Add Dedicated Circuits Where You Need Them
Electrical Sub Panel Installation in Missoula for garages, HVAC systems, and EV chargers that overload existing circuits
Edison Electric installs electrical sub panels throughout Missoula for homeowners who need to expand circuit capacity in specific areas of their property without upgrading the main service panel. You notice the need when you want to add an EV charger in your garage but your existing panel has no available breaker slots, or when your HVAC contractor tells you the new heat pump requires a dedicated circuit and your current setup cannot support it. A sub panel acts as a secondary distribution point fed from your main panel, allowing multiple new circuits to branch from a single feeder line.
Sub panels are installed when your main electrical panel has reached its circuit capacity but the overall service amperage remains sufficient for your home's total load. This situation arises frequently in garages where you add tools, lighting, and charging equipment over time, or in additions and remodels where new appliances require dedicated lines. In Missoula, where detached garages and workshop spaces are common, running a sub panel eliminates the need to route every new circuit back to a distant main panel inside the house.
If you are planning to install an EV charger, add a mini-split system, or wire a workshop and your main panel lacks space, reach out to discuss whether a sub panel fits your electrical load and layout.
How Sub Panels Expand Your Electrical Infrastructure
The installation begins with a load calculation to confirm your main panel can supply the additional amperage required by the sub panel without exceeding the service rating. Edison Electric sizes the feeder cable based on the sub panel's amperage and the distance from the main panel, accounting for voltage drop over longer runs. In a detached garage, this often means running larger gauge wire through conduit to maintain safe and efficient power delivery.
Once the sub panel is mounted and the feeder is connected, you gain access to multiple new breaker slots in the location where you need them. Your garage lights, outlets, EV charger, and air compressor each run on their own dedicated circuit, and you no longer trip breakers when operating equipment simultaneously. The sub panel is labeled clearly, and each circuit is tested to verify proper grounding and voltage at the point of use.

The work includes installing a main breaker in the sub panel, running the feeder through appropriate raceways, and ensuring all connections meet current code requirements. Sub panels do not increase your home's overall electrical capacity; they redistribute it more effectively across your property. If your main service is already undersized for your total load, a service upgrade may be required before adding a sub panel.
Common Questions About Adding a Sub Panel
Homeowners in Missoula often ask how sub panels differ from adding circuits directly to the main panel and whether their existing service can support the additional load.
What happens if my main panel has no empty breaker slots?
You can add a sub panel fed by a new breaker in the main panel, which then provides multiple new circuit slots at the sub panel location without altering the main panel's existing layout.
How far can a sub panel be installed from the main panel?
Distance is limited by voltage drop and wire sizing, but runs to detached garages or outbuildings up to 100 feet are common when the feeder cable is sized correctly for the load and length.
Why would I install a sub panel instead of upgrading my main service?
A sub panel works when your total service capacity is adequate but breaker slots are full, saving the cost of a full service upgrade while still allowing you to add new circuits in targeted areas.
When is a sub panel required for an EV charger?
A sub panel is not always required, but it is often the most practical solution when your main panel is full, located far from the garage, or cannot accommodate the additional breaker and wire size needed for a 240-volt charging circuit.
What size sub panel do I need for a garage workshop?
Panel size depends on the number and type of circuits you plan to run, but a 100-amp sub panel typically supports lighting, receptacles, a 240-volt air compressor, and an EV charger with room for future expansion.
Edison Electric evaluates your current electrical system and planned loads to determine whether a sub panel meets your needs and fits within your service capacity. Contact us to review your project and receive a detailed assessment of what the installation will involve.
