Three Phase Power
Three phase power is a supply of three phases instead of one. For mining it is the way to get more kilowatts and to spread the load.
What three phase power is
In a household supply there are about 230 volts between a phase and neutral and about 400 between two phases. A three phase feed gives three such lines, and total power triples with the same breakers. The asics themselves stay single phase: each one plugs in between its own phase and neutral.
It is easiest to count per phase. A 32 A breaker at 230 volts gives about 7.4 kW, which is two asics of 3500 W and no room for a third. Three such phases give about 22 kW in total, and that is six S21 asics with a little margin.
A single phase feed in Spain is capped at 14.49 kW, and household steps of contracted power start at 3.45 kW. Hence the boundary: four asics are already the limit of one phase even on a generous contract, and beyond that only three phases will do, which is a conversation with your energy supplier rather than a trip for an extension cord.
The main requirement during installation is balance. The load gets spread evenly across the phases, otherwise the imbalance wanders down the neutral conductor and heats it. Electricians design this, and we do not advise building such a feed yourself: the price of a mistake here is a fire rather than lost hashrate.
Quick reference table
| Voltage | about 230 V per phase, about 400 V between phases |
| One 32 A phase | about 7.4 kW, two asics of 3500 W |
| Three phases of 32 A | about 22 kW, six S21 asics |
| Limit of one phase in Spain | 14.49 kW |
| Mandatory condition | load balanced across the phases |
What to do first if there will be more than two asics
Start by finding out what feed the room has and how much contracted power they are willing to give you. Only then count asics: the reverse order leads to equipment with nowhere to plug it in.
Then comes distribution. Two asics per phase on a 32 A breaker, every line on its own cable of the right cross section, a PDU rated for heavy load. A 32 A strip with eight sockets holds those same two asics, since the number of sockets changes nothing here.
And leave margin. Continuous load is a hard duty, breakers and cables cannot be sized to the edge, and the weakest joint in the circuit is always the one that heats: a single contact on a power connector carries 8 to 9 amps.
An example calculation
A room with three phases of 32 A is about 22 kW. Six S21 asics at 3500 W each draw 21 kW and fit two per phase. The heat is exactly the same 21 kW, so the extraction gets sized for that flow. The electricity bill at a rate of 0.135 euros comes to about 2040 euros a month, and that is a figure to know before shipping.
Related terms
Where to go next on the site
Hardware
- Antminer S21 tool
- ASIC Miner knowledge base
Numbers
Questions and answers
Does an ASIC need a three phase power supply
No, asics are single phase. Three phases are for the feed into the room, and each one connects between its own phase and neutral.
How many asics fit on a three phase 32 A feed
About six asics of 3500 W, two per phase. The exact number depends on the model and on whatever else hangs on those lines.
Can you get by on one phase
Up to two asics of 3500 W easily, and up to four on a suitable contract. Beyond that a single phase feed runs into 14.49 kW as a physical wall.
What happens when the phases are unbalanced
Load on the neutral conductor and heat in it, and in the worst case protection tripping and voltage sag. Spreading asics evenly across the phases is a requirement rather than fussiness.
How the terms connect
Every link in the chain is clickable. Orange marks where you are now.
Looking for an ASIC miner
The catalog holds 212 models. You can compare them by hashrate and by joules per terahash, then plug your own rate into the calculator and see what stays in your pocket.
Page written and checked by Denys Klimchuk. Updated .