Temporary Power on Construction Sites

Temporary power (“temp power”) runs tools, lights, heaters and trailers until permanent wiring is finished. It gets driven over, rained on, buried in drywall dust and moved around every day. That’s why it needs to be installed right, protected and checked often.

• Construction

Parts of a temp power system

• Service pole or temp service: where the utility connects. Set and wired by an electrician, inspected by the local authority.
• Temp panels and distribution boxes: breakers and receptacles mounted on the pole or a stand.
• Feeder cords: heavy-duty cords (often SOOW) running from the panel to spider boxes.
• Spider boxes: portable distribution boxes with several GFCI-protected receptacles.
• String lights and temp lighting for stairwells, interiors and night work.

Requirements

• Temporary wiring must be installed by qualified electricians and meet code (NEC Article 590).
• All 120-volt, 15- and 20-amp receptacles that aren’t part of the permanent wiring must be GFCI protected or covered by an assured equipment grounding conductor program. The electrical code extends GFCI protection to more temporary receptacles. See GFCI Protection.
• Temporary wiring must be removed when the permanent wiring is done or the purpose is complete.
• Temporary lights must have guards over the bulbs, and must not be hung by their cords unless designed for it.
• Boxes, panels and spider boxes must have covers in place and be protected from damage and weather.
• Cords must be protected from damage. They can pass through doorways and other pinch points only if they’re protected.

Protecting cords and feeders

• Run cords overhead on hooks or insulated supports where possible, high enough to clear traffic.
• Use cord ramps or covers where cords cross walkways or drive paths.
• Keep cords out of water, mud and away from sharp edges, rebar and hot surfaces.
• Use cords with the right size (gauge) for the load and length. Undersized cords overheat.

• Don’t staple or nail cords, or tie them with wire.
• Don’t run cords through doorways, windows or holes where they get pinched.
• Don’t bury cords in debris or under material.

Temporary lighting

• Use guards or cages on every bulb so a broken bulb can’t expose the filament or socket.
• Keep stairways, ladders, exits and work areas lit. See Night Work & Lighting.
• Replace broken sockets and missing bulbs. An empty socket is an exposed live part.
• Keep halogen and other hot lights away from combustible material and plastic.

Daily checks

• Spider boxes and temp panels upright, closed and off the ground or out of water
• No damaged cords feeding or leaving the box
• Light strings intact, bulbs guarded, no broken sockets
• GFCIs test and reset properly
• Nothing stacked against or blocking temp panels
• Cords protected where they cross traffic
• Receptacle covers in place

Who can do what

• Anyone: plug in tools, report problems, test GFCIs.
• Only electricians: open temp panels, move feeders, add circuits, repair boxes and lights.

• Don’t open temp panels or reset breakers repeatedly. If something keeps tripping, call the electrician.
• Don’t tap into temp power with homemade cords or adapters.
• Don’t move spider boxes by dragging them by the feeder cord.
• Don’t plug heaters into the same spider box as tools if it trips. Ask for a dedicated circuit.

Last updated: October 1, 2026