Ten 442A Industrial Electrician questions in the format of the Red Seal exam: four options, one correct answer, no trick questions. They are free to use, print and share. There is nothing to sign up for on this page.
01How to use these
The questions come from the TicketPrep 442A bank and are spread across the exam's work activities in the order and roughly the proportion the Red Seal Program publishes for this trade: A (performs common occupational skills), B (installs and maintains generating, distribution and service systems), C (installs and maintains wiring systems), D (installs and maintains rotating and non-rotating equipment and control systems), E (installs and maintains signalling and communication systems), F (installs and maintains process control systems). Answer each one before opening the explanation. Every explanation covers all four options, because on the real exam the wrong options are written to be plausible, and knowing why they are wrong is most of the skill.
- Pace. The exam allows four hours for 100 questions, so about 2 min 24 s per question. Try these at that pace.
- Print. The printed version shows the questions and the answer key without the explanations, so it works as a handout. Download PDF
- Mark. The pass mark is 70 percent on every Red Seal trade; seven of ten here is the same bar.
02The questions
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In a flour mill's electrical room, a layer of flour dust has built up on the cable trays and on top of the MCC sections. How should the dust be removed?
- With a vacuum approved for combustible dust, bonded and grounded.
- By washing it down with a low-pressure hose, after locking out the MCC.
- By blowing it off the trays with compressed air at a reduced pressure.
- With an ordinary shop vacuum, fitted with a fine HEPA filter.
Show the answer
A. Correct. Flour is a combustible dust: a settled layer is the fuel for a secondary explosion once a disturbance throws it into the air. A vacuum approved for combustible dust collects it without raising a cloud, and bonding and grounding keep static from building on the hose and nozzle. Work from the top down so cleaned surfaces are not dusted again.
Why not the others
B. Water does not belong in an electrical room even with the gear locked out: it gets into buckets, bus and terminals, and wet flour turns into a paste that hardens and grows mould. The room is cleaned dry, with a vacuum approved for combustible dust.
C. Blowing down lifts settled dust into a cloud, the exact condition a dust explosion needs, and drives it into enclosures and onto lower surfaces. Lowering the pressure does not change that. Collect the dust with a vacuum approved for combustible dust instead.
D. The filter stops fine dust escaping, but it does not make the machine safe on combustible dust: an ordinary vacuum's motor and switch can ignite dust drawn inside, and its plastic hose can build static. Use a vacuum approved for combustible dust, bonded and grounded.
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A water treatment plant's new single-phase service runs underground in rigid PVC conduit from the supply authority's padmount transformer and enters the electrical room below grade. What does the CEC require at the conduit end inside the building?
- Fit an expansion joint where the conduit rises from grade.
- Fit a bonding bushing with a jumper to the service box.
- Seal it with a compound that keeps out moisture and gas.
- Slope it toward the building so it drains into the box.
Show the answer
C. Correct. Rule 6-300 requires a service conduit connected to an underground supply system to be sealed with a suitable compound, because the duct is a ready path for ground water and for gases to travel into the building and the service equipment. The seal goes in after the conductors are pulled.
Why not the others
A. An expansion fitting absorbs the thermal movement of exposed PVC runs. It does nothing to stop water and gas travelling through the duct into the building, which is what the CEC's service conduit seal is for.
B. A bonding bushing bonds a metal raceway to its enclosure where locknuts alone are not enough. This conduit is PVC, so there is nothing to bond; the requirement at an underground service entry is a seal against moisture and gas.
D. Sloping the duct toward the building delivers ground water straight into the service equipment. Underground ducts are sloped to drain away from the building, and the service conduit is sealed against moisture and gas.
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A 120 kVA online UPS in a generating station's control building must be fully isolated for service while its critical load stays powered. In what order is it put on maintenance bypass?
- Open the UPS output, close the maintenance bypass, then go to static bypass.
- Open the UPS input, let the battery carry the load, then close the bypass.
- Close the maintenance bypass, go to static bypass, then open the UPS input.
- Static bypass, close maintenance bypass, then open UPS output and input.
Show the answer
D. Correct. On static bypass the load is already fed from the bypass supply, so closing the maintenance bypass breaker adds a second path from the same source with no break. Only then are the UPS output, input and battery breakers opened, leaving the UPS isolated while the load runs on the maintenance bypass. Manufacturers' interlocks are usually built around this sequence.
Why not the others
A. Opening the UPS output first drops the critical load, because the maintenance bypass is not closed yet. The make-before-break order is static bypass, close the maintenance bypass, then open the UPS.
B. Running the load on battery adds risk for no gain: if the battery is weak, the load drops before the bypass is closed. The load moves to static bypass and then onto the maintenance bypass without depending on the battery.
C. Closing the maintenance bypass while the inverter carries the load parallels the inverter with the bypass supply, which can damage the inverter or trip the system. The UPS goes to static bypass first, so both paths come from the same source.
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At a pulp mill, a 400 A feeder made up of three single-conductor cables, one per phase, will enter the top of a steel splitter. How must the cables enter the enclosure?
- Through three separate holes in the steel top, each with a non-ferrous connector.
- Through three separate holes in the steel top, with the cables derated to 70 %.
- Through one common non-ferrous plate that replaces part of the steel top.
- Through one common steel plate with three holes and bonding bushings.
Show the answer
C. Correct. Each single AC conductor sets up an alternating magnetic field; steel left between separate holes forms a magnetic loop around each conductor and heats by induction. Rule 4-008 forbids individual openings in a ferrous box for single conductors carrying more than 200 A and requires all the conductors of the circuit to pass through one common non-ferrous or insulating plate.
Why not the others
A. Non-ferrous connectors help, but the steel web between three separate holes still surrounds each conductor with a magnetic path that heats by induction. Above 200 A the CEC does not allow individual openings in a ferrous box; the conductors share one non-ferrous or insulating plate.
B. Derating to 70 % is one of the CEC's remedies for sheath currents in single-conductor cables, not for heating of the box wall. Separate holes in steel still heat by induction; the conductors must enter through one common non-ferrous or insulating plate.
D. A steel plate is still ferrous: the metal between its three holes forms a magnetic loop around each conductor and heats. The common plate must be non-ferrous, such as aluminum, or insulating.
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Since a new LED wall pack was mounted beside the photocell on a warehouse wall at a distribution yard, the yard lights switch off and back on every few minutes all night. Covering the photocell by day turns the lights on normally. What is the cause?
- The LED drivers are overheating and shutting down.
- The photocell's built-in turn-off delay has failed.
- The photocell is seeing the new wall pack's light.
- The contactor is chattering on low control voltage.
Show the answer
C. Correct. When the yard lights come on, light from the wall pack reaches the photocell, which reads it as daylight and turns the lights off; in the dark it turns them back on, and the cycle repeats at the photocell's delay. Shield or re-aim the wall pack, or move the photocell, usually facing north, where only daylight reaches it.
Why not the others
A. Overheating drivers would not have started cycling the night a wall pack was mounted beside the photocell, and covering the photocell by day turns the lights on normally. The photocell is reacting to the new light.
B. The delay only sets how long the photocell waits before switching; it does not turn the lights off by itself. Light reaching the photocell from the wall pack is what turns them off each time they come on.
D. Chatter is a rapid buzzing, not a clean off-and-on every few minutes, and the circuit works normally when the photocell is covered. The new light falling on the photocell is the cause.
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At a sawmill, one branch circuit supplies three continuous-duty conveyor motors with full-load current ratings of 34 A, 22 A and 14 A, all of which can run together. Under the CEC, what is the minimum ampacity of the conductors supplying the group?
- 75.1 A
- 78.5 A
- 70.0 A
- 87.5 A
Show the answer
B. Correct. For a group of continuous-duty motors, Rule 28-108 sizes the conductors at 125 % of the largest motor's full-load current plus the full-load currents of all the others: 1.25 × 34 + 22 + 14 = 42.5 + 36 = 78.5 A. The 25 % margin is applied once, to the largest motor only.
Why not the others
A. This takes 115 % of the largest motor plus the others, which is the CEC's method for sizing a disconnecting means that serves a group of motors (Rule 28-602), not the conductors. Conductors take 125 % of the largest: 78.5 A.
C. This is the plain sum of the three full-load currents. The CEC adds a 25 % margin to the largest motor's current: 1.25 × 34 + 22 + 14 = 78.5 A, so these conductors would be undersized.
D. This applies 125 % to every motor (1.25 × 70 A). The CEC adds the 25 % margin only to the largest motor in the group and adds the others at their full-load current, giving 78.5 A.
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What does a regenerative (four-quadrant) SCR DC drive have in its armature circuit that a non-regenerative drive does not?
- A dynamic braking resistor across the armature.
- A field-weakening bridge for running above base speed.
- A second SCR bridge connected in inverse parallel.
- A freewheeling diode across the armature.
Show the answer
C. Correct. One SCR bridge passes armature current in one direction only. A second, reverse-connected bridge lets current flow the other way, so the drive can return a load's energy to the supply when braking or lowering and can drive the motor in both directions without reversing contactors.
Why not the others
A. Dynamic braking wastes energy in a resistor, usually switched in by a contactor on a stop, and can be fitted to a non-regenerative drive. A regenerative drive returns the energy to the AC supply through its second bridge instead.
B. Field weakening is done in the separate field supply and is available with either type of drive. Regeneration and reversing depend on the armature converter.
D. Freewheeling diodes are used in half-controlled (SCR and diode) bridges. They stop the armature voltage going negative, so they rule out regeneration rather than providing it.
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At a conventional detector base in a steel mill, the circuit's positive conductor has separate in and out terminals. An apprentice strips the middle of the unbroken conductor and wraps it under the in terminal only. How must it be terminated?
- Leave the loop and jumper the in to the out terminal.
- Cut it and land each end on its own terminal.
- Wrap the unbroken loop under both terminals.
- Cut it and land both ends under the in terminal.
Show the answer
B. Correct. The CEC's supervision rule (Rule 32-106) requires each conductor end at dual terminals to land on its own terminal. With the conductor cut, a loose or missing connection at that device opens the circuit and the panel shows a trouble; an unbroken loop keeps the circuit whole and hides the fault.
Why not the others
A. A jumper adds a second parallel path around the device, which defeats supervision even further: the circuit stays whole whatever happens at that base. Supervision depends on the conductor being cut so each end lands on its own terminal.
C. Landing the same unbroken loop under two screws still leaves one continuous conductor past the device, so a loose terminal or missing device would not open the circuit and the panel could not report it. The conductor is cut and each end landed separately.
D. Both cut ends under one screw are joined at that terminal, so the circuit stays whole past the device: a removed detector head or a loose base would never open it, and the panel could not report it. Rule 32-106 requires each end on its own terminal.
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A sawmill's log deck needs a photoelectric sensor to detect logs crossing a 5 m wide infeed, where sawdust hangs in the air and settles on every surface. Which sensing mode is selected?
- Diffuse with background suppression, mounted at the deck's edge.
- Diffuse, the sensor aimed across the infeed at the passing logs.
- Through-beam, emitter and receiver facing across the infeed.
- Retroreflective, the sensor on one side and a reflector on the other.
Show the answer
C. Correct. The light crosses the dusty air once, straight into the receiver, so through-beam has the most excess gain and the longest range of the photoelectric modes, and a log only has to block the beam, whatever its bark or colour. Put the lenses on a cleaning schedule and set the sensitivity with margin.
Why not the others
A. Background suppression is a diffuse mode that ignores objects beyond a set distance. It is meant for short ranges, still relies on light reflected from the log, and gains nothing in heavy dust.
B. A diffuse sensor depends on light bouncing back off the log itself. Dark, wet or ragged bark returns little light, and across a 5 m infeed the return is far too weak for reliable detection.
D. A retroreflective beam crosses the dust twice, out and back, and the reflector collects sawdust, so its range and margin are lower than through-beam. It suits shorter, cleaner spans where wiring one side only is the attraction.
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A level transmitter controlling the feed valve on a running pulp mill stock tank must be removed for repair. What is done before the transmitter is isolated or disconnected?
- Have operations put the level loop in manual control.
- Disconnect it and let the controller hold its last value.
- Jumper the transmitter terminals to keep the loop complete.
- Close the impulse line block valves at the tank.
Show the answer
A. Correct. In manual the controller output, and so the valve, stays where operations set it, and nothing reacts when the measurement drops out. Agree how the level will be watched, then isolate, de-energize and remove the transmitter; the loop returns to automatic only after it reads correctly again.
Why not the others
B. Whether a controller holds, fails high or fails low on a lost input depends on its configuration. Putting the loop in manual removes that uncertainty before anything is touched.
C. Shorting the transmitter terminals lets the loop current rise to the input's limit. The controller sees an over-range level and drives the valve accordingly.
D. Closing the block valves with the loop in automatic traps a false measurement that no longer follows the tank and can drift as the trapped pressure changes. The controller keeps acting on it and drives the feed valve while the real level moves, which can overflow or empty the tank. The loop goes to manual first.
03Answer key
| Question | Answer | Work activity |
|---|---|---|
| Q1 | A | Performs common occupational skills |
| Q2 | C | Installs and maintains generating, distribution and service systems |
| Q3 | D | Installs and maintains generating, distribution and service systems |
| Q4 | C | Installs and maintains wiring systems |
| Q5 | C | Installs and maintains wiring systems |
| Q6 | B | Installs and maintains rotating and non-rotating equipment and control systems |
| Q7 | C | Installs and maintains rotating and non-rotating equipment and control systems |
| Q8 | B | Installs and maintains signalling and communication systems |
| Q9 | C | Installs and maintains process control systems |
| Q10 | A | Installs and maintains process control systems |
04More free questions
For the 442A exam itself, the 442A exam guide covers the work activities, their weights and how the exam is scored, and the 442A Industrial Electrician practice exam page describes the full TicketPrep 442A question bank. The same free format is available for the other 13 trades, plus the free guides on the pass mark, question counts, exam day and how to study.
How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.
05Questions by exam block
Working on one part of the 442A exam? Each block has its own page with five more free questions, the tasks the block covers and their weights.