The Complete Guide to Temporary Builders Supply
A trade reference on temporary builders supply — what a builders box contains, single versus three phase, mounting, protection and how to order a pre-wired unit.
What temporary builders supply is
A temporary builders supply — the builders box — provides power to a construction site before the permanent metering and switchboard are installed. It gives the trades GPOs for tools, lighting and site sheds, protected by RCDs and service protection, and it connects to the network through a temporary service. It is the first electrical item on most sites and the last to leave.
EVO Electric supplies temporary builders boxes to Level 2 ASP electricians and builders from our Sydney factory. We do not install them — this guide covers how to specify a box that passes inspection and survives a busy site.
What's inside a builders box
A compliant builders box is a small switchboard purpose-built for site power. The typical contents are consistent across jobs.
- —Main switch to isolate the whole box.
- —RCDs or RCBOs protecting every socket circuit.
- —Multiple GPOs — single and three phase outlets as required.
- —Service fuse (SPD or MPD) and neutral link on the supply side.
- —A weatherproof enclosure with a door that closes over connected leads.
Single phase versus three phase site boxes
The site's tools and equipment decide the phase configuration. Many domestic and small commercial sites run on single phase; larger sites with three-phase plant, cranes or big compressors need a three-phase box.
| Configuration | Typical site | Outlets |
|---|---|---|
| Single phase | House builds, small reno | 10A/15A GPOs |
| Three phase | Commercial, cranes, large plant | 3-phase + single-phase GPOs |
| Combination | Sites with mixed plant | Both, with per-circuit RCD |
Pre-wired beats site-built
A pre-wired builders box arrives with the GPOs, main switch, RCBOs, service fuses and neutral link already assembled and tagged. It removes the most common inspection defects before the box leaves the factory and gets the site powered in a fraction of the time.
- —Factory-assembled and tested — no missing links or mislabelled circuits.
- —Consistent, inspection-ready layout every time.
- —Faster connection means the trades are working sooner.
Mounting and location
Pick the pole or stand position for the whole build, not just the slab pour. Moving a temporary supply mid-build means network involvement and downtime that dwarf the few minutes spent planning the location. The box is usually pole-mounted or on a purpose-built stand, positioned for access and clear of the works.
Bottom lead openings, grey-hose enclosed mains and a box big enough to close over the connected leads keep the installation compliant when the site gets busy and muddy.
Protecting leads and the box on site
A construction site is hard on equipment. Leads get driven over, boxes get knocked and water gets everywhere. Specifying and siting the box to survive this is part of getting it right the first time.
- —Route leads through the bottom of the box, never the top.
- —Use a box with enough internal room to dress and close over leads.
- —Position the box clear of vehicle paths and material stacks.
- —Check the RCDs regularly — site conditions cause nuisance trips and genuine faults alike.
How to order a builders box
Give the wholesaler the site's power picture and the box arrives ready to connect.
- —Single or three phase, and the outlet mix required.
- —Number of GPOs and any special outlets (welder, three-phase plant).
- —Service protection rating — SPD or MPD, 80A or 100A.
- —Mounting method — pole or stand.
- —Whether you want it pre-wired and tagged ready to connect.
Request a quote for a pre-wired builders box and it turns up assembled, tested and ready for the Level 2 to connect — no site build, no surprise defects.
Frequently Asked Questions
What goes inside a temporary builders box?
A main switch, RCDs or RCBOs on every socket circuit, multiple single and three-phase GPOs, a service fuse (SPD or MPD) and neutral link on the supply side, all inside a weatherproof enclosure that can close over connected leads.
Should a builders box be single or three phase?
It depends on the site's plant. House builds and small renovations usually run single phase; commercial sites with cranes, large compressors or three-phase plant need a three-phase box, often with a mix of three-phase and single-phase outlets.
Why choose a pre-wired builders box?
A pre-wired box arrives assembled, tagged and tested, which removes the most common inspection defects and gets the site powered far faster than building the box on site. It also gives a consistent, inspection-ready layout every time.
Where should the temporary supply be positioned?
Choose a position that works for the entire build, not just the slab pour, and keep it clear of vehicle paths and material stacks. Moving a temporary supply mid-build involves network coordination and downtime that far outweigh the planning effort.
Related Products
Temporary Builders Switchboards
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Temporary Builders Supply Solutions
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Temporary Builders Supply for Residential Sites
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Builders Site Power Package
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Temporary builder's supply boxes
Accessories
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Level 2 ASP Contractors
Disconnect/reconnect, metering and overhead service work
Keep Reading
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