Disclaimer: Electrical work can be very dangerous! I did this with nothing more than my wits and a few books on electricity. Only do this project if you are familiar with electrical safety! I take no responsibility for any electrical shocks, fire, or damaged equipment. 30 amps of 220v power is enough to cause serious injury and even death. That being said, I’ve run two of these at maximum capacity for the better part of year with no problems.
Bitcoin mining is very power intensive. As the power of mining equipment increases, hobby miners are running out of household electrical capacity. I am going to show you how to easily gain access to thousands of watts of power in the average American household.
I’ve selected the dryer circuit available in most American houses for a number of reasons:
1. Dryer circuits in America are 30amp at 220v. This is enough capacity to run 6600 watts worth of equipment! That is 4x as much power available than the standard 15amp 110v circuit commonly used for household outlets.
2. The dryer circuit in a house always ends up at a preintalled outlet. This is in contrast to other dedicated 220v circuits often found in a house such as an oven, water heater, or air conditioner. These are usually directly wired to the house (no outlet).
3. The dryer outlet is usually in an out of the way location that works well for mining, such as a garage or laundry room.
We are basically going to build a tritap extention cord. On one end is a plug that goes into the dryer wall outlet. On the other end are two sockets that accept 220v plugs. Here is a picture of the final product:
https://i.imgur.com/sJaQUcM.jpgTools Needed:
Wire Stripper
Wire Cutters
Screwdriver
Small Pliers
Hardware Needed:
Dryer replacement cord
12/2 Romex wire (two hot insulated wires with one bare ground wire)
Handy Box x2
220v Standard Outlet x2
Square Junction Box x1
Wire twist caps x4 (I used a water resistant variety with electrical grease as I was using mine in a laundry room)
Step One: Prep the dryer cord
Note: Dryer replacement cords come in two varieties. There are three prong and four prong dryer cords. 3 prong cords are more commonly found in older homes. Newer homes are almost exclusively 4 prong cords. The 4th prong is a neutral wire that allows for simultaneous 220v and 110v power to come through the same cord. I did this project on a 4 prong cord. Since we won’t need this 4th neutral wire, I’ve simply capped it off. You can see this in the picture above as the single white wire going in to a blue cap.
Dryer power cords end in a loop terminal at each wire for installation in to a dryer's power terminal. We wont be using these so cut them off and strip about half an inch of insulation off the end of each of the two hot leads (black and red) and the ground wire (green). For the white wire, DO cut of the loop terminal, but DO NOT strip the wire.
Step Two: Wire the outlet boxes
First, take your 12 gauge romex wire and cut two 1 foot sections and strip half an inch off both ends of the cable.
Second, wire up the outlets. Attach the bare wire (ground) to the green screw. Attach the white wire to the terminal screw on the same side as the ground. Attach the black wire to other side. A small pair of pliers will needed to wrap the wire around the screw terminals.
Third, install the outlet into the handybox. Be sure to knock out one of the holes and thread the 1 foot section of cable through the hole. Install a faceplate for safety.
Now you should have two outlets wired up and ready to be connected to the dryer’s cables.
https://i.imgur.com/rix6hr4.jpghttps://i.imgur.com/5r7XSSr.jpg Step Three: Wire the Junction box
First, punch out 3 holes from the square junction box and insert the wire ends from the dryer plug and the two outlet boxes.
Important: if you are using a 4 prong dryer cord like I am, now is a good time to cap off the WHITE wire from the dryer plug.
Second, connect the two bare ground wires from the outlets and the one green ground wire from the dryer plug.
Third, connect the two white wires from the outlets to the one red wire from the dryer plug.
Fourth, connect the two black wires from the outlets to the black wire from the dryer plug.
There should be no more loose wires. All wires should be capped off at this point. And things should look like this:
https://i.imgur.com/Z3dXGDP.jpgStuff everything down carefully and install the faceplate.
You’re done! You can now power 6600 watts worth of mining equipment of a single, seldom used household outlet!
Optional: install sections of conduit between the outlets and the junction box and a rubber O ring from where the dryer cord enters the junction box. This will prevent rubbing from sharp edges potentially damaging the wire insulation and causing a dangerous short. This would make this project more “to code”.
Total Cost: Approx $50, depending on how much romex wire and tools you happen to have on hand.
Safety Tip for those unsure of their work:
When trying the device for the first time, switch off the breaker at the breaker box and then plug in the cord. Then plug in a device that turns on when given power. I used a power supply with a shorted on switch. Then go back to your breaker box and flip the breaker to on. If everything is good, your device should turn on. If there is a problem, it won't, and you should turn off the breaker before touching anything.
Important Note on Load Balance:
The dryer cord will provide 30amps at 220v. The outlets and romex wire are only rated for 20amps at 220v. This means you can safely run up to 4400 watts on a single outlet. I chose to limit usage to 3300 watts (15 amps) on each outlet. The main thing to keep in mind is total power draw should not exceed 6600 watts between both outlets, and each outlet should be kept under 4400 watts.
Hope this was helpful! Happy mining!
I am considering having these professionally manufactured for sale. I’ve researched this already and I can sell these cheaper than it takes to DIY from a hardware store. If there is enough interest, I’ll put in an order for them. Let me know!
I also posted this on my mining blog,
2BitHasher.comIf you found this useful, you can blow some dust my way at 157TSAgdEPdoRvAB1AxpcgHPTV3eacrN5i
