Subpanel Installation for Garages, Shops and Additions
Extra circuits where you need them: a detached garage, a finished basement, a shop, an addition or an ADU, fed properly from the main service.
When a subpanel is the right answer
A subpanel is the answer when the main panel has capacity but nowhere left to put a breaker, or when the circuits you need are a long way from the panel. Finishing a basement, wiring a woodshop in a detached garage, adding a mother-in-law suite over the garage in Aurora, or running a well-lit workshop in Erie all point the same direction.
It is the wrong answer when the main service itself is maxed out. Hanging a subpanel off a 100-amp service that is already carrying a heat pump and a car does not create capacity, it just moves the problem. We run the load calculation first and tell you which job you actually have.
- Basement and attic finishes that need eight or ten new circuits
- Detached garages and workshops with 240-volt tools or a welder
- ADUs, casitas and above-garage suites
- Additions where the main panel sits at the far end of the house
- Hot tubs, pool equipment and outbuildings
What is included in a subpanel install
We size the feeder for the load the space will really carry, not the minimum that passes. That means the correct conductor size, a properly sized feeder breaker at the main panel, conduit rated for its environment, and, for a detached structure, a separate grounding electrode with the neutral and ground kept apart at the subpanel.
For detached buildings the feed usually goes underground. We handle the trench, the conduit, the backfill and the restoration, and we tell you up front what the yard will look like when we leave.
- Correctly sized feeder conductors and overcurrent protection
- Trenching, conduit and burial depth to code for detached runs
- Ground rod at the structure with neutrals and grounds separated
- GFCI and AFCI protection where the code requires it
- Labeled directory at both the main panel and the subpanel
Doing it so the next project is easy
The cheapest subpanel job is the one you never have to redo. We routinely set a larger enclosure than the current circuit count needs and pull a feeder with room to grow, because the garage that gets a shop today gets an EV charger in three years.
That is a small cost at install and a large saving later. We will show you both options in the quote and let you decide.
Our process
How an EPO subpanel install job runs
- 01
Walk the space
We look at the main panel, the route and the structure, and talk through the circuits you want now and later.
- 02
Load calculation and quote
We calculate the load, size the feeder and the subpanel, and give you a written fixed price.
- 03
Permit
We pull the permit with your jurisdiction and schedule the work around your access to the space.
- 04
Install day
Feeder run, trench if needed, subpanel set, circuits landed, grounding done, everything labeled and tested.
- 05
Inspection and walkthrough
We meet the inspector, close the permit and walk you through both directories before we go.
Pricing
What moves the price on this job
We quote after seeing the equipment, because these details change the number more than anything else.
- Distance between the main panel and the subpanel
- Attached versus detached structure
- Trenching length, and whether it crosses concrete or landscaping
- Feeder amperage and conductor size
- Number of circuits landed at install
- Available capacity at the main panel
Monthly payments available through Hearth
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FAQ
Common questions
Can I add a subpanel without upgrading my main panel?
Sometimes. It depends on how much of your main service is already spoken for. The load calculation answers it, and we do that before quoting.
How big should a garage subpanel be?
Sixty amps handles most shops with 240-volt tools. If an EV charger is coming, 100 amps is usually the better buy while the trench is already open.
Do you do the trenching?
Yes. Trench, conduit, burial depth, backfill and basic restoration are part of the quote for detached runs.
Does a subpanel need its own ground rod?
A detached structure does, with the neutral and ground kept separate at the subpanel. A subpanel inside the same building does not.
How much does a subpanel installation cost?
Feeder length, whether the run is trenched or interior, and the amperage set the price. We measure the run on site and put one fixed number in writing.
Do I need a permit for a subpanel in Denver?
Yes. Subpanels and their feeders are permitted and inspected work in Denver and every surrounding jurisdiction we serve. We pull the permit and meet the inspector.
How long does a subpanel install take?
An interior subpanel is typically a half to full day. Detached runs that require trenching usually take one to two days depending on distance and ground conditions.
How deep does the trench need to be for a garage feeder?
Burial depth depends on the wiring method and whether it is under a driveway. We size the conduit and depth to code and handle backfill and basic restoration as part of the quote.
Can a subpanel power an EV charger in a detached garage?
Yes, and that is one of the most common reasons homeowners call us. Sizing the feeder at 100 amps while the trench is open costs far less than reopening it in two years.
Will a subpanel overload my main service?
Not if it is designed correctly. The load calculation tells us how much capacity is actually free, and we size the subpanel to what your service can carry.
Still deciding?
The fastest way to get a real answer for your home is to have a tech open the panel. The on-site estimate is free, and you leave with a written price for subpanel install.
Want the long version first? Read What Your EV Charger Needs From Your Electrical Panel.
Where we work
Subpanel Installation across the Front Range
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