Temporary Installations Practice Questions

C. Everything the code requires of permanent wiring applies, except where the article specifically modifies it

That default sits near the front of the article and every paragraph after it is either a named departure from it or an addition to it. Read it backward and a whole family of items becomes unanswerable, because you go looking for permission the article never grants. The reflex that works is to assume the ordinary rule applies and then check whether the article names the specific thing the question describes.

NEC 2026 590.4

D. Holiday decorative lighting and similar purposes

The 90 days is the only figure in days the time constraints contain, and it belongs to the seasonal category alone. A day count in an Article 590 item is doing one job, which is checking whether you hang the 90 days where it belongs or on a job trailer where it does not. Every other permitted use runs for as long as the work or the condition lasts.

NEC 2026 590.5(B)

B. For the period of the work, with no day count stated

No calendar attaches to the construction category anywhere in the article. What ends the permission is completion of the work rather than the passage of time, which is why the removal sentence matters more here than a date would. Hanging the 90 days on a construction site is wrong twice over, since construction has no day count and the 90 days belongs somewhere else.

NEC 2026 590.5

A. It is removed immediately upon completion of the construction or of the purpose it was installed for

This is the cleanest example of the point the whole article is making, which is that temporary describes a condition with a beginning and an end rather than a quality of workmanship. On an exam the item describes an installation that was compliant while the job was running, tells you the job finished, and asks about its status. The answer is not about how it was built, it is about the permission having expired.

NEC 2026 590.5

D. Emergencies, and tests, experiments and developmental work

Emergencies share one subsection with tests, experiments and developmental work, and no period attaches to any of them, so load testing a standby generator and a flood that took out the service sit in the same paragraph. Decorative lighting is the seasonal category with the 90 days on it, whatever the display is called. An item that asks whether one of these has a clock on it is checking exactly this.

NEC 2026 590.5

C. They are all of the grounding type, and they are not installed on any branch circuit that supplies temporary lighting

Keeping receptacles off the lighting circuits means one tool faulting does not put everybody in the dark, which is a safety rule wearing an inconvenience. The grounding-type requirement has no exception, and where the raceway or cable armor does not qualify as an equipment grounding conductor, a separate equipment grounding conductor runs with the circuit. Ground-fault protection is an addition here rather than a substitute for grounding.

NEC 2026 590.6(C)

A. They are protected from accidental contact or breakage by a guard

The guard is an addition to the ordinary rules rather than a relaxation of them, and where the guard is metal and secured to conductive enclosure parts it gets connected to the circuit equipment grounding conductor. One exception releases nonreplaceable LED lamps that are integral to a listed temporary lighting string. Treating ground-fault protection as the only addition in the article is what costs items like this one.

NEC 2026 590.6(E)

B. It is listed and labeled on the product

The listing requirement is a short section near the front of the article and it pairs with the 90 day limit in the time constraints, which is the other rule aimed at the same installations. The wet location and ground-fault answers are real requirements in other places and neither is what this section says. The 30 day figure does not appear in the article at all.

NEC 2026 590.2

B. They may be used in any dwelling, building or structure without limitation by building construction type and without concealment within walls, floors or ceilings

The relief in this article runs to getting conductors from the panel to the work, and this is the clearest example of it, since both of the ordinary limits on these cable types come off. Type SE gets the same treatment and may also be run in a raceway in an underground installation. None of that touches overcurrent protection, which still comes out of Article 240.

NEC 2026 590.6(A)

A. In an approved power outlet, switchgear, switchboard or enclosed panelboard, motor control center, or fused switch enclosure

The list is closed and it is the first thing to check when a stem describes a spider box or a homemade panel. Conductors may be cable assemblies or multiconductor cord or cable of the hard usage or extra-hard usage types, and they still get overcurrent protection out of the ordinary sections. An exception permits single insulated conductors for the emergency and test category where they are accessible only to qualified persons.

NEC 2026 590.6(B)

D. A suitable switch or plug connector that disconnects all ungrounded conductors of each temporary circuit, with a means to open a multiwire branch circuit simultaneously

Each temporary circuit gets a way to disconnect its ungrounded conductors, and a multiwire branch circuit gets a way to open all of them at once at the power outlet or panelboard where it originated. Identified handle ties are permitted for that. Plug connectors count, which is the part people miss when a stem describes cord-connected distribution.

NEC 2026 590.6(D)

C. Where the circuit conductors being spliced are all from nonmetallic multiconductor cord or cable assemblies and equipment grounding continuity is maintained

The general rule still wants a box with a cover installed, and the construction site exception is written around the cable type and the grounding path rather than around the connector or the location. A parallel condition covers metal-sheathed cable assemblies terminated in listed fittings that mechanically secure the sheath. Both conditions are about keeping the fault current path intact when the enclosure comes off.

NEC 2026 590.6(F)

A. On the floor or on the ground

The support paragraph asks for intervals that keep the run from physical damage, using staples, cable ties, straps or similar fittings, and then refuses the floor and the ground outright for branch circuits and feeders. Extension cords are excused from that paragraph, which is the distinction a stem will turn on. Runs through doorways and other pinch points are permitted with protection provided rather than forbidden.

NEC 2026 590.6(I)

B. Only for holiday lighting arranged with strain relief or other approved means so movement of the vegetation does not damage the conductors

Vegetation is off the list for branch circuits and feeders generally, and the single exception belongs to the seasonal category and comes with conditions on how the span is rigged. That is one of the few places the article grants something the permanent rules refuse outright. Span length and cord type do not buy it.

NEC 2026 590.6(I)

C. All 125 volt, single-phase, 15, 20 and 30 ampere receptacle outlets that are not part of the permanent wiring and are in use by personnel

The ratings are specific and 30 amperes is on the list, which surprises people who carry the figures over from the general chapters. Read the voltage and ampere ratings out of your own copy rather than a remembered list, because the two sections are written separately and have not always matched. The paragraph reaches receptacles in use by personnel, which is the condition rather than the rating.

NEC 2026 590.7(A)

D. Yes, the article gives receptacles installed or existing as permanent wiring their own paragraph with the same protection

This is the feature that catches people, because the protection is not limited to receptacles installed as part of the temporary wiring. What triggers it is the use rather than the installation, since the site is wet, the tools take a beating and the cords get run over. An exception permits a listed cord set or device incorporating listed ground-fault protection and identified for portable use.

NEC 2026 590.7(A)

D. A temporary wiring method is acceptable only where approved on the basis of the conditions of use and any special requirements of that installation

Approval based on conditions of use is written into the article, which is why the same detail can land two ways on two sites. That is a real feature of the section rather than an inconsistency to be argued away. It sits immediately beside the sentence saying the rest of the code still applies, and the two are meant to be read together.

NEC 2026 590.4

C. Listed ground-fault circuit-interrupter protection for personnel on the 15, 20 and 30 ampere receptacle outlets that are part of the generator

The paragraph reaches generators of 15 kW or smaller and names 125 volt and 125/250 volt single-phase outlets at 15, 20 and 30 amperes. An exception permits a listed cord set or device with ground-fault protection identified for portable use, but only where the generator was manufactured or remanufactured before 2015. Receptacles used in damp or wet locations carry the ordinary wiring device requirements in addition to this.

NEC 2026 590.7(A)

B. A written assured equipment grounding conductor program, continuously enforced at the site by designated persons

The distinction an item wants here is that this is a program somebody runs rather than a thing you screw into a box, so a candidate carrying a rule of thumb that Article 590 never relaxes protection will strike this answer out and lose the mark. Ground-fault protection is still the other option in the same paragraph. The program covers cord sets, receptacles that are not part of the permanent wiring, and cord- and plug-connected equipment.

NEC 2026 590.7(B)

A. Before first use on site, where there is evidence of damage, before equipment is returned to service after repairs, and at intervals not exceeding 3 months

Four triggers, and the recurring one is 3 months rather than a month or six. Every equipment grounding conductor is tested for continuity and every receptacle and attachment plug is tested for correct attachment of the grounding conductor. The results are recorded and made available to the authority having jurisdiction, and so is the program document itself.

NEC 2026 590.7(B)

C. In industrial establishments only, where only qualified personnel are involved, and only for outlets supplying equipment that would create a greater hazard if power were interrupted or whose design is not compatible with that protection

The exception is narrow on three axes at once: the kind of establishment, who works there, and what the outlet supplies. Read all three before answering, because a stem will satisfy one or two of them and leave the third out. Outside that exception, the receptacle paragraphs stand and the written program is the alternative only for outlets those paragraphs do not reach.

NEC 2026 590.7(A)

A. Suitable fencing, barriers or other effective means limiting access to authorized and qualified personnel

Guarding is one short section and it is the only place in the article where the voltage of the installation changes what is required. Access control is the whole of it, so the answer is physical rather than electrical. The other three options are real requirements elsewhere in the code and none of them is what this section says.

NEC 2026 590.8

D. They are current limiting

This section was written because temporary service equipment takes abuse and gets reused, and the current-limiting requirement is the article's answer to a high available fault current. The same section asks that previously used devices be examined to confirm they were properly installed and maintained and show no evidence of impending failure. Ground-fault protection of equipment on a service is a different rule in a different article with its own trigger.

NEC 2026 590.9

B. To the box with fittings listed for connecting flexible cords and cables to boxes designed for that purpose

The relief this article grants runs to wiring methods and to splices, not to the way a cord lands in a box that holds a device. The fitting has to be listed for that job and the box has to be designed for it, which rules out a tie or a generic connector chosen on diameter. This sits immediately beside the splice paragraph, so an item can put the two together and see which relaxation you reach for.

NEC 2026 590.6(H)

D. Find the rule by its heading, since at least one paragraph in the article sits at a different section number in this edition

The general requirements and the ground-fault requirements did not stay at the numbers an older tab points at, so a hunt by number on a timed exam is time you do not get back. The article is short enough to read front to back in one sitting, which is the argument for doing that once rather than trusting a tab. Ground-fault protection for personnel is still inside Article 590 and is written separately from the general chapter rule, so ratings do not carry from one to the other.

NEC 2026 590.6, 590.7