Getting power across the yard

Article 225 generally permits one feeder or one branch circuit to supply a building or structure. That is not a guideline about tidiness. If you run a single 60-amp branch circuit to a charger today, you cannot legally add a second circuit for lights or a workshop receptacle tomorrow. You would have to remove what you installed and replace it with a feeder, which means opening the trench.A feeder to a subpanel costs a few hundred dollars more in materials and an hour or two more in labour. The panel is small, the breakers are ordinary, and the work happens in the same trench on the same day. Against re-excavating a yard in five years, that is not a close call.The single-circuit case does exist. If the structure is genuinely never going to need anything else, if the run is very long and conductor cost dominates, or if the budget is fixed today, one circuit is legal and it works. Make it a deliberate choice rather than a default.

In practice most of these runs are done in PVC at eighteen inches, or in direct-buried cable at twenty-four. PVC costs more in material and time and buys you two things worth having: the conductors are replaceable without digging, and you can put a second empty conduit in the same trench for whatever comes next.The digging is the real expense and it is entirely site-specific, which is why no honest national figure exists for it. Sixty feet of lawn is one price. Sixty feet that crosses a paved driveway, a mature root system, an irrigation zone or a septic field is another price entirely, and the difference is much larger than anything else in the job. Anyone quoting a trench without walking the route has not quoted the trench.Call 811 before anyone breaks ground. It is free, it is the law in every state, and the utility locate is the difference between a normal Tuesday and cutting a gas service.

The disconnect comes from Article 225: a means to disconnect all ungrounded conductors supplying the structure, located at the structure. If you are installing a subpanel with a main breaker, that satisfies it. If you ran a single circuit, you still need one, which is a point people miss because they have correctly worked out that a 48-amp charger needs no EV-specific disconnect.The grounding electrode system is a separate requirement under 250.32. A structure supplied by a feeder needs its own electrode, typically two ground rods, or a concrete-encased electrode where the slab was built for it. The exception is a structure supplied by a single branch circuit that includes an equipment grounding conductor, which needs no electrode.The neutral is where old installations go wrong. Until the 2008 edition, the code allowed the grounded conductor to be re-bonded at a detached structure fed by three wires. That allowance is gone. A modern feeder is four-wire, the neutral bar in the garage panel floats, the equipment ground bonds to the enclosure and to the electrode, and the two are separated. If your garage already has an old three-wire feed and someone tells you it is fine to leave, get a second opinion in writing.

A 60-amp feeder carries a 48-amp charger with nothing left over. A 100-amp feeder carries the charger, a compressor, a welder circuit, lighting and a heater, and it costs a couple of conductor sizes more on the same trench and the same labour. The marginal cost of capacity at install time is small. The cost of capacity later is the whole job again.The same logic applies to the conduit. Two runs of conduit in one trench, one of them empty with a pull string in it, adds very little to the day. That empty conduit is where the network cable, the low-voltage run or the second circuit goes in five years without a shovel.There is a real limit on this: the feeder cannot be larger than your service can support under a load calculation. If the house is on 100 amps and already busy, the garage feeder is sized to what is actually spare, and energy management may be part of the answer. This is the point at which the detached-garage question turns back into the panel-capacity question.

An overhead span to a detached structure is permitted and it has real clearance requirements over ground, over driveways and from windows and roofs. It avoids the trench entirely, which is the whole appeal.What it costs you is everything else. A span across a yard is visible from every window, it is exposed to ice and falling limbs, it constrains where you can park a truck or raise a ladder, and it is the first thing a future buyer notices. Most people who price both end up underground even when overhead is cheaper.Where overhead still wins is a short span between two structures whose walls face each other, or a site where trenching is genuinely impractical: solid rock, a protected root zone, a paved courtyard. Ask for both prices if the route is difficult.

Feeder size and wiring method, stated as a conductor size and a raceway type rather than as an amp figure alone. Trench length, depth and what the route crosses, with restoration of any hard surface named explicitly. The subpanel, its amperage and its spare spaces. The grounding electrode system at the garage. The disconnecting means. The permit, and who is pulling it.Restoration is the line most often left out and most often argued about. Cutting a concrete driveway is one number; putting it back so it does not look cut is another. Get it in writing which of those you are buying.And ask for the charger circuit as its own line inside the garage. Once the feeder and the subpanel are there, the charger is a breaker and ten feet of conduit, and it should be priced like one.