Equipment for General Use — Electrician Practice Questions

Why B is correct

Article 430 directs you to the motor full-load current tables, not the nameplate, whenever you size conductors, switches, and branch-circuit short-circuit and ground-fault devices. Using one standardized table value keeps every motor of a given horsepower and voltage on the same conductor and breaker, no matter which manufacturer built it.

What this question is testing

This question checks whether you can keep the two motor current sources separate in your head: table current drives conductors and short-circuit protection, nameplate current drives overload. Nearly every motor calculation on the exam starts with picking the right one, so a mistake here cascades through the rest of the problem.

On the job

A 10 hp 460-volt motor may be nameplated anywhere from about 12 to 13.5 amperes depending on the maker, but the table value stays constant. If the crew sizes conductors off nameplate and the customer later swaps in a different brand of the same horsepower, the circuit no longer complies. Sizing from the table means the conductors and breaker are already correct for any replacement motor of the same rating, which is why service shops can change a motor without pulling new wire.

Memory technique

Table for the wire, nameplate for the heater.

Exam tip

Read the stem for the words conductors or branch-circuit protection and reach for the table; read overload and reach for the nameplate.

Where to look it up

Article 430 Part I general provisions, the section on how motor full-load current is determined, then the motor full-load current tables at the end of Article 430.

Why C is correct

A separately derived system needs its own neutral-to-ground connection so that a line-to-ground fault on the secondary has a low-impedance path back to the derived source. Article 250 requires that system bonding jumper at exactly one location, plus a grounding electrode conductor from that same location to a suitable electrode.

What this question is testing

This tests recognition of a separately derived system and the three pieces that make it work: a single system bonding jumper, a grounding electrode conductor, and the supply-side bonding jumper carrying fault current back to the source.

On the job

Buildings with a stray-voltage or noisy-ground complaint frequently turn out to have a transformer bonded in two places, typically once at the transformer and again in the downstream panel where an installer left the factory bonding screw in place. Pull the covers, find every neutral-to-ground connection, and leave exactly one. Also confirm the grounding electrode conductor is sized from the largest derived ungrounded conductor and lands on a qualifying electrode such as building steel or a metal water pipe near the transformer.

Memory technique

One system, one bonding jumper, one electrode connection.

Exam tip

If the question says no direct electrical connection between primary and secondary conductors, it is a separately derived system, which brings the whole Article 250 derived-system package.

Where to look it up

Article 250 Part II, the section on grounding separately derived alternating-current systems, and the sizing table for the grounding electrode conductor of a derived system.

Why A is correct

A non-IC recessed luminaire relies on convection through the ceiling cavity to shed heat from its housing and driver. Article 410 protects that airflow by keeping insulation 3 inches away and out of the space directly above the fixture, unless the luminaire carries an insulation-contact identification.

What this question is testing

This tests whether you know the insulation clearance for recessed luminaires and can distinguish the Type IC listing from the separate half-inch clearance from combustible material that applies to the same fixture.

On the job

This shows up as a callback in the first winter after an energy retrofit, when blown-in attic insulation buries older non-IC cans and the thermal protectors start cycling the lights on and off. The fix is either restoring the 3-inch clearance with a rigid dam around each fixture or replacing the luminaires with IC-rated units. On new work, specify IC-rated airtight fixtures from the start, since energy codes push toward deep insulation and someone eventually blows over everything in the attic.

Memory technique

No IC marking means the insulation stays 3 inches back and never sits on top.

Exam tip

Two different recessed-luminaire clearances exist: 3 inches to insulation and a half inch to combustible material. Read which one the stem is asking about.

Where to look it up

Article 410 Part XI, clearance and installation requirements for recessed luminaires, covering both combustible material and thermal insulation.

Why B is correct

The rule gives two acceptable ways to guarantee the servicer controls the energy source: either the device is visible from the appliance, or it can be locked open so nobody restores power while work is underway. Both conditions target the same hazard from different directions.

What this question is testing

This tests the two-part appliance disconnect rule and whether you can distinguish real disconnect control from circuit identification. The same in-sight-or-lockable structure recurs for motors, air conditioning equipment, and heating equipment.

On the job

Attic fans, ceiling heaters, water heaters, and disposals all raise this question during rough-in. Field practice is simple: if the panel is not visible from the equipment, either install a local switch at the appliance or specify a breaker with permanently installed lockout provisions. Note that the locking means must stay attached to the breaker or panel when the lock is off, which rules out the loose lockout devices some technicians carry in a pouch. A local switch is usually cheaper and never gets argued about at inspection.

Memory technique

See it or lock it, otherwise install a switch at the appliance.

Exam tip

In sight or lockable open is a pattern that repeats through the Code. Learn it once and apply it across articles.

Where to look it up

Article 422 Part III, the appliance disconnecting means sections, plus the general lockable-disconnect requirements in Article 110.

Why B is correct

The disposer cord range of 18 to 36 inches is short enough to prevent excess cord from coiling in the cabinet and long enough to let the unit drop out of the mounting ring for service. It is one condition among several, including the grounding-type plug and an accessible receptacle.

What this question is testing

This checks whether you know the specific cord-and-plug allowances that make an appliance connection legal, and whether you keep the disposer range separate from the dishwasher and compactor range.

On the job

Under a kitchen sink you often have a disposer and a dishwasher sharing the same cabinet, each with a different permitted cord range and its own receptacle rules. Mount the receptacle in the adjacent cabinet or on the side wall so it stays accessible and away from the drain, use the correct kit cord with the strain relief the appliance provides, and keep the plug end out of the wet zone under the trap. Local amendments sometimes address dishwasher receptacle placement, so confirm with the inspector on new construction.

Memory technique

Disposer measures in inches, 18 to 36; dishwasher measures in feet, 3 to 4.

Exam tip

Learn the three appliance cord ranges as a set, since exam questions routinely swap one appliance for another while keeping the same numbers.

Where to look it up

Article 422 Part II, the section on flexible cord connections for specific appliances, with separate paragraphs for disposers, dishwashers, and trash compactors.

Why A is correct

The requirement is that switching take place in the ungrounded conductor so that opening the switch actually de-energizes the load. A device that opens every circuit conductor at the same moment is acceptable because there is no interval during which the load sits energized through an unswitched ungrounded conductor.

What this question is testing

This checks a foundational safety rule and the way the Code writes its narrow allowance for multipole devices. Candidates who read the allowance as a general permission to switch the grounded conductor pick the wrong answer.

On the job

Older two-wire switch loops and hurried remodels produce switched neutrals more often than anyone likes to admit, and the symptom is a lighting circuit that reads zero volts across the lamp but 120 volts from the shell to a ground rod. Somebody eventually finds it with a knuckle. When a service call reports a tingle from a light fixture that is switched off, a switched grounded conductor is near the top of the list, right alongside a broken grounded conductor upstream.

Memory technique

Switch the hot; the white stays put.

Exam tip

Read the phrase all conductors simultaneously carefully. That is the only door the Code opens for switching a grounded conductor.

Where to look it up

Article 404, the opening sections on switch connections, covering three-way and four-way switching and grounded conductors.

Why A is correct

The Code puts the burden on the product marking and on the installation together. The luminaire must carry a marking identifying it as suitable for wet locations, and it must be installed so that water cannot enter or accumulate in wiring compartments, lampholders, or other electrical parts. A damp-location fixture is a lesser rating and does not qualify.

What this question is testing

This tests the pairing of location classification with product marking, a pattern the Code repeats for boxes, receptacles, enclosures, and conductors. Recognizing the pattern lets you answer several questions from one idea.

On the job

The classic failure is a decorative fixture chosen by an owner or designer from a catalog and installed under an open soffit or on an exposed post. It fills with water, the lamp base corrodes, and the ground-fault device on the circuit starts tripping in every rainstorm. Field crews should check the label before hanging the fixture, because once the trim is up and the owner has paid for it, replacing it is a conversation nobody wants. Fixture orientation matters too: many listed wet-location fixtures are only rated when mounted in a specific position.

Memory technique

Wet outside, wet-rated label inside.

Exam tip

When a stem gives you a location classification, your first move is to look for the marking requirement that goes with it.

Where to look it up

Article 410, the early sections on luminaires in specific locations. Confirm which classification applies using the damp and wet location definitions in Article 100.

Why A is correct

Controllers are selected on horsepower at the applied voltage, and that rating must not be lower than the motor horsepower. Rating by horsepower rather than amperes builds the switching duty and the inrush withstand into the selection, which a plain ampere rating would not capture.

What this question is testing

This tests whether you know the unit a controller is rated in and that the rating is voltage-specific. It also checks that you do not carry motor protection percentages over into controller selection.

On the job

Undersized starters are one of the more common causes of repeat motor troubles on process equipment. A contactor asked to break more than its rated horsepower welds its tips or erodes them until the motor single-phases, and the symptom that reaches the electrician is a hot motor and a tripping overload, which sends people looking at the motor rather than at the starter. When replacing a failed starter, always check the horsepower rating at the actual system voltage rather than assuming the physical size tells you the rating.

Memory technique

Controllers speak horsepower, at a stated voltage.

Exam tip

Motor questions each have their own basis: horsepower for controllers, table full-load current for conductors, nameplate current for overloads.

Where to look it up

Article 430 Part VII, motor controllers. The horsepower ratings themselves come from the motor full-load current tables at the end of the article.

Why B is correct

A branch-circuit selection current appears on the nameplate when the manufacturer wants the circuit sized above the compressor rated-load current, typically because a protective device inside the unit is set to allow a higher continuous current. When that value is marked, the Code substitutes it for the rated-load current in every sizing step for the circuit and its equipment.

What this question is testing

This tests careful nameplate reading, which is what Article 440 is really about. The exam wants to see whether you know that a branch-circuit selection current, when present, displaces the rated-load current everywhere.

On the job

Rooftop units and heat pumps are usually installed against a nameplate that lists a minimum circuit ampacity and a maximum overcurrent device, which the manufacturer already derived from these rules. Trouble starts when a unit is field assembled or when a compressor is replaced and the installer works from the compressor label alone. Reading the wrong current off a nameplate that carries three of them yields a conductor one or two sizes small and an overcurrent device that nuisance trips on hot afternoons, which is precisely when the equipment is needed.

Memory technique

If a selection current is marked, it wins.

Exam tip

On air-conditioning questions, scan the nameplate data in the stem first and ask which currents are marked. That decides which rule applies before any arithmetic starts.

Where to look it up

Article 440 Part I, the sections covering marking on hermetic motor-compressors and the ampacity and rating provisions that follow.

Why A is correct

Two numbers separate the initial selection from the maximum increase. The initial device is 125 percent of nameplate for this motor class, or 42.5 amperes. Where that proves insufficient, the maximum permitted increase is 140 percent, or 47.6 amperes. The motor class that only qualifies for 115 percent initially is capped at 130 percent on the increase.

What this question is testing

The item tests whether the candidate can distinguish the initial overload selection from the maximum permitted increase, and match the correct ceiling to the motor's nameplate markings.

On the job

Nuisance overload trips on hard-starting loads such as conveyors, compressors, and loaded fans are a daily service call. The wrong response is to jumper the overload or install the largest heater in the drawer. The Code gives a defined ceiling, and if the motor still trips at that ceiling the problem is mechanical, a supply voltage issue, or a genuinely overloaded machine, all of which need investigating rather than a larger heater.

Memory technique

Start at 125, and if it trips you may go to 140. Never past it.

Exam tip

Two ladders in one section: 125 and 115 percent for selection, 140 and 130 percent for the increase. The nameplate decides which rung.

Where to look it up

Look in the motors article, in the overload protection part, at the section on continuous-duty motors and the subsection permitting an increased selection.

Why D is correct

Three ideas in one place: all ungrounded conductors open together, no pole operable by itself, and clear indication of position. The grounded conductor is generally not switched. Distance requirements are covered by separate sections on disconnect location, which use the in sight from concept rather than a fixed 6-foot figure.

What this question is testing

The item tests recall of the basic design requirements for a motor disconnect and whether the candidate recognizes single-phasing as the hazard behind the prohibition on independent poles.

On the job

Single phasing from a partially opened disconnect, a blown fuse, or a loose lug is one of the most common causes of motor failure in plants. The disconnect design rules address the part the electrician controls. In the field the practical companions are checking that the handle position indication is legible after painting, and that the switch is not jammed by a locking device that lets it sit between positions.

Memory technique

All the hots at once, and a handle that tells the truth.

Exam tip

Disconnect questions split into two families: what it must do electrically, and where it must be located. Answer the one being asked.

Where to look it up

Look in the motors article, in the part on disconnecting means, at the sections covering what the disconnect must open and how it indicates position.

Why B is correct

The trigger is either condition: more than 60 amperes, or more than 150 volts to ground. Meeting one is enough. Once triggered, the disconnect must be readily accessible and lockable in the open position, with the locking means remaining in place with or without the lock installed.

What this question is testing

The item tests whether the candidate can apply a two-part trigger where either condition suffices, and knows the specific attributes the disconnect must have.

On the job

Commercial charging installations are growing fast and are almost always remote from the electrical room, sometimes on a different level of a garage. Without a local lockable disconnect, servicing the unit means coordinating with building staff to find and lock out a breaker somewhere else. The disconnect also matters for emergency responders. On dwelling installations the smaller equipment usually falls below the thresholds and no separate disconnect is required.

Memory technique

Over sixty amperes or over 150 volts to ground: readily accessible and lockable.

Exam tip

When a rule says more than X or more than Y, either one alone triggers it. Do not look for both.

Where to look it up

Look in the electric vehicle power transfer system article, in the part covering equipment construction and installation, at the disconnecting means section.

Why A is correct

The rule sets a measurable performance requirement: 50 volts or less in one minute for units rated 1000 volts and below. Higher-rated capacitors get a longer allowance. The discharge means must operate automatically, which is why the section also prohibits relying on a manual switching operation to start the discharge.

What this question is testing

The item tests recall of a specific performance requirement expressed as a voltage and a time, and whether the candidate understands why the discharge must be automatic.

On the job

A disconnected capacitor bank can hold a lethal charge, and the person opening the door is often not the one who switched it off. The Code requires the discharge to be automatic for that reason. Field practice still calls for verifying with a meter and grounding the terminals before touching them, because discharge resistors fail open silently and nothing about the enclosure will tell you that it has happened.

Memory technique

Fifty volts in one minute, all by itself.

Exam tip

Capacitor questions almost always turn on stored energy: how much, how fast it drains, and whether draining is automatic.

Where to look it up

Look in the capacitors article at the section covering the drainage of stored charge.