When I built my first shed years ago, I decided quickly that I need electricity for some lights and use my tools. Wiring the inside of my shed was easy, but I wasn’t sure what size wire to run to a shed.
The size of the wire you run to your shed depends on how far away it is and whether you use 120V or 240V. If your shed is 50 feet from your breaker box, you can use 10/2 AWG UF-B wire for a 120V circuit up to 20A. This will allow you to run multiple machines at the same time while providing light to your shed.
The above circuit will provide plenty of power for some lights and a couple of 120-volt outlets. If you are looking to power some heavy equipment, such as a welder, then you’ll have to upgrade to a higher amperage breaker and a lower gauge wire.
Below we’ll take a look at all your options for using different sizes of wire, including wire types, gauges, and conduit.
Quick Navigation
- What Size Wire to Run to a Shed
- What Wire to Use for 240 Volts
- What Wire Size to Use: Examples
- What Happens If Wire Gauge Is Too Big?
- Can I Use Oversized Wire?
- What If My Wire Size is Too Small?
- What Size Breaker Do I Need for a Shed?
- How Far Can You Run 10 Gauge Wire?
- Can I Use an Extension Cord to Power My Shed?
- Do I Need to Bury the Wire?
- Conclusion
What Size Wire to Run to a Shed
Most shed owners need a couple of outlets and some lights to see what they’re doing. Typically the most amps you’ll need are a little over 15 to run your lights and a miter or table saw simultaneously. Use a 20 amp breaker and 10/2 AWG UF-B wire.
Here’s why: a 20 amp breaker will ensure you don’t trip your breaker when operating your tools and lights at the same time. Heavier equipment like a miter saw is rated up to 16 amps. While that doesn’t mean that it will operate at 16 amps all the time, it does indicate that it can get close to it. Thus, when combined with lights, then a 15 amp breaker is not enough. Go 20.
Typically in your house, you’ll use 14 gauge wire with your 15 amp, 120-volt breakers, and 12 gauge wire with your 20 amp, 120-volt breakers. So why not just use 12 gauge wire to run to your shed?
Using 10/2 wire for your shed will allow you to upgrade to a 30 amp breaker in the future. This saves you from removing the 12 gauge wire from the conduit and then fishing new wire back through the conduit.
If you are dead set that you’ll never want to upgrade your amperage – which would allow you to run an electric heater plus power tools – then 12/2 AWG UF-B wire is perfectly fine. The wire is the appropriate gauge for a 20 amp breaker.
What Wire to Use for 240 Volts
Bringing 240 volts to your shed means that you want to operate something like an electric fireplace or welder. If this is the case, you’ll need either a 50 or 60 amp breaker in your main subpanel.
Use 6/3 AWG UF-B wire will allow you to bury it directly into the ground, and is a low enough gauge to safely supply power for your 240-volt circuit in the shed.
If you are going to be using lower-rated 240-volt devices, such as a window air conditioner, then you can use a 30 amp, 240-volt breaker in conjunction with 10/3 AWG UF-B wire.
Last – always be sure to check the voltage requirements and total wattage of the device you intend to use. Remember the old formula – volts x amps = wattage. Not all devices are created equal, so while your neighbor might run a power tool on a 15 amp circuit with 14/2 wire, it doesn’t mean you can. Always read the labels first.
What Wire Size to Use: Examples
The longer the circuit, the less ability that circuit has to provide voltage – this is called “voltage drop”. Wire releases heat, which is essentially electricity loss. The longer the wire, the more heat that is lost.
If you run wire to a shed that is far from your house, you might experience the results of voltage drop – tools that don’t run up to maximum power, dim lights, etc. That’s because your 120-volt circuit is more like 108 volts…or less!
One way to compensate is to get thicker wire, which will lessen the resistance of the current and reduce voltage drop. Remember, the thinner the wire, the more resistance – and heat loss. Make the wire thicker, then you get less resistance.
Let’s take a look at the size of the wire required for running a circuit to your shed from your main panel in your house.
Note: the following calculations are in line with national regulations that stipulate a 3% voltage drop being the maximum allowable loss in a circuit.
- 150 Foot Run – A 120-volt circuit on a 20 amp breaker will require 6/2 AWG wire for 150 feet.
Above, we mentioned that your shed should use a 10/2 wire when running power from a 20 amp breaker to your shed for 120 volts. However, that will only work if your shed is 85 feet or less from your breaker box.
A 150-foot, 240-volt circuit running on a 30 amp, the double-pole breaker would need 8/3 AWG wire supplying the shed from the breaker box.
- 300 Foot Run – a 120 volt, 20 amp circuit would require 4/2 AWG wire. A 240 volt, 30 amp circuit would require 4/3 AWG wire.
- 500 Feet – a 120-volt, 20 amp circuit would require 1/0 AWG wire. A 240 volt, 30 amp circuit would require 3/3 AWG wire.
Keep in mind that a 3% voltage drop is minimal. If you were to use 8/2 wire for a 150 foot run to a shed on a 20 amp breaker, chances are you wouldn’t notice the drop. Why? You’d have to be running multiple machines at once on full power to achieve 20 amps.
While I don’t recommend going over the 3% voltage drop parameters, understand that many people will use a higher gauge than dictated by a voltage drop calculator and see no difference in the performance of their power tools or devices.
What Happens If Wire Gauge Is Too Big?
You’ll come to find when you go to your local home reno store that wires come in all shapes and sizes. You might be tempted to overcompensate when wiring your shed. For instance – what if you take up welding or put in an electric furnace in the future? You’ll need a larger wire.
Therefore you don’t want to shell out for a wire that might be adequate in the meantime but not adequate for future needs. Can you simply put a larger gauge wire with a lower voltage and amperage circuit?
Can I Use Oversized Wire?
Yes, you can use a larger, oversized wire with a smaller circuit. You won’t see any decrease – or increase – in performance of the circuit.
The only benefit is that you will reduce the voltage drop in the circuit – although it will likely be negligible in the first place.
You don’t want to supply 240 volts to your shed and then discover you need 6/3 and not 10/3. There is no harm in using a lower gauge of wire when a higher gauge will suffice. It gives you room to expand without having to replace the wire.
The benefits of using a larger gauge of wire include:
- Gives your room to increase the amperage of your breaker in the future without changing wire size
- Reduces the voltage drop in the circuit, improving the ability of devices on your circuit to perform at max power
What If My Wire Size is Too Small?
Using wire that is too small for the circuit could result in damaged devices, burnt wires, or fire. For instance, the use of 14 gauge wires on a 20 amp circuit will result in too much resistance within the wires. This will manifest itself in excessive heat, which could melt wire insulation and cause a fire in your house or shed.
At the very least, the wire insulation can melt slowly over time and cause a shock hazard. If it is near insulation or something else that is flammable, then you have an extreme fire hazard.
What Size Breaker Do I Need for a Shed?
A shed requires different considerations than a house when considering power supply needs. Your shed will see less frequent power usage, but when it is used, the wattage of the devices operated will be much higher. Saws, compressors, grinders – they all use serious watts.
Therefore, wiring your shed for 15 amps is a mistake. You may not be able to use a miter saw and a light at the same time, for a more powerful miter saw.
Use a 20 amp breaker with the wiring recommended above, and you’ll be able to power multiple tools and lights all on the same circuit.
If you need 240 volts in your shed for a larger device like a welder, it depends on how many watts the device will need to use. A 30 amp breaker will suffice for 240-volt appliances like a window air conditioner. A 60 amp breaker will likely be required for a welder.
How Far Can You Run 10 Gauge Wire?
You can run a 10 gauge wire up to 85 feet on a 20 amp circuit. If you opt to use this type of wire on a 15 amp circuit, it can run up to 115 feet. After these distances, the circuit will go over the recommended 3% voltage drop.
You can run a 12 gauge wire up to 70 feet on a 15 amp circuit. That number drops to 50 feet if you run 12 gauge wire on a 20 amp circuit.
Can I Use an Extension Cord to Power My Shed?
Yes. But I would not recommend using an extension cord to power your shed as a permanent solution.
While this is a quick and easy fix for getting power to your shed, the dangers of having an extension cord permanently sitting between your house and shed is not a good idea, and here’s why:
- It could break, rip, or tear.
- It’s a hazard to others in the yard.
- It’s inconvenient if you want to plug in more than one device.
- You can’t light your shed and use a tool at the same time.
Do I Need to Bury the Wire?
Yes. The only type of wire you are allowed to use outdoors is wire with the acronym “UF”, which means “underground feeder”. You can usually bury this type of wire either directly or in a conduit.
If you choose to bury the wire directly in the earth, then you’ll have to dig down 24 inches. If using conduit, 18 inches is enough.
If you are only running one circuit to your shed, then you won’t need a subpanel. You will, however, need a shut-off switch where the power enters the shed. This can simply be a light switch that controls all outlets and fixtures in the shed.
With more than one circuit, you need a subpanel, which can be found in this article explaining how to run electricity to a shed.
Conclusion
Whenever you are dealing with electricity, safety is of the utmost priority. Make sure you power off your main shutoff breaker when installing a new breaker in your box. Connect newly installed shed wiring to the breaker box last, so you don’t risk a shock when installing the wiring or receptacles.
Wiring can be confusing, and I hope this article was able to clear up any questions you had about what size wire to choose for your shed. Remember, never take a chance or guess with electricity. If you are still uneasy about wiring your shed or choosing a wire size, consult with an electrician.
As always, thanks for taking the time to read this article. Please drop me a line or comment below if you have any questions or want to share your own experiences choosing a wire size for your shed.
Eugene Sokol
Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. He is passionately interested in home improvement, renovation and woodworking.
FAQs
How Far Will 6 gauge wire carry 50 amps? ›
For every 100 feet, voltage drops by 20%.
Example: 50 amp wire is usually the 6 AWG (we require at least 62.5A and 6 AWG can handle 65A). If you have to power an electric device 100 feet away, you need 20% amps more.
For 30 amp service 100 feet away you would need a wire that can handle at least 45 amps. Luckily, the #8 AWG wire has a 50A ampacity. You can use the #8 AWG wire for sub panel 50 feet, 100 feet, and even 150 feet away.
How far can 12 gauge wire run? ›NEC (in the US) recommends no more than 3% voltage drop. For 12-gauge wire, operated at 20 amps, that would 51 feet. At that round-trip distance, there'd be 2.95% voltage drop.
How do I calculate what size wire I need? ›How do you determine cable wire size? Divide the voltage running through the cable by your target current. If, for instance, 120 volts will act on the cable, and you want 30 amps to run through it: 120 / 30 = 4.
Will #8 wire carry 50 amps? ›8 AWG may carry a maximum of 70 Amps in free air, or 50 Amps as part of a 3 conductor cable.
What size wire do I need for 50 amps at 150 feet? ›To run 50 amps at 150 feet, you can use No. 4 AWG. The larger the wire diameter is defined by the smaller numbers on a wire.
What size wire should I run to my shed? ›Use 6/3 AWG UF-B wire will allow you to bury it directly into the ground, and is a low enough gauge to safely supply power for your 240-volt circuit in the shed.
Will a 12 2 wire carry 30 amps? ›Can You Use a 12-2 AWG for 30 Amps Circuit. Yes, based on the National Electric Code or NEC, you can use 12-2 AWG cables for THHN or THWN-rated wires. These cables are made for general purposes and can hold up to 194 degrees without taking any damage.
What happens if you put a 30 amp breaker on 12 gauge wire? ›12 gauge wire is capable of conducting about 20 amps. If you would use 30amp breaker, your wire will get hot long before breaker with cut off the current, what may lead to overheat, melt the isolation and make short circuit (and even fire).
How far can you run 12 gauge wire without a voltage drop? ›NEC (in the US) recommends no more than 3% voltage drop. For 12-gauge wire, operated at 20 amps, that would 51 feet.
How many outlets can you run on a 12 2 wire? ›
For general use receptacles, In commercial buildings it is limited to 180VA per duplex or single receptacle, therefore on a 12/2 Romex cable not otherwise subject to ampacity derating and protected by a 20 amp circuit breaker, that would allow a maximum of 13 receptacles.
What size wire do I need to run 200 feet? ›What size of wire do you need to run 200 feet? 30ga works if you are carrying small signals, although having an “active terminator” becomes critical due to the capacitance effects on such a long wire.
How far can you run 10 2 wire on a 30 amp breaker? ›Other Things You Need to Consider When Installing a 30 Amp Circuit Breaker. You must also consider the wire length for your 30-amp circuit, in addition to the wire AWG. A maximum length of 150 feet is allowed when using a 10-gauge wire size.
How far can you run 14 gauge wire on a 15 amp circuit? ›For a 120-volt circuit, you can run up to 50 feet of #14 AWG cable without exceeding 3% Voltage Drop on a 15 amp circuit.
Can wire size be too big? ›If a wire gauge is “too big” then it is a lot more expensive and is harder to bend, as well as more difficult to attach with wire nuts or to switches. Other than that, not much of anything.
How far can you run 8 gauge wire for 40 amps? ›The rule of thumb is to go up one size larger if you plan on running the recommended wire size over 100 feet. This means that if you are planning on running 8-gauage wire for a 40 amp breaker over 100 feet, you should go to 6-gauge wire.
How far can I run #8 wire? ›| 14 AWG | 50 feet |
|---|---|
| 12 AWG | 60 feet |
| 10 AWG | 64 feet |
| 8 AWG | 76 feet |
| 6 AWG | 94 feet |
Stipulates how far you can run the wire. If you're looking to use the full 50 amp then it is safe to say that any more than 100 feet and you will need to increase the wire size past number six. We use the 100 foot rule as a rule of thumb for voltage drop. This is assuming that you were using a 120 or 240 V circuit.
What size wire do I need to run 50 amps 200 feet? ›Calculating With Voltage Drop Considered
On the off-chance that your panels are rated at 110V/120V, the right wire size for 50 amp sub panel should be bumped up to 2 AWG copper or 1/0 AWG aluminum for 200 ft.
8-gauge copper will handle fifty amps, but it will get hot (75 degrees C).
Will 12 gauge wire carry 50 amps? ›
“Twelve-gauge wire is good for 20 amps, 10-gauge wire is good for 30 amps, 8-gauge is good for 40 amps, and 6-gauge is good for 55 amps,” and “The circuit breaker or fuse is always sized to protect the conductor [wire].”
What cable do I need from house to shed? ›If you need power for your shed, or any other type of outbuilding, then you'll need for it to be connected to the mains via an SWA cable. This stands for “steel wire armoured” cable and is ideal for the job as it's waterproof and not prone to rotting.
How do I run wire from my house to my shed? ›To run electricity to a shed or outdoor building, start by planning out the the electrical cable routing. Next, add a GFCI outlet to the home's electrical panel and route the the new circuit wire to the home's exterior. Excavate your electrical cable trench and install conduit.
What do I need to run electricity to my shed? ›In this case, you'll only need lights, receptacles, wire, a switch, and maybe some conduit. Another point to consider is if you want to supply 240V instead of 120V to your shed. All lights, most outlets, and appliances operate at 120 volts.
How many outlets can you put on a 20 amp breaker? ›How many outlets can be put on a 20 amp circuit safely? A rule of thumb is to factor a maximum draw of 1.5 amps to each receptacle, which means you can put 10 outlets on a 20-amp circuit.
How far can you run 30 amp wire? ›How far can 10 gauge wire carry 30 amps? 30 amps carried over a 10 gauge wire is not meant to be run over far distances. If you plan on going over 150 feet, you should upgrade the wire size from 10 gauge to 8 gauge.
How many outlets can you put on a 15 amp breaker? ›Technically, you can have as many outlets on a 15 amp circuit breaker as you want. However, a good rule of thumb is 1 outlet per 1.5 amps, up to 80% of the capacity of the circuit breaker. Therefore, we would suggest a maximum of 8 outlets for a 15 amp circuit.
How many outlets can you run off a 30 amp breaker? ›A good rule of thumb is to put a maximum of 16 outlets on a 30 amp circuit.
Can you mix 12 gauge and 14 gauge wire on a 15 amp breaker? ›12 is 20 amp, 14 is 15 amp. As long as the circuit has a 15 amp breaker, you can mix them.
Can I go from a 20 amp breaker to a 30 amp breaker? ›Yes. You can replace a 20A breaker with a 30A in a Standard Electrical Panel Board. However, if the circuit conductors are #12 AWG Copper, do not replace the 20A breaker with 30A. A #12 AWG Copper wire has an ampacity of only 20A.
Does length of wire affect amperage? ›
Relationship between the length of a wire and it's AWG/amperage rating: none. Relationship between AWG and amperage rating: basically, AWG is linked to wire diameter/cross-area. The higher is the cross-area, the higher is the ampering rating.
How far can I run a 20 amp circuit on 12 gauge wire? ›12 AWG wire. This wire will safely carry 20 amps up to 100 feet. If you plan on going over 100 feet, or if you want to run the wire in conduit, you should upgrade to 10 gauge copper wire.
What size wire do I need to run 1000 feet? ›The most common type of wire is copper THHN and you would need 6 awg wire .
Can I run two wires through the same hole? ›If the hole is not fire-stopped or draft stopped there is no limit as to how many cables you can run through it. If it is filled then derating begins when you install more than two cables. You could possibly install 4-14/3 or 4-12/3 cables in a fire or draft stopped hole with no effect on the final conductor ampacity.
How many outlets can you put on a 20 amp breaker with 12 gauge wire? ›The answer to the question how many outlets on a 20 amp circuit is ten outlets. Always comply with the 80% circuit and breaker load rule, allowing a maximum load of 1.5 amps per receptacle. Remember that your circuit, wire sizes, and outlets must be compatible to avoid overheating and electrical hazards.
Can I put lights and outlets on the same circuit? ›Basic answer to your question of can a mixture of lights and receptacles be installed on a single circuit is yes.
What wire size do I need to go 100 feet for a 100 amp service to a workshop? ›If you check the wire size chart (you have the link in the introduction), the #0 AWG wire (also known as 1/0 AWG wire) has 150 ampacity. That means that #0 AWG wire is the perfect size wire for 100 amp service 100 feet away.
How far can you run 2 AWG wire? ›Example calcuation 2 - Aluminum Wire, 1 phase power
Cable run: 400 ft.
For this to operate, you'll need conductors that are 1 AWG copper or 2/0 aluminum-clad wiring. This has to be a wire gauge sufficient to transport those 100 amps safely.
Can you land 2 wires on a breaker? ›When it's NOT a defect: Double tapped wiring is ok if the circuit breaker is designed for two conductors. If a circuit breaker is designed for two conductors, it will say so right on the circuit breaker, and the terminal of the circuit breaker will be designed to hold two conductors in place.
How many amps can you put on a 10 2 wire? ›
10 Gauge Wire (10/2 Wire, 10/3 Wire, 10/4 Wire): How Many Amps Can 10 Gauge Wire Handle? 10 gauge wire is a very popular wire thickness, often used for speakers, extension cords, home wiring, and other electric systems where wires can handle 20-30 Amps.
Can you use a double pole 30 amp breaker as a single pole? ›Can I turn a double pole 30 amp breaker into a single pole 30-amp breaker? Yes, but it's exceptionally rare that, in the US, that you should.
What happens if you use 12 gauge wire on a 15 amp circuit? ›You might wonder if it is safe to use 12-gauge wire on a 15 amp circuit. While it is not unsafe, using wire of a lower gauge can lead to a higher risk of overloading. Wire of a lower gauge will generally not be as sturdy as a higher-gauge wire, so using a larger one on a 15 amp circuit is safer.
How many outlets can I put on a 15 amp 14 gauge wire? ›14/2 wire on a 15-amp circuit can power 8 receptacles. Since most outlets have 2 receptacles, you can typically wire 4 outlets to a single 15-amp circuit using 14/2 wire. If you want to put additional outlets on the circuit, step up to a 20-amp outlet with 12/2 wire.
Can 14 gauge handle 30 amps? ›Is it safe to have a 14 gauge wire on a circuit protected by a 30 amp breaker? No, 14 gage wire uses a 15 amp breaker. A 30 amp breaker will allow twice the current a 14 gage wire can handle and can overheat the wire - fire hazard.
How do I choose a wire size? ›To determine what gauge wire you need, consider the carrying capacity and the amount of current the wire needs to conduct (measured in amperage or amps). Wire gauge is directly related to how many amps you need to run through it. The distance you need the wire to go can also impact the gauge of wire you need.
Does thicker wire conduct more electricity? ›The thin wire will conduct electricity, but there is more electrical resistance. The thicker wire is like the four lane highway. There's a lot less electrical resistance, and as a result, that light bulb burns brighter because more electricity can reach it.
Do thicker wires get hotter? ›The resistance of a wire depends on its thickness and length. The longer the wire the greater the resistance offered to the flow of charge. Thick wires have less resistance than thin ones. Current tends to create heat in high resistance wires.
› wires-and-circuit-bre... ›What Size Wire for My Breaker Do I Need?
What gauge wire is proper for a 200 foot distance
Electrical Wire Size Required for Receptacles, How to choose the ...
For a maximum of 50 amps, you'll need a wire gauge of 6. Fifty amp breakers are most often used to power many different appliances. However, a kitchen oven can alone require 50 amps.
What size wire do I need to run 50 amps 200 feet? ›
Calculating With Voltage Drop Considered
On the off-chance that your panels are rated at 110V/120V, the right wire size for 50 amp sub panel should be bumped up to 2 AWG copper or 1/0 AWG aluminum for 200 ft.
1,000 feet would be the maximum distance for a 6 gauge wire. You should not put a wire that size running the maximum distance in a conduit otherwise you will get Eddy currants that will cause any number of unwanted effects.
How many feet can 6 gauge wire run? ›...
For 240-volt circuits:
Other Things You Need to Consider When Installing a 30 Amp Circuit Breaker. You must also consider the wire length for your 30-amp circuit, in addition to the wire AWG. A maximum length of 150 feet is allowed when using a 10-gauge wire size.
How far can you run 12 2 wire on a 15 amp breaker? ›You can run a 12 gauge wire up to 70 feet on a 15 amp circuit. That number drops to 50 feet if you run 12 gauge wire on a 20 amp circuit.
Will a 12 2 wire carry 30 amps? ›Can You Use a 12-2 AWG for 30 Amps Circuit. Yes, based on the National Electric Code or NEC, you can use 12-2 AWG cables for THHN or THWN-rated wires. These cables are made for general purposes and can hold up to 194 degrees without taking any damage.
What size wire do I need for a 200 amp service 200 feet away? ›The Short Answer: For a 200 amp service, you'll need a #4/0 aluminum wire.
What size wire do I need to run 50 amps 300 feet? ›You will likely need 2 AWG but that's going to be less than 4 AWG Cu. Secondly, you may want to consider running a conduit vs. direct burial. That way you can upgrade in the future.
What size wire do I need for 50 amp 220 volt? ›As you can see from the graph, a 6 AWG is the safe choice if you have a 220v 50 amp that you need to power. A 12-gauge is the right wire size for your 220v 20 amp needs.
What cable do I need to run power to my shed? ›One of the most frequently asked questions is what outdoor electrical cable do I need to power my shed? The answer is armoured cable.
What size wire do I need to run 200 feet? ›
What size of wire do you need to run 200 feet? 30ga works if you are carrying small signals, although having an “active terminator” becomes critical due to the capacitance effects on such a long wire.
How do I run electricity from my house to my shed? ›To run electricity to a shed or outdoor building, start by planning out the the electrical cable routing. Next, add a GFCI outlet to the home's electrical panel and route the the new circuit wire to the home's exterior. Excavate your electrical cable trench and install conduit.
Does thicker gauge wire use more electricity? ›The smaller wire loses more electricity to the heat loss than the larger capacity wire. For example, 100 feet of 12 gauge wire delivering 15 amps of current loses 77 watts of energy. A 10 gauge wire of the same length only loses 48 watts of energy when delivering the same load of current.
Will 6 gauge wire carry 60 amps? ›This is what all those homeowners that mistakenly use 6 AWG gauge wire for 60 amp breaker don't take into account. 6 AWG can only handle 65 amps. Here's what a professional will know: The next wire size that can handle more than 75 amps (as required for a 60 amp breaker) is the 4 AWG gauge wire.
Does distance affect wire size? ›If the wire is longer, despite the amperage rating of the circuit, would the wire need to be larger gauge? Yes. Typically, less than 3% voltage drop to wire is used. The gauge is defining roughly the cross-section area of the cable, which affects its resistance per unit length - and will affect how much it is heating.
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