What to Know Before Wiring a New Shop or Garage in Bonner County

August 16, 2026 · Family-owned electricians in North Idaho

Public domain, via Wikimedia Commons

This is for anyone in Bonner or Kootenai County about to wire a new detached shop, garage, or outbuilding, whether it is a weekend project space, a full workshop, or a building that will run a small business someday. The single most important decision is how much electrical load that building needs to carry, not just today but five or ten years from now. Get that number wrong and everything downstream, panel size, wire gauge, permit scope, cost, gets harder or more expensive to fix later.

Decide this first

Before you talk to an electrician or pull a permit, decide what the shop actually needs to run, at the same time, on the worst day. Not what it might run occasionally. What it runs together. A shop with a welder, a compressor, a couple of 240V tools, and lighting draws very differently than a garage with a car lift and a mini split. This number, your calculated load in amps, decides whether you need a 100A subpanel or a 200A service, whether your existing house panel has room to feed it, and whether you are looking at a simple feeder run or a full new service with its own meter. Everything else in this post follows from that decision.

What to look for

Feeder size and panel capacity

Most detached shops and garages in this area end up fed by either a 60A, 100A, or 200A subpanel, depending on planned equipment. A small hobby garage with lighting, outlets, and a compressor can often work with 60 to 100 amps. A working shop with welding equipment, air tools, a kiln, or a future EV charger usually justifies 100 to 200 amps. It costs far less to size the feeder correctly the first time than to trench a yard and repour a slab to upgrade later. If there is any real chance you will add equipment in the next five to ten years, size up now. The incremental cost of a bigger wire and panel today is a fraction of the cost of doing it twice.

Subpanel vs. separate service

Most detached buildings on the same property as the house are fed as a subpanel off the main service, which keeps things simpler and usually cheaper. But if the shop is far from the house, has commercial use, or the main panel has no spare capacity, a separate service with its own meter may make more sense. This decision affects utility coordination with your power provider, trenching distance, and permit paperwork. It is worth discussing both options with whoever is doing the load calculation rather than assuming a subpanel is automatically the right call.

Permits and inspection through Bonner County

Electrical work on a new structure in Idaho requires a permit and inspection through the state electrical program, and Bonner County requires a building permit for most new detached structures over a certain size, plus separate mechanical and electrical permits as applicable. Requirements vary by structure size, use, and whether the building has plumbing, so check current thresholds with Bonner County Building and Planning before assuming anything is exempt. Skipping the permit does not just risk a fine. It risks an uninspected panel and feeder buried under a slab or behind drywall, which becomes expensive to prove safe later, especially at resale.

Equipment-specific circuits

Welders, air compressors, table saws, dust collectors, EV chargers, and mini-split heat pumps each have their own voltage, amperage, and sometimes dedicated circuit requirements. A 240V welder outlet is not the same as a 240V dryer outlet, and treating them interchangeably is a common and costly mistake. List every piece of equipment you expect to run, including anything you are likely to buy in the next few years, before final circuit planning. This list is the actual input for the load calculation, more useful than square footage alone.

What to ignore

Smart panels with app monitoring and remote breaker control look appealing in marketing materials, but for a shop or garage they rarely solve a real problem most owners have. The added cost is better spent on proper feeder sizing or an extra 240V circuit for equipment you will actually use. Similarly, oversizing a panel to 400A “just in case” without any real plan for that capacity adds cost without benefit. Panel brand name is largely irrelevant as long as it is a reputable manufacturer carried by supply houses in this region, since parts availability and warranty support matter more than the label. Decorative exterior disconnect covers, upgraded panel door finishes, and similar cosmetic options do not affect function and are not worth paying extra for in a work building.

Common mistakes

The most frequent mistake is undersizing the feeder to save money upfront, then discovering two or three years later that the shop needs 240V for a new compressor or welder and the existing wire cannot support it. At that point, upgrading often means trenching an already landscaped yard or opening a finished wall, which costs more than doing it right the first time would have.

Another common issue is skipping the permit and inspection process on a detached building, either to save time or because someone assumed a garage did not need one. Unpermitted electrical work can complicate a home sale, cause problems with insurance claims after a fire or damage, and in some cases require the work to be opened up and re-inspected before it can be signed off after the fact. It is far less disruptive to get the permit before construction than to retrofit compliance afterward.

A third mistake specific to detached structures is inadequate grounding and bonding at the subpanel. A detached building fed by a subpanel needs its own grounding electrode system, and the neutral and ground must be handled correctly, separated at the subpanel rather than bonded together as they might be at a main panel. This is a code requirement, and getting it wrong creates a real shock hazard, not just a paperwork problem. It is one of the more common errors found during inspection of owner-wired detached buildings.

FAQ

Do I need a permit for a detached garage or shop in Bonner County?

In most cases, yes. Bonner County generally requires a building permit for new detached structures above a certain square footage, and Idaho requires an electrical permit and inspection for any new wiring, regardless of the structure's size. Requirements can shift based on use and size, so confirm current thresholds with Bonner County Building and Planning before you start, rather than relying on secondhand information.

What size electrical service does a typical shop or garage need?

There is no single right answer, it depends on what the building will run. As a rough range, a small hobby garage with basic lighting and outlets might work with 60 to 100 amps. A working shop with welding, air tools, and heating or cooling equipment often needs 100 to 200 amps. The only reliable way to know is a load calculation based on the actual equipment list, not a guess based on square footage.

Can I run power underground to a detached shop instead of overhead?

Yes, underground feeders are common and often preferred for appearance and durability against wind and snow load. They require proper burial depth, conduit in most cases, and careful routing to avoid future digging near the line. Underground runs also cost more upfront due to trenching, so factor that into your budget when comparing options.

Should I plan for an EV charger even if I do not have an EV yet?

If there is a reasonable chance you will own an EV within the life of the building, it is worth adding capacity or at least a conduit stub for a future 240V circuit now. Retrofitting later, especially through a finished wall or slab, costs more than planning for it during initial construction.

If you are still working through the load calculation or deciding between a subpanel and a separate service, it is worth getting an electrician out to look at the site and the equipment list before you finalize plans. Sageland Electric works with homeowners and builders across Bonner and Kootenai counties on exactly this kind of planning, and getting the sizing right at the start saves real money down the road.