What Size Sub Panel For Workshop? (+ Estimated Cost)

Workshops can be located anywhere in your home, but the garage is the most common. It contains a lot of electrical devices. But, for the smooth running of these appliances, you need the right size of sub-panel with the breaker. 

The right size sub-panel for a workshop would be at least 60 to 100 amps. The size can increase, decrease, or remain in between depending on the number of appliances you introduce in the workshop. The cost range stays between $200 and $3,000, including the labor, permits, and wires.

Different appliances will draw different amounts of amps. That is why the exact sub-panel size varies. This guide will help you know the approximate size of the sub-panel and the estimated cost. 

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Will a workshop need a sub-panel?

A workshop is where you work with a small group of people. 

You will require a lot of electrical appliances and a breaker to run them for work.

The breaker won’t be enough if these appliances have high wattages and draw too much current. 

In that case, you require a sub-panel for your workshop that can handle the number of appliances inside it.

How do I determine the sub-panel size for my workshop?

To determine the right sub-panel size for your workshop, you must determine the number of appliances used and the number of people working there.

If you wish to use the workshop only for yourself, you will require a few materials that will not draw too much current and, thus, will not require any higher amps. 

But, if you want to run a small business with a small group of people, you will want to add more heavy appliances. 

Since these appliances will draw excessive current, you need higher amps to control them. 

You also have to set up the workshop’s power service with a separate meter from the utility company. 

This method is cheaper than running underground power lines from your house. 

It depends on the design of your house. 

You have to calculate the wattage of the appliances and then decide the right sub-panel size for your workshop. 

You can take help from the electrician by informing him about the number of appliances and the wattage. 

What size of sub-panel do I need for my workshop?

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There is no exact size of sub-panel to suggest for a workshop. 

It completely depends on how many electrical appliances you have added to the workshop and how much power they draw.

Generally, the approximate size of a workshop should be around 60 to 100 amps from your house or the main circuit breaker. 

It means your house should have at least a 200 amp main breaker panel with a 120-volt single phase to power your house. 

The sub-panel will feed from the main breaker. So, you must ensure that the main breaker size is either the same or higher than the sub-panel breaker. 

As I said, you need to calculate the appliance’s wattage and the number of amps. 

For example, a basic load is 30 watts per square meter. 

So, if you have a workshop around 20 feet by 30 feet, it equals 600 square feet or 56 square meters. 

That means the wattage would be 1,680 watts. 

The basic lights and plugs use this much wattage. 

In that case, a 10 amp sub-panel would be a better choice. 

Below is a list of appliances commonly used in a workshop and the number of amps they draw:

AppliancesNumber of amps
Table saw15 amps
Skill saw5 amps
Welder15-20 amps
Drill press2-15 amps
Grinder1-15 amp

Along with these, you have to introduce some lights and plugs. 

Adding all these up, you will get a rough figure of 60-70 amps, which is close enough to 60 amps. 

You can also use an 80 amp sub-panel to be safe. 

You can also add 1-2 electrical materials in the future.

In that case, you can use a sub-panel that measures between 60 and 100 amps. 

Most workshops have 100 amps because these appliances will easily run with this sub-panel. 

Besides, you can also add up a few materials later in the future. 

Some people add air compressors, arcs, and plasma cutters. 

These workshops will need a 100 amp sub-panel. 

What size of wire do I need for the sub-panel?

The size of the wire depends on the sub-panel size. 

If you have a 100 amp sub-panel, common in most workshops, you can run a 4 gauge copper for hots and neutrals and a 6 gauge bare copper for grounding. 

If you run aluminum wires, choose 2 gauge aluminum. 

Since it is a sub-panel you are talking about, you need separate ground and neutral wires and terminals. 

So, you have to remove the green bonding screw on the neutral bus bars.

If the workshop is detached, you must put a grounding rod for the sub-panel. 

Here is a list of different wire sizes for different sub-panel amps:

Sub-panel ampsWire sizes
60 amps6 gauge copper or 4 gauge aluminum
80 amps3 gauge copper or 1-2 gauge aluminum
100 amps3 gauge copper or 1 gauge aluminum

If you have a detached workshop, the wire size would be:

Detached workshopWire size
60 amp 100 feet away#3 gauge THHN/THWN wire with 100 amps
100 amp 100 feet away#0 or 1/0 gauge THHN/THWN wire with 150 amps

Using an oversized wire is no problem because a bigger wire will keep the breaker safe and reduce the voltage drop. 

It will further reduce the chances of short circuits and electrical fire accidents. 

But, if the wire is smaller, the voltage drop and resistance will increase. 

That will lead to wire melting and fire hazards. 

So, either you choose the right wire size or an oversized wire. 

Also read:

How much will it cost to install a sub-panel in the workshop?

The cost to install a sub-panel highly depends on the panel’s amp. 

Generally, installing a sub-panel may range between $400 to $1,750. 

Different factors affect the installation price, like sub-panel cost, labor, work challenge, location, wire, etc.

An approximate cost of the sub-panel installation for a workshop can be:

Since you will have to use a few electrical appliances in the workshop, it is best to use a 60 amp sub-panel as the minimum panel. 


The cost for a sub-panel is the first important factor. Different amps have different prices. 

For example, a 100 amp sub-panel will cost around $100 to $200. 

A 50-60 amp sub-panel will cost $100 or less than that. 

Wire cost 

The next important factor is the wires. 

It, again, depends on the material. Copper is more expensive than aluminum wires. 

The wire cost also varies based on the distance. 

For example, a 2 gauge copper wire for 500 feet will cost around $800. Aluminum will be much less. 

If you wish to replace old wiring, that would cost around $600 to $2,000.

Labor cost 

You have to pay the laborers for their per-hour work. 

That would cost around $50 to $100 per hour. 

Depending on the work challenge and location, the cost may be either low or higher. 

In the urban areas, the labor cost will be more than in the rural areas. 

Underground line cost

You have to pay extra for the conduits and to trench to run underground power lines. 

That will cost more than $1,700 and reach nearly $2,000 to $3,000.

The location is another important factor. The cost of the urban areas is 10 times higher than the rural areas. 

If any underground power lines are required, you have to add the conduit and trenching costs:

  • Trenching – $8 per linear foot and $1.60 per linear foot for trenching fallback.
  • Digging machine for rent – $300 to $550.
  • Conduit – $12 to $17 per linear foot. $0.25 extra per foot for non-metallic PVC.

Also read: How Much Does It Cost To Run Power Lines Underground?

What size of breaker does a workshop need?

A workshop will need a 50 or 60-amp breaker to run the appliances. 

A workshop will contain multiple electrical appliances, some of which will draw a lot of power. 

You can also use a 100 amp breaker if you introduce a space heater, a mini split air conditioner or room heater, etc. 

A 100 amp breaker will not only allow the appliances to run smoothly but also allow you to add more appliances in the future. 

If you think the number of appliances is too much for the breaker, don’t worry, as the sub-panel will handle the remaining load. 

Wire size

The wire size for a 50 or 60-amp breaker would be 4 to 6 gauge. 

For 100 amp breakers, it would be 1 or 2-gauge wire. 

Cost to install the breaker

The average cost to install a breaker in the workshop is around $100 to $300. 

It will be more depending on various factors. 

How far will the sub-panel be from the main panel?

A sub-panel should be far enough from the main power source if the sub-panel has a main circuit breaker or shut-off disconnect. 

Sometimes, the local or NEC codes allow the sub-panel to get installed without the main breaker. 

But, it is applicable if the main panel’s building is attached to the workshop. 

There is no maximum or minimum distance between the sub-panel and the main panel.

There is no problem with less distance. 

But deciding the maximum distance, you must consider the voltage drop. 

The longer the distance, the higher the resistance. 

To reduce the wire resistance, you must use a thicker gauge and copper wire. 

Copper wire has higher resistance than aluminum and thus can be used for longer distances. 

What else do you need to consider while determining the sub-panel for a workshop?

Another factor is the heat. 

Having appliances that heat up easily will take up the maximum amount of amperage from the sub-panel.

So, you must be careful when choosing the sub-panel and the appliances to add to the workshop. 

Appliances like wall-mount heaters will heat up quickly and draw up to 50 amps. 

Avoiding these appliances is unnecessary because they are helpful and cost-effective. You only need to choose the sub-panel carefully. 

Heat sources for the workshop

Your workshop will require some heat sources to keep the workshop warm. 

There are a lot of appliances to help you out with that. 

But, some of them can draw excessive amounts of power. 

If you use certain methods to draw less power and heat the workshop, you can reduce the sub-panel size too.

Here are some heat sources:

  • You can use propane stoves to heat up quickly. You can run them on smaller tanks. 
  • Heat in the workshop can run through the floor in the form of pipes and fill it with glycol. The heat source would be oil-fired propane.
  • A wood stove is very good and also cost-effective. 
  • Another is a pellet stove. The pellets are cheap, and the stove is easy to install in the workshop. It draws less than 2 amps and helps reduce the size of the sub-panel.

Whatever appliances you wish to choose for your workshop, always consult an electrician before taking any major steps. 

How many circuits are allowed in a panel?

In 2008, the NEC or National Electric Code allowed at least 42 circuits in one panel. 

But now, you can add larger circuits in the main panels or sub-panels. 

The number of circuits to add depends on the sub-panel rating in amps and the panel design.

It is easy to find the right one where you can add as many circuits as you want. 

Breakers come in either single-pole or double-pole. 

You can try the following breakers:

Final thoughts

There is no exact size of the sub-panel for the workshop. 

It highly depends on the number of appliances you wish to run. 

The sub-panel size for a workshop should always remain between 60 and 100 amps. 

100 amp is considered the best because you can add multiple heavy appliances. 

You can also add a few more appliances later if needed. 

The cost ranges between $400 and $1,700.

It will be either less than $1,000 or more than $2,000 depending on the location, labor cost, wire, underground wires, and many more.

You can try the heat sources I shared to reduce the size of the sub-panel. 

That will help you in saving some amount of money. 

Reference: National Electrical Code, NEC Wire Table,  Electrical wiringHome wiring.

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Arthur Smith

Howdy! I am Arthur Smith, an electrical engineer who is extremely passionate about electronics. I have lived in different parts of the US and currently reside in Wisconsin. I am one of those rare children who knew what he wanted to study and do in life right from the start. I was a curious child who wanted to know how switches work and how the AC works, and I would always observe my dad whenever he would handle the wires and fix things around the house. I currently work as an electrical engineer at a reputed company and write for this blog. And I read loads of books or play video games in my free time.

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