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Cost guide

Subpanel Installation Cost

Adding a subpanel to feed a garage, basement, workshop, or addition when the main panel is full or distant.

Typical range
$900–$3,500
Most people pay
$1,800
Service life
25–40 years for the subpanel; feeder lasts indefinitely if properly installed

National cost range

National range, per subpanel installed

$900 – $3,500

Most homeowners pay around $1,800. The spread is real, not hedging — the drivers below determine which end of it you land on.

Low end
$900
Simple access, like-for-like
Typical
$1,800
What most jobs come in at
High end
$3,500
Upgrades, difficult access, code work

What you are actually paying for

Find the row that matches your situation. Quotes that differ wildly from each other usually differ in scope, not in price.

ScenarioTypical cost
60-amp subpanel, attached garage, short runFed from the main panel through one wall.$900–$1,600
100-amp subpanel, basement finishCommon for a finished basement with kitchenette and bathroom.$1,200–$2,200
100-amp subpanel, detached garage, 75-foot trenchUnderground conduit and ground rod at the detached structure.$2,000–$4,000
Subpanel for home additionSized to the addition's load; often 60 to 100 amps.$1,500–$3,000
Subpanel plus main panel upgrade to 200ARequired when the main service cannot support the added load.$3,000–$6,000

What moves the price

In descending order of impact. These are also the questions worth asking a contractor whose quote sits outside the range above.

  1. Subpanel size and feeder

    A 60-amp subpanel needs 6 AWG copper feeder. A 100-amp subpanel needs 2 AWG copper or 1/0 aluminum. The feeder run length drives voltage drop and conductor cost.

  2. Distance from main panel

    A subpanel in the garage on the other side of the same wall is cheapest. A detached garage 100 feet away needs a buried feeder in conduit at significant cost per foot.

  3. Main panel capacity

    The subpanel load counts against the main service. A 200A service can support a 100A subpanel if the calculated load allows. A 100A service may not have room for a large sub.

  4. Number of circuits needed

    A 6-space subpanel covers a small garage. A finished basement workshop may need a 20-space panel. Larger panels cost more but avoid a second subpanel later.

  5. Detached structure bonding

    A subpanel in a detached garage requires its own grounding electrode (ground rod) and a 4-wire feeder. Bonding mistakes here are a common inspection failure.

Can you do it yourself?

Not a DIY job

Subpanel installation involves feeder sizing, main lug connections, grounding electrode systems, and bonding rules that vary for attached versus detached structures. This is licensed electrician work.

Permits and inspection

An electrical permit is required. The inspector verifies feeder size, grounding, bonding, and that the main service can support the added load.
Run the DIY vs. pro decisionCheck a quote you already have

When this cannot wait

  • Main panel completely full with no room for tandem breakers
  • Finished basement or garage needing power but no available circuits
  • Workshop equipment tripping breakers on shared general circuits

Common questions

How much does a subpanel installation cost?
A 60 to 100-amp subpanel in an attached garage or basement typically runs $900 to $2,200 installed. A detached garage with underground feeder runs $2,000 to $4,000. Add $1,800 to $4,000 if a main panel upgrade is also needed.
What size subpanel do I need for a garage?
A standard two-car garage with lights, outlets, and a garage door opener needs a 60-amp subpanel. Add workshop equipment, an EV charger, or a small HVAC unit and size to 100 amps. Size the feeder to match.
Can I install a subpanel myself?
A homeowner can in some jurisdictions with a permit and inspection, but feeder sizing, grounding, and bonding for detached structures are common failure points. Most people hire an electrician for subpanel work.
Does a subpanel need a main breaker?
A subpanel in the same structure as the main panel does not require a main breaker in the sub — the feeder breaker in the main panel serves that function. A detached structure subpanel typically has a main breaker as the disconnect.
Main panel full with no room for more breakers — subpanel cost?
A 60 to 100-amp subpanel in an attached garage or basement runs $900 to $2,200 installed. A detached garage with underground feeder runs $2,000 to $4,000. This is almost always cheaper than a full 200A service upgrade at $1,800 to $4,000 — if the main service has amperage capacity.
Garage workshop needs more power — subpanel installation price?
A 100-amp subpanel for a garage workshop runs $900 to $2,200 attached, $2,000 to $4,000 detached with underground feeder. This supports welders, air compressors, and multiple tool circuits. Size the subpanel to your largest tool plus 25% headroom.
Adding a second subpanel because the first one is full — what does it cost?
A second subpanel runs $900 to $2,200 if the main service supports the added load. If the main is 100A and already loaded, you need a service upgrade ($1,800 to $4,000) before adding another sub. A load calculation ($150 to $300) answers this before you spend money.
Finished basement needs a panel — subpanel cost?
A 60 to 100-amp subpanel in a finished basement runs $900 to $2,200 including feeder from the main panel. Running the feeder through finished walls adds $200 to $500. Each new circuit from the subpanel runs $200 to $500.
Detached garage has no power — running a subpanel from the house cost?
Underground feeder from house to detached garage runs $2,000 to $4,000 for a 60 to 100-amp subpanel including trenching. Trench length is the main variable — budget $15 to $25 per foot. A main breaker disconnect at the garage is required by NEC.
Subpanel humming or buzzing — is it dangerous, and what does repair cost?
A humming subpanel usually means a loose breaker ($0 to tighten) or failing breaker ($50 to $150 to replace). Persistent buzzing with warmth or scorch marks requires immediate shutdown and electrician visit ($150 to $300 diagnostic). Do not ignore — loose connections cause fires.

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