ by country, state, industry and client. Ask how it worked where the candidate has practiced, confirm your own requirements with whoever is responsible for compliance, and do not assume that a different answer is a wrong one.
Straying into personal territory
Questions about age, health, family plans, nationality and similar matters are restricted in many places, and the rules differ by location. Keep every question tied to the work, and ask your HR or legal contact what is allowed where you hire before adding any of your own.