The maximum amount of Current (Amps) that a 2000 watt inverter is capable of drawing from the battery will mainly depend on 2 factors:

- The conversion efficiency of the inverter
- The voltage rating of the battery bank

And in order to size the wires and the fuse (or circuit breaker) properly you will need to calculate it.

In this article, I’ll provide a simple formula that will allow you to calculate this Max. Amp draw, and I’ll then discuss the size of the wires and over-current protection device that you need for your 2000 Watt inverter.

## How many amps does a 2000 watt inverter draw?

**In general, if your 2000 Watt inverter is running on a 12V battery bank, it could draw as much as 240 Amps of current. If your battery bank is rated at 24 Volts, the 2000W inverter could draw up to 120 Amps of current.**

**If the battery bank is rated at 48V, the amp draw would not exceed 60 Amps.**

However, this is assuming the 2000W inverter converts power from DC to AC at an efficiency of about 85%. Inverters with higher conversion efficiency (90-95%) would draw fewer amps and less efficient inverters (75-80%) would draw more amps.

You can use the following formula to estimate the maximum amp draw of your 2000 Watt inverter:

**Maximum Amp Draw (Amps) = (2000 Watts ÷ Inverter’s Efficiency (%)) ÷ Lowest Battery Voltage (V)**

For example, let’s say we’re using this 2000W Pure Sine Wave inverter from Renogy. And let’s also assume that this inverter is going to run on a **12V battery bank**.

If we look at the specs of this inverter, we can see that the manufacturer claims that the inverter has a **conversion efficiency of 90%** or more.

Now, the inverter is going to run on a 12V battery, however, the actual voltage of the battery bank can go below 12 Volts depending on its State Of Charge (SOC).

If our 2000 Watt inverter needs to, it will put out 2000 Watts of power right up until the battery is cut-off due to low voltage. But right before the battery bank is disconnected, the amount of current (Amps) that our inverter draws from the battery bank will be at its maximum.

So, in order to calculate the Max. Amp Draw, we’ll need to use the lowest voltage at which the battery bank can still supply power to the inverter.

As a rule of thumb:

- If the
**battery bank is rated at 12V**, the**Lowest Battery Voltage**before cut-off is**10 Volts**. - If the
**battery bank is rated at 24V**, the**Lowest Battery Voltage**before cut-off is**20 Volts**. - If the
**battery bank is rated at 48V**, the**Lowest Battery Voltage**before cut-off is**40 Volts**.

Since our battery bank is rated at 12V, the Maximum Amp Draw is going to happen at 10 Volts. Let’s use our formula:

**Maximum Amp Draw (Amps) = (2000 Watts ÷ Inverter’s Efficiency (%)) ÷ Lowest Battery Voltage (V)**

**Maximum Amp Draw (Amps) = (2000 Watts ÷ 90%) ÷ 10 V**

**Maximum Amp Draw (Amps) = (2000 Watts ÷ 0.9) ÷ 10 V**

**Maximum Amp Draw (Amps) = (2222 Watts) ÷ 10 V**

**Maximum Amp Draw (Amps) = 222.2 Amps**

Now, let’s say for example, that we’re using a 2000W inverter that has the same efficiency (90%), but which runs on a 24V battery bank instead.

The Maximum Amp Draw to expect from our inverter is:

**Maximum Amp Draw (Amps) = (2000 Watts ÷ Inverter’s Efficiency (%)) ÷ Lowest Battery Voltage (V)**

**Maximum Amp Draw (Amps) = (2000 Watts ÷ 90%) ÷ 20 V**

**Maximum Amp Draw (Amps) = (2000 Watts ÷ 0.9) ÷ 20 V**

**Maximum Amp Draw (Amps) = (2222 Watts) ÷ 20 V**

**Maximum Amp Draw (Amps) = 111.1 Amps**

Now that we know how much current a 2000W inverter is capable of pulling from the battery bank, we can use that to determine the size of wires and fuse or circuit breaker that we need.

## What gauge wire for 2000 watt inverter?

**In general, if your 2000 Watt inverter is running on a 24V battery, you would need 1/0 AWG copper wires or bigger. If the battery bank is rated at 48V, you would need 3AWG copper wires or bigger.**

If you’re planning on running the 2000W inverter on a 12V battery bank, you should probably consider a 24V or a 48V system instead. Let me explain.

As shown previously, a 2000 Watt inverter running on a 12V battery, can draw up to 240 Amps depending on its efficiency, which is a huge amount of current.

**The U.S National Electrical Code (NEC Article 706.30) states that the ampacity of the wire should not be less than 125% of the Maximum Current (Amps) that will be flowing through the wire.**

For example, let’s say our 2000 Watt inverter is 90% efficient and will be running on a 12V battery bank.

In the previous section, we’ve determined that in such a setup, our inverter can draw up to 222.2 Amps of current. Following the NEC (Article 706.30), the ampacity of the wire that we need is determined as such:

**Wire Ampacity (Amps) **should not be less than** Max. Amp Draw (Amps) x 125%**

**Wire Ampacity (Amps) **should not be less than** 222.2 Amps x 125%**

**Wire Ampacity (Amps) **should not be less than** 222.2 Amps x 1.25**

**Wire Ampacity (Amps) **should not be less than** 277.7 Amps**

Now, let’s take a look at the ampacities of pure Copper wires provided in the following table (NEC table 310.16):

Copper Wire Size (AWG or kcmil) |
75°C(167°F):
Types RHW, THHW, THW, THWN, XHHW, XHWN, USE, ZW |

14 AWG | 20 A |

12 AWG | 25 A |

10 AWG | 35 A |

8 AWG | 50 A |

6 AWG | 65 A |

4 AWG | 85 A |

3 AWG | 100 A |

2 AWG | 115 A |

1 AWG | 130 A |

1/0 AWG | 150 A |

2/0 AWG | 175 A |

3/0 AWG | 200 A |

4/0 AWG | 230 A |

250 | 255 A |

300 | 285 A |

350 | 310 A |

400 | 335 A |

You can see that in order to comply with the safety code, we would need to use a copper wire with a cross-sectional area of 300 kcmil (kilo-Circular-Mils) or bigger. Wires of this size are hard to come by and are extremely expensive.

**If instead, you run the 2000W inverter on a 24V battery bank, you would only need 1/0 AWG copper wires. If the inverter runs on a 48V battery bank, you would only need 3 AWG copper wires.**

**If you already have a 2000W inverter that is rated for 12VDC, you could use 4/0 AWG copper wires, as long as you set the battery’s low voltage cut-off point to about 12.1 Volts (as opposed to 10 Volts).**

If the inverter is programmable, you’ll be able to do this by configuring the Low Voltage Disconnect (LVD). If the inverter is not programmable, you can use devices such as Victron’s BatteryProtect.

**By doing this, the battery will not be allowed to go below 50% State Of charge (SOC) if it’s a Lead-Acid battery, or below 10% SOC if it’s a Lithium battery. But in both cases, this will limit the maximum current intake of the 2000W inverter to about 185 Amps, which will allow you to use 4/0 AWG copper wires.**

However, there are other variables to consider here, such as maximum room temperature and the distance between the inverter and the battery bank.

To size the wires correctly, I recommend using our **inverter wire size calculator**. Below the calculator, you’ll also find some examples and a detailed guide on sizing the wires between the battery bank and the inverter.

In any case, once you determine what size wire you need for your 2000 Watt inverter, you’ll also need to size a fuse or a circuit breaker to protect your wires and equipment.

## What size fuse (or circuit breaker) for 2000 watt inverter?

An over-current protection device (OCPD) such as a fuse or circuit breaker, will be placed on the positive side of the battery bank and will protect your wires and equipment from overheating and potentially catching fire.

Fuses and circuit breakers are rated in Amps, and the Amp rating of the fuse or circuit breaker you use with your 2000W inverter should not be less than 125% of the maximum amp draw of the inverter, but should not be greater than the ampacity of the wires between the inverter and the battery bank.

**Generally, if your 2000 Watt inverter is running on a 24V battery bank, you would need a 150 Amp fuse or circuit breaker. If your 2000W inverter is running on a 48V battery bank, the fuse or circuit breaker should be rated at 70-80 Amps.**

**If your 2000 Watt inverter is rated for 12VDC, you could use a 225 Amp fuse or circuit breaker, but only if the battery’s low voltage cut-off point is set to 12 Volts (as opposed to 10 Volts).**

**To size the over-current protection device properly, simply multiply the maximum amp draw of the 2000W inverter by a factor of 1.25, and find the next bigger fuse or breaker amp rating.**

For example, let’s assume our 2000 Watt inverter is 90% efficient and will be running on a 24V battery bank.

In the first section of this article, we’ve determined that with these specs, the 2000W inverter could draw as much as 111.1 Amps:

**Maximum Amp Draw (Amps) = (2000 Watts ÷ Inverter’s Efficiency (%)) ÷ Lowest Battery Voltage (V)**

**Maximum Amp Draw (Amps) = (2000 Watts ÷ 90%) ÷ 20 V**

**Maximum Amp Draw (Amps) = (2000 Watts ÷ 0.9) ÷ 20 V**

**Maximum Amp Draw (Amps) = (2222 Watts) ÷ 20 V**

**Maximum Amp Draw (Amps) = 111.1 Amps**

Let’s multiply our Max. Amp Draw by 1.25 to determine the required fuse or circuit breaker amp rating:

**Amp rating of the Fuse/Circuit breaker (Amps) = Maximum Amp Draw (Amps) x 1.25**

**Amp rating of the Fuse/Circuit breaker (Amps) = 111.1 Amps x 1.25**

**Amp rating of the Fuse/Circuit breaker (Amps) = 138.8 Amps**

There are no fuses or circuit breakers rated at exactly 138.8 Amps. However, all we have to do is find the next larger Standard Amp Rating.

The Standard Amp Ratings of Over-Current Protection Devices are **10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000 5000, and 6000 Amps.**

Provided we’re using 1/0 AWG copper wires or bigger, we could use a 150-Amp fuse such as this one, or a 150 Amp circuit breaker such as this one.

Why do inverter manufacturers mak 12 v 2000 watt inverters if the wire and fuse or CB requirement is beyond reality?

That is where I am stuck at the moment.

I have 1/O AND 2/O battery cable, 2 -12 v batteries and a 2000 watt inverter. What can I do?

Hey Al,

For safety purposes, the cables and overcurrent protection devices should be sizes as explained above.

However, although I don’t recommend doing this, if your load does not actually require 2000 Watts of power continuously, you could use the 2/0 cables until you find a more proper and safer setup, with the condition that you frequently check the condition of the cables to make sure they’re not getting too hot.

A better solution, if possible, would be to reconfigure your batteries to a 24V battery bank, and get a 24V 2000W inverter instead.

Hope this helps.