Transformer lead times on EV charging projects
Assume the transformer sets your completion date, and get a dated lead time in writing from the utility before you freeze the design. It is the single most common reason a finished charging depot sits dark. We publish no national month count, because the only figure that matters is the one your utility quotes for your specific unit on a specific date — and that figure moves, which is exactly why a number printed on a web page is worth less than a dated line in an email.
Updated 2026-08-20
Ask for it in writing, and ask early
The phrasing that gets a useful answer names the unit, the date and the escalation path: for a service of approximately this size at this address, what is the current quoted lead time for the transformer, as of today? Is that unit one you stock, or is it built to order? If the date moves, how and when will we be told?Three things come back from that. A number, a date the number was true, and whether you are waiting on a warehouse or a factory. Those are different waits and they deserve different contingency.Then re-ask at design freeze and again at order placement. A lead time quoted six months ago is not a lead time, it is a memory, and a project plan built on it will discover the difference at the worst possible moment.Keep the answers. A dated written lead time is what lets you set a defensible vehicle-delivery date, and it is what protects you internally when the date moves for reasons that are not yours.
Utility-owned or customer-owned changes almost everything
This is decided by the utility's standard practice for a service of your size at your voltage, not by preference.Utility-owned generally means the utility procures, owns, maintains and replaces it. It may come out of their stock, which can be dramatically faster, and it may be covered wholly or partly by make-ready. You get less control over the schedule and more protection from it.Customer-owned generally means you specify and buy it, you own the lead time risk directly, and you own the failure risk for its whole life. You get more control over the specification and the order date, and you inherit a maintenance obligation and a spare-parts problem that nobody mentions at proposal stage.
The shape of the delay, and why it takes that shape
The specification is kVA rating, primary and secondary voltage, impedance, pad-mount or vault, radial or loop feed, plus a list of the utility's own construction standards. Change any of those and you are ordering a different product.That is the mechanism behind the whole problem. Standard units at standard ratings are the ones utilities keep and the ones manufacturers build in volume. Non-standard units are made to order, and made to order means a queue.So the difference between a fast project and a slow one is usually a design decision made months earlier by somebody who did not know the utility's stock list existed.Lead times also move with wider demand for grid equipment, which is not something a fleet project can influence. Treat the figure as volatile: get it dated, re-confirm it, and build contingency around the date rather than trusting it.
How to end up with a shorter wait
Ask which pad-mount ratings the utility stocks at your service voltage and try to land the project on one of them. A depot sized at 275 kW that fits a stocked standard unit will be energised long before one sized at 310 kW that does not.Load management routinely cuts the required capacity by half or more on an overnight depot, and halving the capacity is the most reliable way to drop into a smaller, more commonly stocked unit.A depot that fits inside existing capacity skips this entire phase, and that is worth real design effort — it is often the difference between energising this year and next.Phase the energisation. If the transformer is the constraint, energise a subset of ports on existing capacity and bring the rest online when the unit lands. The trench and conduit are already in; only the switchgear and the ports wait.Order the day the design is fixed, not the day the permit issues. On customer-owned equipment those can be months apart, and it is calendar you never get back.
What to do while you wait, and what to do if the date moves
The civil work, the conduit, the pads, the permit, the charger procurement and the network configuration can all proceed against a known energisation date, and none of them should be waiting on a delivery.Many programs disqualify work begun before their pre-approval date, and a transformer wait is exactly the kind of dead time that tempts a team into starting the trench early.If the date moves, protect two things: the vehicle delivery schedule and the make-ready approval window. Approvals frequently carry an expiry — a period within which the work must be completed — and a slipped transformer can push you past it. Tell the program administrator as soon as you know, in writing, and ask what extension process exists.Tell whoever ordered the vehicles at the same time. A transformer slipping by a quarter is a manageable problem. A transformer slipping by a quarter that nobody mentioned until the vans arrived is not.
How long is the lead time for a transformer on an EV charging project?
Ask your utility for a dated figure for your specific unit, because that is the only version worth planning against. Lead times differ by rating, by specification and by whether the unit is stocked or built to order, and they move over time. Any national number you find published will be stale and may be wrong by a wide margin in either direction.
Can I avoid needing a new transformer?
Sometimes, and it is worth serious design effort. Size the depot to the managed peak rather than the sum of charger nameplates, which on an overnight fleet often halves the requirement, then check that figure against spare capacity on the existing service using twelve months of interval data from the utility. Depots that fit the existing service skip the longest phase of the project.
Who buys the transformer, me or the utility?
It depends on your utility's standard practice for a service of your size and voltage. Utility-owned means they procure, maintain and replace it, often from stock and often within make-ready scope. Customer-owned means you specify, buy, maintain and eventually replace it. Ask which applies before you budget.
Should I order the transformer before the permit is issued?
On customer-owned equipment, order as soon as the design is fixed and the utility has confirmed the specification. Waiting for permit issue adds that review time onto a lead time that is already the longest item on the project. Check first that ordering early does not conflict with a make-ready program rule about work commencing before approval.
What happens if the transformer arrives after my make-ready approval expires?
That depends on the program, and it is a real risk rather than a hypothetical one. Approvals commonly carry a completion window. Notify the administrator in writing as soon as the delay is known and ask about the extension process — programs generally have one, and using it is much easier than reapplying.
- US DOE Alternative Fuels Data Center, utility and private incentives — locating the serving utility and its make-ready program, which determines transformer ownership and cost responsibility on many projects
- GreenLancer, Guide to commercial EV charging stations — electrical infrastructure as a share of commercial charging project cost, of which transformer and service work is the largest part