Power supply and wiring for an ASIC miner

01How much current a miner draws

Current is power divided by voltage. A Spanish socket gives 230 V, so a 3500 W miner draws 3500 / 230 = 15,2 A. That is not a peak figure. The ASIC holds it for days on end, with no pauses.

Do the sum on the nameplate power, not on an hourly average. Bitmain usually states a tolerance of ±5 per cent, and overclocked firmware pushes consumption up. If you plan to overclock, take the upper bound.

02Cable and breaker

A breaker has to satisfy two conditions at once. It must sit above the working current with margin and below what the cable can carry. The margin matters because a round-the-clock load is nothing like a kettle for five minutes: the breaker warms up and starts tripping on its own. Working rule: keep the working current under 80 per cent of the rating.

Copper, not aluminium. Curve C on the breaker. Next to it a 30 mA residual current device of type A: an ASIC is a switched load and the common type AC copes worse with it.

The line runs from the consumer unit to the miner with nothing in between. The socket is not shared with other appliances. Past fifteen metres, go one size up on the cable because of voltage drop.

03One phase or three

Most miners run on a single phase. Bitmain accepts 200 to 277 volts AC depending on the model, and a machine like that has nowhere to connect three phases.

The exception is the hydro range. Those are built for three phase supply at 380 to 415 volts and will not plug into a domestic socket at all. They need a three phase supply, their own distribution board and a coolant loop, so nobody fits them at home.

Three phases also come in without hydro, once there are several single phase miners. One 3,5 kW machine eats almost everything a domestic 16 or 20 A supply provides, and at two machines a single phase supply is finished. Then you bring in a three phase supply, a distribution board, and spread the miners across phases keeping the load roughly even.

Phase imbalance is not an abstraction. With three miners on one phase and none on the other two, the main breaker trips on that phase and the meter can start reading wrong. Work out the load phase by phase, not as a total.

04Power connectors

Bitmain uses four kinds of inlet. Older models took power through several C13 or C14 connectors. The more powerful ones moved to C19 and C20, rated for 16 A. Current machines use Bitmain connectors of their own: P13 on single phase models and P33 on three phase ones.

P13 and P33 are not interchangeable. The P13 has four contacts for a single phase supply, the P33 has six for three phases. They will not physically mate the wrong way, but a cable is ordered for one specific type, so confirm yours before buying.

Pick a cable rated for 16 A and no longer than the site needs. A desktop computer lead will not do here: it is rated for 10 A and gets hot.

Power strips and household extension leads have no place next to a miner. They are built for short bursts, not for 15 A around the clock, and they are the first thing to start melting.

05What the network side needs

The miner connects by cable only. Bitmain has never put Wi-Fi in any model.

• A router with a free RJ45 port and DHCP switched on
• Twisted pair crimped at both ends, as long as the site needs
• A permanent internet connection, the machine runs around the clock
• A computer on the same network to find the miner and open its web panel

The miner survives an internet outage. It keeps calculating and queues the results, but shares only reach the pool once the link is back. Long outages show up in the earnings.

06Common mistakes

1. A breaker rated the same as the working current. Within hours it starts tripping by itself and you go looking for a fault in the miner.
2. Aluminium wiring in an old building. It was never meant for 15 A continuous and the socket contacts burn.
3. A line shared with appliances. The washing machine plus the miner trip the breaker at the worst moment.
4. No residual current device. With an insulation fault inside the power supply this stops being a question of convenience.
5. A five way power strip. It runs hotter than the miner itself.

07Frequent questions