Ever wonder how many GPU mining rigs you can plug in at home before flipping a circuit breaker? Calculating it is pretty straightforward. First, all the calculations here are for a 120 volt circuit, not a 240 volt circuit. 120 volt circuits power just about everything in your home with the exception of an electric dryer, oven, or HVAC system. Those require 240 volts.

Safety first: don’t burn down the house

Mining cryptocurrency will definitely be unprofitable if you burn your home down in the process. Everything we’re talking about below assumes that the wiring in your home is up-to-code. If you’re in doubt about the electricity in your home or apartment don’t guess. While a blown circuit in the breaker box should be the result of putting too high of a draw on a circuit, an electrical fire is not out of the question. Be safe.

Total capacity of 120 volt residential electrical circuit

U.S. homes run 120 volts. To calculate the total wattage available you multiply volts by the circuit’s amp capacity. The first thing that you will want to do is figure out if the circuit you’re wanting to use is a 15 amp or 20 amp circuit. To find out, take a trip out to your breaker box and identify the circuit you’ll be using. Then, look at the circuit breaker and see if it has a 15 or a 20 on it (which correlates to a 15 amp or 20 amp circuit).

  • 15 amps x 120 volts = 1,800 watts
  • 20 amps x 120 volts = 2,400 watts

Capacity ≠ recommended sustained wattage

Just because there’s 1,800 watts available on a 15 amp circuit (or 2,400 watts available on a 20 amp circuit) doesn’t mean that’s our ceiling. A circuit can only handle sustained usage of 80% of it’s capacity. That means we’ve got less power to work with. Here’s the math:

  • 15 amps x 120 volts x 80% = 1,440 watts
  • 20 amps x 120 volts x 80% = 1,920 watts

How much electricity does a mining rig use?

The amount of electricity a mining rig uses is based on the components used to build it. Measuring the actual power draw when mining at the wall with a meter is the most accurate number you’ll come by. If you do have an electric meter and observed a 820 watt draw while mining, you know everything you need to know. **

A mining rig drawing 820 watts could go on either a 15 amp circuit or 20 amp circuit with power to spare. Of course, don’t forget about what else is plugged into the same circuit. To make sure the circuit can handle adding a miner to it, get a good measure off everything else that’s consuming power. Add all of the watts together and be sure that they’re beneath the 1,440 watts for a 15 amp circuit or 1,920 watts for a 20 amp circuit.

Calculating mining rig power without a meter

If you have a mining rig, but don’t have an electric meter, you can still get a pretty close estimate. On every mining rig the GPUs are responsible for the lion’s share of power consumption. The rest of the entire setup, including the motherboard, drive, CPU and cooling fans draw between 30 and 90 watts.*

The mining software you’re using may report how many watts each GPU is consuming (EWBF does this, for instance). If not, you can turn to a program like GPU-Z to get a read off each video card while mining.**

If your wattage measurement on a 6 GPU mining rig come back at a total of 810 watts, adding 90 watts for the rest of the setup brings the total to 900 watts.

That means you could get two of these 6 GPU rigs (2 x 900 = 1,800 watts) on a single 20 amp circuit (1,920 watt capacity) as long as there wasn’t anything else plugged into it. It wouldn’t be advised to do so with a 15 amp circuit, however. An 1,800 watt draw is far north of the sustained 1,440 watt capacity a 15 amp circuit can provide.

Estimating mining rig power needs

If you’re doing these calculations in preparation for your mining rig build you’ll need to estimate as opposed to measure your need.

As stated above, for everything with the exception of thee video cards, plan on 90 watts being used. Next, calculate the draw of each video card on the mining rig by the estimated wattage below. Finally, add all the numbers together.

GPUPower Consumption
Nvidia GTX 1050 Ti75 W
Nvidia GTX 106090 W
Nvidia GTX 1070130 W
Nvidia GTX 1070 Ti135 W
Nvidia GTX 1080150 W
Nvidia GTX 1080 Ti200 W
AMD RX 470 4 GB140 W
AMD RX 480 8 GB150 W
AMD RX 570 4 GB140 W
AMD RX 580 8 GB150 W

Using everything we’ve learned, we know that a Frankenstein mining rig with one GTX 1070s, three GTX 1050 Ti and one RX 570s would draw:

  • 130 watts + (3 x 75 watts) + 140 watts + 90 watts = 585 watts

If we had somehow found ourselves in possession of two such Frankenstein rigs, we could put them both on a single 15 amp circuit and have some power to spare. Of course, estimates are just that. When you actually get your miners up and running get an accurate reading.

* That’s assuming you’re going with a true mining rig build (meaning low power consumption). If you’ve opted for more than 4 GB of RAM and/or a high performance CPU, the power draw will be higher.

** Different algorithms and under-volting/overclocking schemes consume varying amounts of power. Be sure to get the highest usage numbers you’re expecting to subject the miner to.

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