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Distribution Panel

A portable distribution panel is the branch-circuit hub of a temporary power system: an enclosure that accepts a feeder from a generator or service, protects outgoing circuits with breakers, and hands power off through receptacles or sub-feed connections. Panels convert one large feed into the many protected circuits a site actually uses.

Models

120/240 V single-phase and 208Y/120 V or 480 V three-phase nominal, configuration dependent

System voltage

Brands

How it works

Feeder power enters through cam-type inlets, hardwired lugs, or a cord, landing on a main breaker or lugs. From there, branch breakers protect individual circuits terminating in receptacles — commonly a mix of straight-blade duplexes for tools and twist-lock or pin-and-sleeve outlets for equipment and sub-feeds. Construction-grade panels build in the protections temporary power demands: GFCI on receptacle circuits, weather-resistant enclosures with covers, and skids, stands, or hanging brackets that keep the panel out of water and traffic.

Types & variants

Portable panelboards: Free-standing or skid-mounted panels distributing a generator or service feed into multiple protected branch circuits.
Temporary power boxes: Compact cord-connected boxes bringing a few protected receptacle circuits to a work area.
Sub-feed and stringer panels: Panels designed to daisy-chain, passing the feeder through while dropping protected circuits along a route.
Hazardous-location distribution: Certified distribution assemblies for classified areas in industrial and plant work.

Key specifications

Specification	Typical range	What it means
System voltage	120/240 V single-phase and 208Y/120 V or 480 V three-phase nominal, configuration dependent	The panel's voltage configuration must match the source and the loads; mixed-voltage panels also host step-down connections.
Branch protection	Thermal-magnetic breakers with GFCI on receptacle circuits	Breakers protect conductors; GFCI protects people — required on construction receptacle circuits.
Feeder inlet	Cam-type inlets, pin-and-sleeve inlets, or lugs, model dependent	Determines how the panel connects to the feeder system and how quickly services assemble.
Enclosure rating	Weather-resistant enclosures on outdoor-rated panels, model dependent	Temporary panels live outdoors in traffic; the enclosure rating must match the exposure.

How the industry sizes it

Panels are sized from the branch-circuit map: enough breaker positions and receptacle types for the tools and equipment served, a main rating that covers the connected demand, and a voltage configuration matching the source. Large sites layer panels — feeder-level panels near the generator sub-feeding smaller boxes at work areas — keeping cord runs short and protection close to the load.

Applications

Distributing generator power into protected tool circuits on construction sites
Temporary building services during renovation and fit-out
Event and production power distribution to vendors and stages
Plant shutdown and turnaround temporary power
Powering trailers, hoists, and fixed equipment through sub-feeds

Safety & operation

Receptacle circuits serving portable tools on construction sites require GFCI protection per OSHA and NEC Article 590.
Keep enclosure covers closed and cord entries fitted; open panels expose energized parts to weather and contact.
Mount panels above standing water and out of vehicle paths, on their skids, stands, or hangers.
Verify grounding and bonding continuity back to the source before energizing; a floating panel ground defeats every downstream protection.
Only qualified persons should open panels or alter breaker configurations.

Standards & certifications

UL · UL 1640: Safety standard for portable power-distribution equipment.
NFPA · NFPA 70 (NEC), Article 590: Temporary installation rules including GFCI requirements for receptacle circuits.
OSHA · 29 CFR 1926.404(b)(1): Ground-fault protection requirements for receptacle outlets on construction sites.

Frequently asked

What distinguishes a portable distribution panel from a building panelboard?

Portable panels are listed for temporary service: weather-resistant enclosures, cord and cam-type connections instead of conduit, built-in GFCI, and formats made to move — skids, handles, and hangers. Building panelboards assume fixed installation in conditioned space.

Does every circuit on a temporary panel need GFCI?

Receptacle circuits serving cord-connected tools on construction sites require GFCI protection under OSHA rules and NEC Article 590. Sub-feeds to other panels and hardwired equipment follow their own protection rules.

How many panels does a site need?

Enough that cords stay short and protection sits near the load — typically a feeder-level panel at the source sub-feeding compact boxes at each active work area, rather than long cord runs from one central panel.