Class 8 Electric Truck Charging Depots

On a light-duty project you pick a site and ask the utility to serve it. On a heavy-duty project that order gets you a two-year answer.A Class 8 battery-electric tractor carries a pack several times the size of a passenger EV's, and a yard full of them is a load closer to a small industrial plant than to a building. Utilities do not add that at an arbitrary address on a normal timeline. What they can often do quickly is serve a site that already sits on or near existing capacity: a former industrial parcel, a site with a retired large motor load, a yard already fed at primary voltage, land near a substation with headroom.So the first call is to the utility's key-account or new-business engineer, with a list of candidate parcels, before a lease is signed on any of them. Ask three things about each: what it can be served at today, what it can be served at after a transformer change, and what would require new primary distribution. The answers will differ by more than the rent does, and the cheapest parcel is routinely the most expensive project.

Charge time is energy divided by power, and for a heavy-duty truck the energy number is large enough that the division settles most arguments on its own. Published pack sizes for Class 8 battery-electric tractors sit in the hundreds of kilowatt-hours and vary by model and by battery option, so use the figure on the spec sheet for the truck you are actually buying rather than a category average.The table below is arithmetic at the stated delivered power. Real sessions run longer, for two reasons that are not the charger's fault: charge rate tapers as the pack fills, and the vehicle's onboard limit, not the dispenser's rating, sets the ceiling for most of the session.

The number that worries a utility planner is connected load: every port at nameplate at the same time. The number that decides your energy bill, and often your real service size, is the average power you need across the dwell window. On a return-to-base yard those two numbers are nowhere near each other, and the gap is the entire design opportunity.Eight trucks each taking on 400 kWh across a ten-hour overnight window is 3,200 kWh at an average of 320 kW. The same eight trucks on 350 kW dispensers, unmanaged, is a 2.8 MW connected load. Same trucks, same energy, roughly nine times the service.An energy management system — the class of equipment NFPA 70 Article 750 covers — is what lets you buy the first number instead of the second, by sequencing and throttling ports against a fixed site limit. It is the single highest-leverage decision on a depot design and it is usually made too late, after the service application has already gone in at nameplate.

For contrast, here is what lands on a service application when nobody proposes load management. It is ports times nameplate, and it is the number that puts a depot into a long interconnection study.This is also why the port count and the dispenser rating should be argued out before the application goes in rather than after. Revising a service request downward is possible; it is just slower than getting it right, because in many territories it means re-entering the queue.

Settled: depot charging at 350 kW and below, on CCS1 or on the J3400 connector, with equipment available from multiple vendors and service contracts behind it. Also settled is the electrical practice. NFPA 70 Article 625 governs electric vehicle power transfer equipment, the circuits are sized as continuous load, and Article 750 covers the energy management systems that let a fixed service carry more ports than its rating would otherwise allow.Not settled: megawatt-class charging. Work on a megawatt connector and its protocols is being carried by CharIN and by SAE under the J3271 program, and the hardware is in demonstration and early deployment rather than in general catalogues with parts availability and a service network behind it. Anyone presenting megawatt charging as a line you can specify, buy and get supported on a normal construction schedule is ahead of the market.That matters for design, not only for procurement. If your duty cycle genuinely needs it — a linehaul relay point rather than a return-to-base yard — say so in the design and build the site so the pads, the conduit and the service headroom are ready when the equipment is. If your duty cycle does not need it, and most return-to-base operations do not, keep it out of the budget.

Per-port DC fast charging at commercial sites is commonly quoted at $50,000 to $200,000 per port, against a full observed range from roughly $18,000 to $350,000 and up, with electrical infrastructure accounting for something like 40 to 60 percent of total project cost. Those figures come from light- and medium-duty commercial work, so treat them as the honest floor for a heavy-duty site rather than the answer to your site.We do not have a defensible per-port figure for megawatt-class equipment and we are not going to invent one. It is not a catalogue item, and the real numbers that exist today sit inside demonstration projects with grant funding attached, which makes them useless as a benchmark for a commercially financed yard.What we can describe is the shape. On a heavy-duty site the chargers stop being the largest line item. Primary service, a transformer and its pad or vault, medium-voltage switchgear, protection and metering, and trenching across a surface engineered for 80,000-pound vehicles will frequently exceed the equipment. Ask every proposal to separate make-ready from equipment, and to say which side of the meter each item sits on — that is what decides who owns it and who maintains it for the next twenty years.

There is no federal tax credit on this equipment. The Section 30C credit terminated for property placed in service after June 30, 2026 under Public Law 119-21, and the business-side per-item credit went with it. If a proposal dated after that shows a federal credit line, it is an error to correct before you sign, not a benefit to bank.What remains is the utility layer and the grant layer. Utility make-ready programs are sponsored per utility, vary in whether they cover customer-side work, and are the reason a per-port figure without a named utility is not worth much. Federal grant funding for charging infrastructure has been administered through the Joint Office of Energy and Transportation and FHWA, and its availability changes with each funding round, so check the current program notice rather than an article about it — including this one.

Installing conduit and panel capacity up front is reported to cut per-port cost by 40 to 60 percent versus retrofitting later, and on a heavy-duty yard the civil work is more expensive and more disruptive than that figure suggests, because you are cutting a surface built to carry loaded tractors.The pattern that works: size the service and the raceway for the eventual truck count, pour the pads, pull the conduit, and populate dispensers as vehicles arrive. Then phase the vehicle deliveries against the utility's energisation date rather than the OEM's build slot. A truck that arrives before its power does is a very expensive parked asset, and it is the most common way these projects go wrong.