The subcontract decides, and when it is silent, the dispute usually starts on the first day of grinding. A general contractor may assume the sub brings its own generator, while the sub may assume site power is provided. Neither assumption is written down, and the crew arrives to find no agreed source of power. Settling this before the bid closes is far cheaper than settling it on site.
Safety obligations add a reason to be explicit. Temporary power on a construction site needs ground-fault protection, as described in OSHA 1926.404, and the contract should say who provides and maintains the gear that delivers it. This page lays out the common arrangements, but your contract terms and legal counsel decide how they apply to your job.
Three common arrangements
Most prep subcontracts follow one of three patterns for power. Each shifts cost and risk between the parties in a different way, so the choice should be deliberate. The table below compares them. It describes tendencies, not rules.
| Arrangement | Who pays for power | Who controls the risk | Watch for |
|---|---|---|---|
| GC supplies power | The GC | The GC, for availability and capacity | Capacity may not match grinding loads |
| Sub supplies power | The sub, priced into the bid | The sub, for sizing and uptime | Bid may leave the cost out by mistake |
| Shared or reimbursed | Split, or sub bills the GC | Both, so terms must be explicit | Disputes over what was agreed |
Why capacity is the hidden issue
The question is rarely whether power exists. Site power is often sized for lights and hand tools, and a grinding and dust collection setup can draw more than a temporary panel was meant to carry. If the GC supplies power, the sub should confirm the capacity, voltage and phase before the bid, not after mobilizing. If the sub supplies it, the sub should size a generator to its own load list, which the sizing guide explains. The common mistakes in sizing a generator for grinders are worth reviewing when building that load list.
The cost of getting this wrong falls on whoever controls the schedule. A crew standing idle because the available power cannot run the grinder and collector together costs time that nobody budgeted. For a view of what an interruption costs a crew, see our page on concrete surface prep power. The page on what a power dip costs on a polished concrete job breaks that cost into lines a crew lead can price.
What to write into the subcontract
The list below covers terms that prevent most power disputes on a prep job. Have counsel review the final language, since the right wording depends on your contract and jurisdiction.
- Who supplies power, and at what voltage, phase and capacity
- Who pays for fuel, if a generator is used
- Who provides distribution and ground-fault protection
- What happens if the supplied power is unavailable or inadequate
- Who is responsible for the unit’s security and maintenance on site
- How the arrangement changes if the schedule extends
Pricing the bid either way
If you are the sub and expect to supply power, put it in the bid as its own line. A rental has size, duration, fuel and delivery components, and the rental pricing guide explains what drives them. If you expect the GC to supply it, state that assumption in the bid so it becomes part of the scope. An unstated assumption is the one most likely to be disputed later.
Talking to Stag before the bid
Stag Power Rentals supplies diesel generators from 20 kW to 2000 kW out of its Dickinson, TX yard. Bring your equipment list and the schedule, and the team can help you price the power line with a unit sized to the load. For the wider picture, see our construction power overview, and when your numbers are ready, request a quote.
Frequently Asked Questions
Who normally supplies power on a concrete prep subcontract?
It varies by contract. Some GCs provide site power, some expect the sub to bring a generator, and some split it. The subcontract should state the arrangement so neither side assumes.
What if the GC’s site power cannot run my grinder and collector?
Confirm the capacity before the bid. If it falls short, the sub can bring a generator, ask the GC to upgrade the supply, or price the difference. Raising it before mobilization is cheaper than raising it on site.
Should the power cost be a separate line in my bid?
Often, yes. A separate line makes the assumption visible and gives the GC a clear choice. Size, duration, fuel and delivery all affect the figure.
Who is responsible for ground-fault protection?
The contract should say. OSHA 1926.404 covers ground-fault protection for temporary receptacles, and the party that provides the distribution gear typically provides it. Confirm the allocation with your safety lead and counsel.
What should I send with a quote request?
Send the equipment list with voltage, phase and amps, the expected duration and shift pattern, and the site location. If the GC will supply part of the power, say so. That lets the rental team price the right unit.