Electrical
Temporary power field guide for construction sites
Set the temp service, hold the GFCI rule, keep the cords and lights safe, size the load, and document the daily checks before the permanent service energizes.
Direct answer
Temporary power is the electrical system that runs a construction site before the permanent service is energized, feeding the tools, lights, and trailers. OSHA and NEC Article 590 treat it as a high-shock environment, so 125 V, 15-, 20-, and 30-ampere receptacles in use by personnel need GFCI protection, or the site runs an assured grounding program instead.
Key takeaways
- NEC 590.6(A) requires GFCI protection on all 125 V, single-phase, 15, 20, and 30 A temporary receptacles in use by personnel.
- OSHA 1926.404(b)(1) gives two paths on temp power: GFCI or a written assured equipment grounding conductor program. Running neither is prohibited.
- Damaged, taped, or field-spliced extension cords come out of service; jobsite cords must be three-wire, hard or extra-hard usage like SOOW or SJTW.
- OSHA 1926.405 requires guards, cages, or enclosed lamps on every temp string light, and lights must not be suspended by their own cord.
- Bond a stand-alone generator feeding its own receptacles at the frame; bond a generator feeding a panel or transfer switch once at the system.
Temporary power, and why it has its own rules
Temporary power is the electrical system that runs a construction site before the permanent service is energized. It feeds the tool chargers and the corded tools, the task lights and the string lights, the field trailers and the gang boxes, the material hoist and the welders. It is the power for the build. Then the building gets its own service and the temp system comes out.
Why it gets its own rules comes down to the environment. Temp power lives outdoors and in the unfinished shell, in rain and mud and concrete dust, with cords dragged across rebar and run over by lifts, plugged and unplugged a hundred times a shift by people who are not electricians. It is the wettest, most abused, highest-shock wiring on the job, and the people using it have wet hands and steel boots on a conductive slab. That is exactly why OSHA and the NEC write temp power tighter than permanent wiring, not looser.
The rookie assumption is that because it is temporary, it can be sketchy. The code reads the other way. A finished, protected receptacle gets less scrutiny than a quad on a cart in the weather, because the quad is where people actually get hurt. Temporary does not mean exempt. It means the highest-risk wiring on the site, governed by OSHA 1926 Subpart K and NEC Article 590.
The temp service, the pole, and the distribution panel
Temp power starts at a source. On most jobs that is a temporary utility service the power company sets, landed on a temp pole or service rack the electrician builds to the utility's spec. Where there is no utility yet, the source is a generator. Either way the system downstream is the same idea: a main disconnect, a distribution panel, branch breakers, and the feeders and receptacles that fan out from there.
The temp pole carries the meter, the main disconnect, and usually the first bank of GFCI-protected receptacles. It has to be built and braced to stand up to weather and to the utility's requirements, which the utility publishes and the AHJ enforces. The main disconnect is the one that kills the whole temp system. Everyone on the crew should know where it is before they need it.
From the main, temp feeders run to distribution panels and spider boxes spread across the site so the cords from any work area stay short. The branch breakers in those panels are commonly GFCI breakers, which is one clean way to satisfy the receptacle GFCI rule at the panel instead of at every device. The whole assembly is built to NEC Article 590, which covers how temporary feeders, panels, receptacles, and lighting go together, with the utility spec and the AHJ controlling the service end.
Does construction temporary power need GFCI?
Yes. GFCI protection is the headline rule of construction temp power, and it is not optional. OSHA 1926.404(b)(1) requires that all 120 V, single-phase, 15- and 20-ampere receptacle outlets that are not part of the permanent wiring and are in use by employees have approved GFCI protection for personnel, or that the employer run an assured equipment grounding conductor program instead. The NEC says the same thing from the installation side. NEC 590.6(A) requires GFCI protection for personnel on all 125 V, single-phase, 15-, 20-, and 30-ampere receptacle outlets that are not part of the permanent wiring and are in use by personnel.
The two are not worded identically, and the difference trips people. OSHA's GFCI line is written around 120 V, 15 and 20 A, because higher-voltage GFCIs were not available when the rule was written, and OSHA has since said using a GFCI on a higher-voltage circuit is acceptable. The NEC reaches 125 V and adds the 30 A receptacle. Where both apply, you meet the stricter reading, which is GFCI on the 15, 20, and 30 A personnel receptacles.
The phrase in use by personnel is the one crews argue with. A receptacle does not get a pass because it is temporary, or because nobody is standing at it this minute. If it is in service and people use it, it is covered. GFCI catches the ground fault the equipment ground might not clear fast enough, and on a wet site that fault path is often a person.
GFCI as the default, the assured grounding program as the alternative
GFCI is the norm and the assured equipment grounding conductor program is the exception. OSHA gives you the two paths as equals on paper, but in the field GFCI wins almost every time, because it is automatic and protects against an actual fault, while the assured grounding program only proves the ground path was intact the last time someone tested it. For ordinary 120 V hand tools and site receptacles, GFCI is simpler and safer to administer.
The assured grounding program earns its place where GFCIs nuisance-trip: long temp feeders that build up capacitive leakage, and high-inrush loads like welders, big pumps, and concrete saws. On those, a GFCI can trip with nothing actually wrong, and a tripped tool on a deadline is how crews start defeating protection. The program is the path that keeps the ground verified without the trips, as long as somebody actually runs it.
Running the program is real work: a written plan, a designated competent person, two tests on every cord, tool, and receptacle, a test schedule, color-code tagging, and records an inspector can read. The full procedure, the two tests, the intervals, and the color system are covered in the AEGCP field guide and not repeated here. The one thing you cannot do is run neither. No GFCIs and no written program is not a gray area, it is a site with no protection method at all.
What is a spider box?
A spider box is a portable temporary power distribution box that takes one feeder input and splits it to several GFCI-protected receptacles, so a single run from a panel can feed a whole work area. The name comes from the cord legs that fan out of it. It is also called a temporary power distribution box or a power distribution box.
The point of a spider box is to push protected, listed distribution out to where the work is, which keeps the cords short and puts the GFCI right at the receptacle. A listed temporary power product, built for the abuse, beats a homemade box of devices screwed to a scrap of plywood, which is what crews build when the budget says no and which is exactly the kind of thing an inspector and a fire marshal both flag. The box should be listed for the use, with GFCI on the receptacles, a feed-through so boxes can chain, and a housing that takes a drop and a soaking.
Set them up off the ground and out of standing water, feed them from a panel or another listed box, and do not overload the input. A spider box is distribution, not a license to ignore the load on the feeder behind it.
Can you use a damaged extension cord?
No. A damaged extension cord comes out of service. OSHA 1926.405 requires flexible cords on a construction site to be protected from damage, and a cord with a cut or abraded jacket, exposed conductors, cracked or melted insulation, or a bent or missing ground pin is a cord that is out, not a cord you wrap in tape and keep using. The daily look before use is what catches it, and the person grabbing the cord is the one who has to look.
The cord itself has to be the right kind. Extension cords used with portable tools have to be three-wire and rated for hard or extra-hard usage, marked with a type like SOOW or SJTW along the jacket. The cheap two-wire household cord has no place on a jobsite. Strain relief has to be provided where the cord meets a plug or fitting so a pull lands on the clamp and not on the terminal screws, because a cord yanked out by the cord instead of the plug loosens the conductors right where they land.
Cords are used in continuous lengths without splices or taps. There is a narrow exception for hard-service cord No. 12 or larger, spliced so the splice keeps the insulation and jacket properties of the original, but the taped-together field splice does not qualify. Keep cords off the wet ground and out of standing water, not run through doorways and windows where the edge pinches them, and not where a lift or a loaded cart rolls over them. A cord that gets run over goes out of service and gets checked before it goes back, even if the jacket looks fine, because the strands inside can be broken where you cannot see.
Receptacles, boxes, and covers
Every box, fitting, and receptacle in the temp system has to be listed and intact. That means covers on the boxes, faceplates on the receptacles, no open knockouts leaving a hole into an energized box, and no devices hanging out of a box by their conductors. The open knockout is the small thing that fails an inspection fast, because it is a finger or a screwdriver away from a live part and it lets water and dust straight in.
The receptacles carry the GFCI requirement, and you can land that protection three ways: a GFCI receptacle, a GFCI breaker feeding the circuit, or a listed GFCI cord set or device identified for portable use. Any of those satisfies the rule as long as the receptacles in use are actually protected. What does not satisfy it is a standard receptacle on a temp circuit with the GFCI pulled out because it kept tripping.
Boxes get mounted, not left loose on the ground. A receptacle assembly sitting in the dirt is a wet-location problem and a damage problem at once. Mount it, support it, and keep the open face of every box closed.
Temporary lighting: guards, height, and support
Temporary lighting has its own rules because the failure mode is a person grabbing a hot, broken bulb or a live socket in a dark stairwell. OSHA 1926.405 requires lamps for general illumination to be protected from accidental contact and breakage, which means a guard, a cage, or a recessed or enclosed lamp on every string light and temp fixture. A bare bulb on a string with no guard is a citation and a cut hand waiting to happen.
Common practice is to run temp lighting on its own circuit, separate from the receptacle circuits feeding tools, so a tool tripping a breaker does not drop the lights and leave people in the dark on a stair or a ramp. The string and fixtures have to be listed for the use, and the flexible cord feeding portable lights has to be hard or extra-hard usage like any other site cord.
Two things crews get wrong. First, height: keep the lights up and out of the path of traffic and material, commonly mounted around 7 ft above the working surface where the layout allows, so nobody walks into them. Second, support: temp lights are not suspended by their own electric cord unless the cord and fixture are specifically designed for it. The lamp guard is not optional and the cord is not a support wire.
Voltage drop on long temp feeders and cords
Temp power runs long, and long runs starve tools. The feeder crossing a slab the size of a parking lot and the 150 ft of extension cord daisy-chained to reach the far corner both drop voltage, and the tool at the end sees less than its nameplate. A saw that bogs down, a compressor that nuisance-trips, a charger that runs slow: on a long temp run, that is often voltage drop, not a bad tool.
The cord gauge is the lever. A long run on an undersized cord is the classic temp-power mistake, because the crew grabs whatever 16-gauge cord is in the gang box and chains three of them. Match the gauge to the length and the load. For a real run feeding a real tool, a 12-gauge or 10-gauge cord holds the voltage where a 16-gauge chain will not. Push the distribution out with spider boxes so the cord legs stay short, instead of solving distance with cord length.
The full method, the formula, the resistance values, and how to size for the drop are in the voltage drop field guide. On temp power the short version is this: distance and load drive the gauge, daisy-chaining cords is how you get the distance wrong, and the tool at the far end is the one that tells you.
Grounding and bonding the temp system
The temp system has to be grounded and bonded like any electrical installation, under NEC Article 250 and the temporary provisions of Article 590. Every cord-and-plug tool that needs grounding keeps its equipment grounding conductor, every box and panel is bonded, and the system has a grounding electrode and a grounding-electrode path at the source. The ground is the path that carries fault current back to trip the breaker, and on temp power it is also the path the GFCI watches.
The equipment ground and the GFCI work together, not instead of each other. The GFCI catches the fault that gets onto the ground path or onto a person before the breaker would. But a missing or open ground, a cut ground pin, a backed-out crimp, defeats the slower protection and leaves the frame of a tool able to sit energized. That is why the assured grounding program, where it is used instead of GFCI, is built entirely around testing that ground path.
Bonding ties the metal together so there is no voltage difference between two things a person can touch at once. On a temp service that means the neutral-to-ground bond is made at the right single point, and made once. Two bonds, or a bond in the wrong place, puts neutral current on the ground path and on the equipment, which is its own hazard and a common find on a sloppy temp setup.
Does a generator for temp power need GFCI and bonding?
Yes, and the bonding answer depends on how the generator is connected. A portable or towable generator used for temp power feeds the same kind of personnel receptacles as any other source, so the GFCI-or-assured-grounding requirement applies regardless of where the power comes from. Many construction-rated gensets ship with GFCI-protected receptacles for exactly this reason. If a generator's receptacles are not GFCI, the protection has to be added downstream.
The neutral bonding turns on the separately derived question. When the generator only supplies cord-and-plug equipment through receptacles mounted on the generator itself, OSHA and the NEC treat it as not a separately derived system, the frame can serve as the grounding means, and the neutral is bonded to the frame at the generator. When the generator instead feeds a transfer switch, a panel, or conductors that originate in another system, it becomes a separately derived system and the neutral-to-ground bond and grounding electrode are handled at that point, not doubled up.
Getting this wrong shows up two ways. A floating neutral on a generator that should have a bonded one can keep GFCIs from working right and leave fault current without a clean path. A double bond, generator bonded and the panel bonded too, puts neutral current on the ground. The rule of thumb: a stand-alone generator feeding its own receptacles is bonded at the generator, and a generator feeding a building or a panel is bonded once at the system. Confirm the configuration against the equipment listing and 1926.404.
Wet and weather protection
Temp power lives in the weather, so the receptacles, boxes, and equipment have to be rated for it. Receptacles in a wet location need an enclosure that stays weatherproof with a cord plugged in, which is the while-in-use cover, the bubble cover, and in many cases a box hood listed for extra-duty use. The plain snap cover that only closes when nothing is plugged in does not cut it where a cord stays connected in the rain.
Keep the boxes and spider boxes up off the ground and out of standing water. A receptacle or a distribution box sitting in a puddle is the textbook shock setup, and rain plus a worn cord plus a person on a wet slab is the chain GFCI exists to break. Listed equipment and a cover that works with a cord in it are what keep the water out of the part that bites.
The GFCI requirement and the wet-location requirement reinforce each other. Wet locations are exactly where ground-fault protection matters most, and the NEC ties GFCI to damp and wet receptacle locations on top of the blanket temp-power rule. On temp power you treat the whole site as a wet location until proven otherwise, because most of the time it is.
What does an OSHA inspector check on temp power?
An inspector starts with the cords and the GFCIs, because that is where people get hurt. They look for GFCI protection on the receptacles in use, damaged or spliced cords still in service, missing ground pins, open knockouts and missing covers, and lighting without guards. They check whether the site is on GFCI or running a documented assured grounding program, and if it is the program, they ask for the written plan, the named competent person, and the test records on site.
The daily piece is on the crew, not the inspector. Before use, somebody looks at the cord and the tool: jacket, insulation, ground pin, strain relief, plug condition. A GFCI gets its test button pushed to confirm it trips and resets. Damaged items come out and get tagged, not set back in the gang box for the next person. None of this is exotic, and all of it is what fails when nobody owns it.
If the site runs an assured grounding program instead of GFCI, the periodic testing and the color-code tagging carry the documentation, and the test record has to match what is actually in service. That whole program, the intervals, the two tests, and the records an inspector asks for, is detailed in the AEGCP field guide.
Sizing the temp service for the load
Size the temp service for what the job actually plugs in, not for a round number that felt big enough. The load on a temp system is lumpier than a finished building: a tower crane or a material hoist, a few welders, the field trailers with their own heat and AC, concrete vibrators and pumps, and the trades' tools all going at once during the push. Add it up honestly, with the continuous loads counted at 125 percent, and size the service and feeders to carry it.
The loads that bust a temp service are the motors and the welders. A welder pulls hard and intermittently, a hoist motor pulls a big inrush every time it starts, and several of them on an undersized service drag the voltage down for everyone. The trailers are a steady base load people forget because they are always on. Underbuild the service and the symptom is breakers tripping, tools bogging, and the crew running cords to whatever circuit still has room, which is how the system ends up overloaded and abused.
Build in headroom. The temp load grows as the trades stack up through the schedule, and the service that fit the foundation phase is undersized by the time the building is full of finishers. It is cheaper to set a bigger temp service once than to keep adding to a system that was sized for the early light load.
Cords underfoot, overhead lines, and the dig
The cords themselves are a hazard before they ever fault. A cord across a walkway is a trip, a cord across a roadway gets crushed, and a cord through a puddle is a shock path. Route them overhead where you can, along walls and out of traffic where you cannot, and ramp or bridge the ones that have to cross where people and equipment move. Keeping cords up and out of the way is housekeeping and electrical safety at the same time.
Overhead power lines are the killer on the list. Cranes, booms, dump beds, scaffold, and material being hoisted all reach into energized lines, and contact with an overhead line is one of the most common electrocution causes on construction sites. Maintain the clearance, mark the lines, and treat every overhead conductor as live. The clearances are set by OSHA and the utility by voltage, so confirm the distance for the line you are working near and post it.
Underground is the other one. Before any dig, locate the existing utilities, because the temp feeders you bury and the permanent services already in the ground are both there to be hit. Call the locate, confirm it, and hand-dig where the locate says something is close. A backhoe through a live feeder is a fault, a fire, and a person in the trench all at once.
The transition to permanent power
At some point the building's permanent service energizes and the temp system comes out, and that handoff is its own small project. The permanent service gets commissioned and accepted, the loads move over circuit by circuit, and the temp feeders, panels, and cords get pulled rather than left buried in the finished building. Temp wiring left in place inside a finished structure is a code and a fire problem, and it is the kind of thing that surfaces years later in a remodel.
Plan the overlap. The site still needs power while the permanent service comes up, so the temp system usually runs alongside the new one for a stretch, and you stage the transfer so no work area goes dark and no load gets double-fed from both systems. Keep the temp system maintained right up to the day it comes out, because the last weeks of a job, with finishers everywhere and the schedule tight, are when temp power gets the most use and the least attention.
NEC Article 590 governs the temporary installation for the duration of construction. The 90-day limit people quote applies to certain other temporary uses, not to construction power, which is permitted for the period of the work. The point is that temporary has an end, and the plan should include taking the system out, not just putting it in.
Temp power on a data center or large build
On a large data center or industrial build, the temporary power system is a major installation in its own right. Temp feeders run hundreds of feet across slabs the size of several football fields, dozens of distribution panels and spider boxes feed hundreds of tools across trades the electrical contractor does not employ, and the loads include welders, core drills, and large pumps that trip GFCIs on inrush. The scale changes how you run it.
This is the mix where the assured equipment grounding conductor program often shows up alongside GFCI: GFCI on the general-use 120 V receptacles where it works, and a written program covering the high-draw and long-feeder equipment where nuisance trips would otherwise get protection defeated. The long runs also make voltage drop a real design problem, not an afterthought, so the temp feeders get sized for the drop over the distance the same way a permanent feeder would.
The other thing scale brings is logistics. Tracking thousands of cord ends, keeping spider boxes fed and off the ground, and finding the one overdue cord among thousands is a coordination job, which is where a tracked record and a clear marking system stop being paperwork and start being the only way to keep the site safe. Tools like Anvilfield's FieldOS keep that record and the daily checks attached to the actual equipment instead of a clipboard that walks off.
Lockout, tagout, and working it safe
Temp power gets worked on live more than it should, because it is temporary and the crew is in a hurry. It still kills you. Before working on a temp circuit, panel, or feeder, de-energize it, lock and tag the disconnect, and verify it dead with a meter you just proved on a known source. The temporary label does not change the physics, and 277 or 480 V on a temp feeder is exactly as lethal as it is anywhere else.
The energized-work exposure on temp power is the routine stuff: clearing a tripped panel, swapping a device, tracing a dead leg. Treat the temp panel like any other panel. Know where the main disconnect is, know what feeds what, and do not assume a temp circuit is dead because the tool on it is off. Someone else can re-energize a circuit you are standing in if it is not locked out.
GFCI is shock protection for the people using the tools, not a substitute for de-energizing when you work on the wiring. A GFCI protects against a ground fault. It does nothing for the line-to-line contact you make reaching into a live panel. Lock it out, verify it dead, then work it.
What to document
The record on temp power is what proves the daily checks and the periodic tests actually happen, and it is what an inspector asks for on a site running an assured grounding program. Capture the circuit or device, whether GFCI protection is present and tested, the cord condition from the last look, the inspection or test date, and who did it. The point is to tie each piece of the system to a check and a date so an overdue or failed item gets found before it fails on somebody.
If the site is on GFCI, the documentation is lighter but still real: the GFCI test results and the daily cord and tool checks. If the site runs the assured grounding program, the full written plan, the test records, and the color-code legend are the document set, covered in the AEGCP field guide. Keep whatever you keep on site, where the foreman and the compliance officer can both reach it.
| Field to record | Why it matters |
|---|---|
| Circuit or device ID | Ties the check to a specific receptacle, box, cord, or tool |
| GFCI protection present and tested | The headline requirement, confirmed at the device or breaker |
| Cord and device condition | Jacket, insulation, ground pin, strain relief from the daily look |
| Inspection or test date | Proves the daily check and any periodic test happened |
| Tester or inspector | Ties the result to a person |
| Result and action | Pass stays in service, fail is tagged and pulled |
Common mistakes
- Standard receptacles in use with no GFCI, or a GFCI pulled out because it kept tripping.
- Damaged, taped, or field-spliced extension cords left in service.
- Cords run through standing water, across roadways, or pinched in doorways and windows.
- Temp string lights with no guards on the bulbs, or lights suspended by their own cord.
- Long runs on undersized, daisy-chained cords, so the tool at the end runs low on voltage.
- A portable generator with the neutral bonded wrong for how it is connected, or no GFCI on its receptacles.
- No GFCI and no written assured grounding program either, treating temp power as exempt.
- No daily inspection, so damaged cords and dead GFCIs stay in the gang box.
Field checklist
Want this checklist to run itself on every job — with photo proof and a signed record crews can hand the customer? That's FieldOS.
Standards and references
OSHA 1926 Subpart K is the construction electrical standard, and the temp-power core sits at 1926.404(b)(1), which sets the GFCI-or-assured-grounding requirement, with the GFCI option at (b)(1)(ii) and the assured grounding program at (b)(1)(iii). Flexible cords, extension cords, and temporary lighting are covered at 1926.405, including the hard-usage cord rating, strain relief, the no-splice rule, and lamp guarding. The competent-person definition the grounding program relies on is at 1926.32(f). Confirm whether your jurisdiction runs federal OSHA or a state plan, since state plans can be at least as strict.
The installation itself is built to the NEC, NFPA 70. Article 590 covers temporary installations, including temporary feeders, panels, receptacles, and lighting, and 590.6 carries the GFCI provisions for temporary wiring on 125 V, 15, 20, and 30 A personnel receptacles. Article 250 governs grounding and bonding, and the conductor and overcurrent rules of the general articles still apply to the temp feeders and branch circuits. The exact section numbers shift between code cycles, so confirm them against the edition the jurisdiction has adopted and any local amendments before citing them on a submittal.
NECA temporary power practices give installation guidance for how the system is actually built and maintained, and the utility's temporary-service specification governs the service end. Equipment listings and manufacturer instructions govern the spider boxes, cords, generators, and lights themselves. Cite the rule that controls the point: OSHA for personnel protection, the NEC for how the temporary installation is built, and the adopted edition and the AHJ control where they apply.
Units, terms, and abbreviations
Temp power goes by a handful of names and ratings across specs, catalogs, and toolbox talks, so the same item reads differently from one document to the next.
Temporary power is shortened to temp power. A ground-fault circuit interrupter is a GFCI, sometimes written GFI on older gear. A spider box is also called a temporary power distribution box or a power distribution box. Cord ratings show up as type letters on the jacket, like SOOW, SJTW, or S, with the hard and extra-hard usage rating marked along the length. Conductor size is AWG, and the lower the number the bigger the wire, so a 10-gauge cord is heavier than a 16. Service and feeder capacity is in amps, and the loads people add up are in amps or kVA on the nameplates.
- Temp power
- Temporary power, the electrical system that runs a construction site before the permanent service is energized
- GFCI / GFI
- Ground-fault circuit interrupter, the protection that trips on fault leakage current to protect personnel
- AEGCP
- Assured equipment grounding conductor program, the written OSHA alternative to GFCI on temporary power
- Spider box
- A portable, listed temporary power distribution box that splits one feeder into several GFCI-protected receptacles
- Hard / extra-hard usage
- The flexible-cord ratings required for jobsite cords, marked on the jacket, like SOOW or SJTW
- While-in-use cover
- A weatherproof receptacle cover, the bubble cover, that stays weatherproof with a cord plugged in
- Separately derived system
- A power source like a generator that feeds a panel or transfer switch, which changes where the neutral is bonded
FAQ
Does construction temporary power need GFCI?
Yes. OSHA 1926.404(b)(1) and NEC 590.6 require GFCI protection on the temporary receptacles personnel use during construction, the 120 V to 125 V, 15, 20, and 30 A outlets that are not part of the permanent wiring. The only alternative OSHA allows is a written assured equipment grounding conductor program. You run one or the other, never neither.
What is a spider box?
A spider box is a portable temporary power distribution box that takes one feeder input and splits it to several GFCI-protected receptacles, with cord legs fanning out to nearby tools. Use a listed temporary power product, set it off the ground and out of water, feed it from a panel, and do not overload the input.
Can you use a damaged extension cord on a jobsite?
No. A cord with a cut jacket, exposed conductors, cracked insulation, or a bent or missing ground pin comes out of service, not wrapped in tape. OSHA 1926.405 requires cords protected from damage, three-wire and rated for hard or extra-hard usage, with strain relief and no field splices. Check every cord before use.
What is an assured equipment grounding conductor program?
It is the written OSHA alternative to GFCI on temporary power. A competent person tests every cord, receptacle, and tool for ground continuity and correct termination, on a schedule, and records it with color-code tagging. Crews use it where GFCIs nuisance-trip on long feeders and high-inrush tools. The AEGCP field guide covers the full procedure.
Does a generator need GFCI for temporary power?
Yes. A generator feeding personnel receptacles carries the same GFCI-or-assured-grounding requirement as any temp source, and many construction gensets ship with GFCI receptacles. The neutral bonding depends on connection: bonded at the frame when it only feeds its own receptacles, bonded once at the system when it feeds a panel or transfer switch.
How long can temporary power stay on a construction site?
Construction temporary power is permitted under NEC Article 590 for the duration of the construction, remodeling, maintenance, or demolition work, then it comes out. The 90-day limit often quoted applies to certain other temporary uses, not to construction power. Confirm the adopted code edition and any local amendments with the AHJ.
Do temporary string lights need guards?
Yes. OSHA 1926.405 requires lamps for general illumination protected from accidental contact and breakage, so every temp string light and fixture needs a guard, cage, or enclosed lamp. Run lighting on its own circuit so a tripped tool does not kill the lights, and do not suspend lights by their own cord.
Why does my tool run weak on a long extension cord?
That is usually voltage drop. A long run, especially daisy-chained on undersized 16-gauge cord, drops voltage so the tool at the end sees less than its nameplate and bogs down or nuisance-trips. Use a heavier 12 or 10-gauge cord sized to the length and load, and push distribution out with spider boxes.
Can I leave temporary wiring in the finished building?
No. Temporary feeders, panels, and cords come out when the permanent service takes over. Temp wiring left in a finished structure is a code and fire problem that surfaces in a later remodel. Plan the transition so loads move to the permanent service circuit by circuit and the temp system is removed, not abandoned in place.
People also ask
Codes cited in this guide
This guide is written and reviewed against the published standards below. Always confirm the current adopted edition with the authority having jurisdiction.