Most generators need big wires. You need a wire that can handle all the amps (+ accounting for 80% NEC rule) the generator produces. This is quite a well-known fact. However, exactly what size wire you need for a generator is quite difficult to find.
Using a wire that is too small will fry the wire or the circuit. That’s why it’s not a good idea just to pick the nearest wire to connect a generator.
To help figure out what size wire you need, we have created generator wire sizing calculators and charts for any generator (home, standby, portable, etc). If you know how many amp or watt generator you have, you can simply consult the generator wire sizing chart and you will know if you need an 8 AWG wire, 10 AWG wire, 12 AWG wire, and so on.
Example For Generator Wattage: Let’s say that you have an 8,000W generator running on a 220V circuit. What size wire do you need for an 8,000-watt generator? First, you need to calculate the amps like this: 8,000W/220V = 36.4A. Then you have to account for the 80% NEC rule by multiplying the amps by a 1.25 factor like this: 36.4A×1.25 = 45.5A. This means you need a wire with at least 45.5A ampacity. 8 gauge AWG copper wire has an ampacity of 50A; this is the wire size you need for an 8,000-watt generator.
Example For Generator Amps: This is easier. Let’s say you have a 50 amp generator. What size wire do you need for a 50 amp generator? You have to multiply the amps by a 1.25 factor (80% NEC rule) like this: 50A×1.25 = 62.5A. That means you need a wire with at least 62.5A ampacity. 6 gauge AWG copper wire has an ampacity of 65A; this is the wire size you need for a 50 amp generator.
These are just two examples. To adequately illustrate how generator wire sizing works, we are going to explain the whole calculation first.
Below the explanation, you will find very useful resources that will help you adequately determine generator wire size:
- Generator Wire Sizing Calculator. You basically input the wattage or amps of your generator, and the calculator (there are two; one for watts and the second for amps) will tell you what wire size you need for a generator.
- Generator Wire Wattage Chart. In the first chart, you will find the wire sizes you need for all generators; from a 500W generator to a 50,000W generator.
- Generator Wire Amps Chart. In the second chart, you will find the wire sizes you need for all generators; from a 10 amp generator to a 200 amps generator.
Note: If you don’t find your answer, you can use the comment section below, give us the wattage or amps of your generator, and we’ll try to help you out.
Let’s start by explaining how the generator wire size is calculated:
How To Calculate Generator Wire Sizes?
The whole point of choosing the correctly sized generator wire is to determine a big enough wire that can handle all the amps. Every AWG wire has a specified ampacity; this is the current (amps) it can safely carry.
If you can figure out the ampacity, you can consult the wire ampacity chart here, and check what size wire you need for your generator.
Figuring out the ampacity start with calculating the generator amp draw. This is already done if you know you have a 50 amp, 100 amp generator, and so on. If you only know the generator’s wattage, you can calculate the amps.
Here is the full step-by-step calculation of how to determine the wire size for a generator:
- Divide the generator’s wattage by the voltage to calculate the amp draw. Amp Draw = Wattage / Voltage. Example: A 10,000-watt generator on a 220V voltage draws 10,000W/220V = 45.5 amps.
- Account for the 80% NEC rule by multiplying the amp draw by 1.25. According to the National Electricity Code (NEC), the maximum load of any circuit breaker is 80% of the rated ampacity. Example: If you have a 50 amp generator, these 50 amps represent 80% (or lower) of the total wire ampacity. That means you need a wire that can handle 25% more amps (1/0.8 = 1.25). This is a safety measure that prevents you from overloading the circuit (overloaded wires can catch on fire).
- When you get the minimum ampacity needed, consult the wire ampacity chart and pick a wire that can handle that ampacity or higher. Example: A 50 amp generator needs a wire with at least 62.5A ampacity. You can’t use an 8 AWG wire because it only has 50A ampacity. You will need to use a 6 AWG wire because it has 65A ampacity; more than 62.5A.
Don’t worry if all this sounds a bit complex. You can use two calculators below that do all this calculating automatically. Further on, you will also find the calculated charts for various generators and the wire sizes needed:
Wire Size Wattage Calculator (Insert Wattage, Get Ampacity)
Here you just insert the size of your generator in watts (Example: 12,000W generator) and the calculator will determine the minimum ampacity a generator wire should have:
Let’s say that you have a 12,000W generator. The calculator will tell you that you need a wire with at least 68.18A ampacity. You just consult the wire ampacity chart and check which wire has more ampacity than that. In this case, the best wire for the 12,000-watt generator is a 4 AWG wire with 85A ampacity.
Note: You can also use multi-strand wires. For example, 10 AWG wire has an ampacity of 35A. Two 10 AWG wires (denoted as 10/2 wire) have a combined ampacity of 70A; this is more than the minimum needed 68.18A for a 12,000W generator). That’s why we can use a 10/2 wire here as well.
The next calculator is for guys who determine the size of their generators in amps (it’s basically the same thing but with amps):
Wire Size Amps Calculator (Insert Amps, Get Ampacity)
Here you just insert the size of your generator in amps (Example: 100 amp generator) and the calculator will determine the minimum ampacity a generator wire should have:
As we can see, if you have a 100 amp generator, you will need a wire with at least 125A ampacity (this accounts for 80% NEC rule). Consulting the wire ampacity chart, you see that 1 AWG wire has a 130A ampacity; this is the correct wire size for a 100 amp generator.
You can play around with these calculators to see how the minimal wire ampacity for a generator changes. We already did all the calculations for you, complete with the generator wire sizing. You can check both of the following charts to check what size generator wire you need:
Wire Size Wattage Chart (For 500W – 20,000W Generators)
| Generator Wattage: | Minimum Ampacity: | Wire Size: |
| 500 Watt | 2.84 Amps | 24 AWG |
| 1,000 Watt | 5.68 Amps | 22 AWG |
| 1,500 Watt | 8.52 Amps | 20 AWG |
| 2,000 Watt | 11.36 Amps | 18 AWG |
| 2,500 Watt | 14.20 Amps | 16 AWG |
| 3,000 Watt | 17.05 Amps | 14 AWG |
| 3,500 Watt | 19.89 Amps | 14 AWG |
| 4,000 Watt | 22.73 Amps | 12 AWG |
| 4,500 Watt | 25.57 Amps | 10 AWG |
| 5,000 Watt | 28.41 Amps | 10 AWG |
| 6,000 Watt | 34.09 Amps | 10 AWG |
| 7,000 Watt | 39.77 Amps | 8 AWG |
| 8,000 Watt | 45.45 Amps | 8 AWG |
| 9,000 Watt | 51.14 Amps | 6 AWG |
| 10,000 Watt | 56.82 Amps | 6 AWG |
| 11,000 Watt | 62.50 Amps | 6 AWG |
| 12,000 Watt | 68.18 Amps | 4 AWG |
| 13,000 Watt | 73.86 Amps | 4 AWG |
| 14,000 Watt | 79.55 Amps | 4 AWG |
| 15,000 Watt | 85.23 Amps | 3 AWG |
| 16,000 Watt | 90.91 Amps | 3 AWG |
| 18,000 Watt | 102.27 Amps | 2 AWG |
| 20,000 Watt | 113.64 Amps | 2 AWG |
| 25,000 Watt | 142.05 Amps | 0 (1/0) AWG |
| 30,000 Watt | 170.45 Amps | 000 (3/0) AWG |
| 35,000 Watt | 198.86 Amps | 000 (3/0) AWG |
| 40,000 Watt | 227.27 Amps | 0000 (4/0) AWG |
| 45,000 Watt | 255.68 Amps | 250 kcmil |
| 50,000 Watt | 284.09 Amps | 300 kcmil |
As you can see, there is quite a range of wires that can be used to wire a generator. Most wires are AWG wires. With the massive 40,000W+ generators, you will have to use even bigger kcmil wires.
Here are the same calculations for generator size in amps:
Wire Size Amps Chart (For 5A – 200A Generators)
| Generator Amps: | Minimum Ampacity: | Wire Size: |
| 5 Amp Generator | 6.25 Amps | 20 AWG |
| 10 Amp Generator | 12.50 Amps | 18 AWG |
| 15 Amp Generator | 18.75 Amps | 14 AWG |
| 20 Amp Generator | 25.00 Amps | 12 AWG |
| 25 Amp Generator | 31.25 Amps | 10 AWG |
| 30 Amp Generator | 37.50 Amps | 8 AWG |
| 35 Amp Generator | 43.75 Amps | 8 AWG |
| 40 Amp Generator | 50.00 Amps | 8 AWG |
| 45 Amp Generator | 56.25 Amps | 6 AWG |
| 50 Amp Generator | 62.50 Amps | 6 AWG |
| 60 Amp Generator | 75.00 Amps | 4 AWG |
| 70 Amp Generator | 87.50 Amps | 3 AWG |
| 80 Amp Generator | 100.00 Amps | 3 AWG |
| 90 Amp Generator | 112.50 Amps | 2 AWG |
| 100 Amp Generator | 125.00 Amps | 1 AWG |
| 125 Amp Generator | 156.25 Amps | 00 (2/0) AWG |
| 150 Amp Generator | 187.50 Amps | 000 (3/0) AWG |
| 175 Amp Generator | 218.75 Amps | 0000 (4/0) AWG |
| 200 Amp Generator | 250.00 Amps | 250 kcmil |
With this amp table, you can figure out what size wire you need for a generator.
If you need some additional help with generator sizing, you can check what size generator you need here. You can also check the list of the quietest generators currently on the market here; with home generators, people are mostly concerned with high noise outputs (which is understandable).
If you have a specific generator in mind, you can use to comments below and we’ll try to help you out with generator wiring.
Thank you.
Table of Contents
FAQs
What size wire should I use for a generator? ›
Generator Wire Size by Circuit Breaker
If the inlet is rated at 50-Amps, you must use wire rated for 50-amps. For example, even if your generator supplies less than 30 amperes, safety and NEC codes still require the use of 10-gauge wire or larger wire for a 30-amp inlet box.
- Calculate the Voltage Drop Index (VDI) using the following formula:
- VDI = AMPS x FEET ÷ (% VOLT DROP x VOLTAGE)
- Determine the appropriate wire size from the chart below.
Minimum ground wire size is #8 copper or insulated #6 aluminum. Since the generator run will be circuit breaker protected at 100A, you can use 100A rated wire.
What size wire do I need for a 14 kW generator? ›I notice that Ziller recommends 4awg wire for my 60amp 14kw install. The proposal I have received from our installer shows they will be using 6awg aluminum. This is a 65 foot run from transfer switch to generator.
Will 8-gauge wire carry 50 amps? ›An 8-gauge wire can handle a current of 50 amps at a temperature of 90-Celsius or 194-Fahrenheit.
Can 6 gauge wire handle 60 amps? ›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. 4 AWG can handle 85 amps; that's more than enough ampacity to adequately wire a 60 amp breaker, even accounting for the 80% breaker rule.
How far can you run 8 gauge wire for 30 amps? ›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.
What size wire do I need for 50 amps? ›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.
What size wire do I need for a 3 phase motor? ›The cable size is equal to the 1.5 times of the full load current of the motor/load. Hence the cable rating formula can be written as, Cable size = 1.5 x Full Load Current.
How Far Will 6 gauge wire carry 50 amps? ›Yes, a 6 gauge wire can definitely handle 50 amps. A 6 gauge wire will handle amperage all the way up to 55. You will find that most appliances use a 50 amp breaker.
What size wire do I need to run 50 amps 100 feet? ›
In most cases, 6 AWG is an almost perfectly-sized wire for a 50 amp breaker. In limited cases, you will probably have to use a larger 4 AWG wire. That's when you have a long circuit and are sending electrical current at some distance (100 feet or more).
What size breaker do I need for a 12000 watt generator? ›It's typical to use a 30-amp breaker for generators up to 8,000 watts and a 50-amp breaker with 8,500- to 15,000-watt generators.
What wire do I use for a 100 amp sub panel? ›The cable must have a wire gauge sufficient to the amperage of the subpanel—a 100-amp subpanel requires #4 copper wires or, more commonly, #2 aluminum wires, for example. (Aluminum is often used for feeder cables because the cost is typically much lower than that of copper wires.)
What size wire do I need to run 100 amp Service 150 feet? ›100 amp service 150 feet away from the sub panel requires #00 AWG wire (also known as 2/0 AWG wire). This wire has a median ampacity of 175 amps; more than enough than the required minimum 162.5 ampacity.
What size wire is needed for a 16KW generator? ›Generac PRYSMIAN 10-16KW Generator Power Composite Installation Cable 3/3 6/1 16/6 ALUMINUM Conductors With PVC Jacket. 1000 Ft.
How many amps is a 10kw generator? ›The best way to size a manual transfer switch is to match it to the largest outlet on your generator. For example, if you see that your generator's largest outlet is rated at 30 amps, you will need to buy a 30-amp transfer switch to get the full power load.
How many amps is #8 wire good for? ›RULES OF THUMB
“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].”
6 Gauge Wire Amps Chart
As you can see, the maximum number of amps a 6 gauge wire can handle is 60 amps. This is the 6 AWG copper wire at 90°C (194°F).
What size wire do I need to run 60 amps 100 feet? ›
In order to use 60 amps, a 4 gauge wire is required.
What size wire do you need for 70 amps? ›Let's dispel the confusion surrounding the question, “What size wire for 70 amp breaker?” According to official recommendations based on breaker rating, the minimum wire size you should use is 4 gauge copper or 2 gauge aluminum.
Can 6 gauge wire handle 70 amps? ›In particular, a 4 AWG copper cable can hold at least 70 amps of electricity before giving up. Meanwhile, a 6 AWG copper wire can only hold up to 55 amps before it falters.
How many watts can 8-gauge wire handle? ›Depending on the voltage, the 8 AWG copper wire can carry anywhere from 480 watts (12V circuit) to 9600 watts (240V circuit). Under the same conditions, the ampacity of the 8 AWG aluminum wire is 40A. Accounting for NEC 80% rule, this means that a 8 AWG aluminum wire can handle up to 32 amps of current.
What wire is needed for 220v 30 amp? ›Any circuit fused for 30 amps must use a minimum of 10 ga copper or 8 ga alu. Longer runs may require an upgrade of wire size.
How far can you run wire before voltage drop? ›...
For 120-volt circuits:
| 14 AWG | 50 feet |
|---|---|
| 12 AWG | 60 feet |
| 10 AWG | 64 feet |
| 8 AWG | 76 feet |
| 6 AWG | 94 feet |
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 size wire do I need to run 40 amps 100 feet? ›That's why we use #6 AWG wire for 40 amp service 100 feet away.
What size wire is needed for 35 amps? ›| Copper | ||
|---|---|---|
| 14 | 15 | 20 |
| 12 | 20 | 25 |
| 10 | 30 | 35 |
| 8 | 40 | 50 |
#10 wire is just fine. The wire going to the outlet from the breaker is probably #10 and is likely to be run longer than the cord will be. Also, 220 volts "divides" the amps between the 2 110 volts hot wires, 12.5 amps per wire. #10 wire is just fine.
How do I know what size cable I need for my engine? ›
Size of Cable for Branch circuit which has Single Motor connection is 125% of Motor Full Load Current Capacity. Example: what is the minimum rating in amperes for Cables supplying 1 No of 5 hp, 415-volt, 3-phase motor at 0.8 Power Factor. Full-load currents for 5 hp = 7Amp. Min Capacity of Cable= (7X125%) =8.75 Amp.
What wire do you use for 3 phase? ›Some three-phase power supplies do use a fourth wire, which is a neutral wire. The two most common configurations of three-phase systems are known as wye and delta. A delta configuration has only three wires, while a wye configuration may have a fourth, neutral, wire.
How many #6 wires can go in a 3/4 conduit? ›| Conduit Size | Conduit Type | 8AWG |
|---|---|---|
| 3/4" | EMT | 6 |
| PVC | 5 | |
| 1" | EMT | 9 |
| PVC | 9 |
The 6 3 copper wire amp rating is typically 55 amps. But heat can also change the 6 3 wire amp rating, for there's a relationship between temperature and the wire's current carrying capacity. For example, a 6 3 wire with ground might have a reduced amperage carrying capacity of 50 amps.
What can I run off a 50 amp breaker? ›A 50-amp breaker can run appliances like ovens, hairdryers, air conditioners, and multiple lights simultaneously while (possibly) still sparing power. The reason for this breaker's capacity is because it can hold up to 12,000 watts running on a 240-volt circuit (50-amps x 240-volts).
What size wire do I need to run 100 amp Service 100 feet? ›What size wire do I need for 100 amps? It will depend on the system voltage and the distance between the feeder and equipment. Our Omnicalculator 100 amps wire size tool indicates that for 100 feet, 110 volts (three-phase), you should consider a 2 AWG cable.
What size wire do I need for 40 amp 240 volt? ›The size wire you need to operate with a 40-amp breaker safely is an 8-AWG wire. It is possible to install a 40-amp circuit breaker on a larger gauge wire, such as a 6-AWG wire, but installing it on a smaller gauge wire will violate the code.
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.
What size wire do I need for 10000 watts? ›The Size Wire for 10000 Watt Heater
As stated above, the proper wire size, adhering to the American Wire Gauge, is determined to be a #6 copper wire.
How many amps does a 8000 generator provide? In general, a 8000 watt generator provides approximately 66.7 amps, in case of 120 volts or 33.3 amps in case of 240 volts.
Can I use a 50 amp breaker with a 30 amp generator? ›
The simple answer to your question, ignoring the many other worthwhile discussions that must be had, is yes. If you install a 50A inlet and buy a 30A generator you can use a suitable cable to plug it in.
Can you run a 100 amp sub panel off a 100 amp main panel? ›Let me try and answer some of your questions. First the panels you are looking at that are rated 100A simply means you can use them for any application up to 100A. You can for example add a 60A breaker to your existing panel and protect the new subpanel with a 100A rating.
How many 30 amp breakers can I put in a 100 amp panel? ›Depending on how the 100- amp panel was manufactured, you can install breakers between 20-24 (minimum) and 30-42 circuits (maximum).
Can you use 6 gauge wire for 100 amp service? ›Before I elaborate further, let me give you the answer you came here for. What wire size is needed for 100 AMP service? For 100 AMP service, you'll need a #4 AWG copper wire or #2 AWG aluminum or copper-clad wire. Make sure to limit your voltage drop to 3% regardless of distance.
What wire size do I need for 200 amp service? ›For a 200 amp service, you'll need: #2/0 copper wire, or. #4/0 aluminum or copper-clad aluminum wire.
What size wire is needed for 125 amps? ›| SERVICE ENTRANCE CONDUCTORS SIZE AND RATING | ||
|---|---|---|
| Service or Feeder Rating | Copper Conductors | Aluminum or Copper-Clad Aluminum |
| 100 Amps | #4 AWG | #2 AWG |
| 125 Amps | #2 AWG | #1/0 AWG |
| 150 Amps | #1 AWG | #2/0 AWG |
Wire Sizes For A 200 Amp Service
To safely use a 200 amp electrical service, you will need to use #4/0 Aluminum, Aluminum Clad Wire, or #2/0 Copper. These are the safest wire sizes because they will allow you to use the full amperage of your electrical service without too high of a voltage drop.
It's typical to use a 30-amp breaker for generators up to 8,000 watts and a 50-amp breaker with 8,500- to 15,000-watt generators.
What size wire do I need for 50 amp? ›50 AMP Wire Size
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.
In most cases, you will need an #8 AWG wire for a 30 amp 240V circuit. The key for 30 amp wire sizing is to account for 2 NEC codes, namely: NEC 220-2 Code. This requires that a conduit wire's maximum load (30 amps) represents 80% of ampacity of that wire.
Do I need a special extension cord for a generator? ›
You simply select a power cord that matches the most powerful outlet on your generator. So, if you have a 50-amp outlet, you'll need a 50-amp power cord. If you have a 20-amp outlet, you'll need a 20-amp cord. Choosing a lower-amp cord will result in wasted power potential and possible damage to your equipment.
What size wire do I need for 10000 watts? ›The Size Wire for 10000 Watt Heater
As stated above, the proper wire size, adhering to the American Wire Gauge, is determined to be a #6 copper wire.
How many amps does a 8000 generator provide? In general, a 8000 watt generator provides approximately 66.7 amps, in case of 120 volts or 33.3 amps in case of 240 volts.
Can I use a 50 amp breaker with a 30 amp generator? ›The simple answer to your question, ignoring the many other worthwhile discussions that must be had, is yes. If you install a 50A inlet and buy a 30A generator you can use a suitable cable to plug it in.
What size wire do I use for 220v 50 amp? ›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 size wire do I need to run 50 amps 200 feet? ›In most cases, 6 AWG is an almost perfectly-sized wire for a 50 amp breaker. In limited cases, you will probably have to use a larger 4 AWG wire. That's when you have a long circuit and are sending electrical current at some distance (100 feet or more).
What size wire is rated for 40 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].”
How far can you run 10 gauge wire for 30 amps? ›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.
What gauge wire is needed for 240V? ›On Average any 240 volt circuit must be a minimum of 14 gauge AWG or larger to meet code requirements. For example a basic 240 volt outlet that draws up to 15 amps would be wired with # 14/2 conductor with ground. This is a North American Standard.
What size wire do I need for a 30 amp service? ›What size wire do I need for a 30 amp 220v circuit? The wire needed must be at least 8-gauge aluminum or 10-gauge copper in size to safely run a 30 amp 220v circuit.
How far can you run an extension cord from a generator? ›
If your extension cord is #16 gauge wire, you can have a cord up to 50 feet. For the same appliance, if your cord is #10 gauge, your maximum length is 250 feet.
Does generator cord length matter? ›The first thing you should consider is if you are using your portable generator for backup power or recreation. That's because it's important to make sure the gauge (thickness of the wire) and length fit your purposes. As a rule of thumb, you should never use an extension cord longer than you absolutely need.
What size extension cord do I need to run a refrigerator on a generator? ›The short answer is that you do not need a special extension cord for a refrigerator and you in fact should not use one. The best size to use in this case is 14 gauge awg and it should be at least 30 feet long.