ASIC miner power requirements: voltage, circuits and breakers

Almost every machine on this site needs a dedicated 240 V circuit,
and the breaker has to be bigger than the arithmetic first suggests. A
miner runs 24 hours a day, which makes it a continuous load, and a continuous load
may only occupy 80 per cent of its breaker. That single rule is what turns a
3,510 W Antminer S21 Pro — 14.6 A at 240 V — into a
20 A two-pole breaker rather than the 15 A one the raw current would
allow.

Below is every machine we stock, grouped by what you have to build
rather than by which coin it mines, with the input voltage its own listing
publishes, what it draws, and the smallest breaker permitted to carry it. If you
want to know which of these is worth buying, that is
the comparison table. This page is only
about whether you can plug it in.

We sell this hardware, take it back when it fails, and the single most common
reason a first machine never earns anything is that it arrived before the circuit
did. Nothing on this page is a substitute for a licensed electrician — it is
the arithmetic to hand them so the conversation takes ten minutes instead of
three visits.

The 80% rule, which sizes every circuit here

The National Electrical Code defines a continuous load as one
that runs for three hours or more (Article 100). An ASIC never stops, so it
is always continuous. NEC 210.20(A) then requires the breaker and the wire to
be rated for at least 125 per cent of that load, which is the same statement
turned inside out: the load may not exceed 80 per cent of the breaker
rating.

So the useful capacity of a circuit is amps × volts × 0.8:

Two things people get wrong with this table. The first is running a 3,400 W
miner on a 20 A 240 V circuit because 3,400 is under 3,840 — correct,
but only if 3,400 W is what the machine actually pulls. The second is
assuming the nameplate figure is that number. It is not: published wall power is a
nominal figure at around 25 °C, real draw moves with ambient temperature
and with the silicon, and tuned firmware moves it a long way. Size for the measured
draw with headroom, not for the brochure. Our own
5,600 W
overclocking supply listing makes the same point from the other direction: a
bigger PSU removes one limit and none of the others, and the circuit is still the
circuit.

Runs on an ordinary 120 V outlet

These are the only machines here you can plug into a normal North American socket without calling anyone. Check the amps column anyway: a 15 A household circuit tops out at 1,440 W continuous and a 20 A one at 1,920 W, and two of these are close enough to that ceiling to matter.

Needs a dedicated 240 V circuit

The bulk of the catalogue. There is no adapter that makes these work on a household outlet - the power supply will not start below its rated range, and even if it did, the wattage is past what any 120 V branch circuit may carry. Budget for an electrician and a two-pole breaker before you budget for the miner.

Needs a 380-415 V industrial feed

Hydro machines built for a datacentre supply, not a building service. These will not run on 240 V at all. If you do not already know what your service voltage is, these are not the machines to find out on.

Needs an industrial three-phase supply

These listings do not itemise an AC input range, but they do say in their own copy that the machine needs a three-phase industrial feed. That is a different question from voltage: a 240 V single-phase branch circuit will not run one no matter how large the breaker is. We are deliberately not printing an amp figure, because the current per line depends on the service voltage and on whether the supply is delta or wye, and these listings state neither. Tell us what your service is and we will work it through before you order.

Powered from a separate DC supply

No AC inlet on the miner itself. What it needs from the wall is entirely a question of which power supply you pair it with.

Input voltage not published - ask before you order

Low-draw machines whose listings do not itemise an AC input range. We are not going to invent one. Every machine in the catalogue drawing more than 1,920 W is in the 240 V group above regardless of what its listing states, because that figure alone rules out any 120 V circuit - these are the ones where it genuinely is an open question. Call and we will read the label off the unit.

Browse every miner in stock → · Compare them on efficiency and running cost →

Why 120 V almost never works

Three separate things have to be true before a machine will run on a normal
North American outlet, and for most of this catalogue none of them are.

The supply has to accept it. A power supply rated 200–240 V
will not start at 120 V. It is not derated, it does not run slowly — it
does nothing. Several listings here say so in the spec table in as many words.

The wattage has to fit. Even a machine rated for 100–240 V
still has to fit inside a 120 V circuit, and the ceiling is 1,440 W on a
15 A circuit and 1,920 W on a 20 A one. This catches the
Avalon Q 90T, which is
the home machine in the range and genuinely accepts 110–240 V — but
at 1,674 W it draws just under 14 A at 120 V, so it needs a
20 A circuit to itself, not the 15 A one most rooms are
wired with. It will trip a shared bedroom circuit. The
Avalon Q against the S19k Pro is
mostly an argument about exactly this.

The circuit has to be dedicated. Continuous 80 per cent
occupancy means there is nothing left for anything else on that breaker. A miner
sharing a circuit with a fridge or a space heater is a nuisance trip waiting for
the compressor to start.

There is one honest workaround and we sell it: the
Loki Kit converts
an S19 or S21 to 110/120 V operation. Read what it actually is before you get
excited — it only works if you also cut the machine’s power in
firmware, to roughly 1,400 W on a 15 A outlet or 1,900 W on a
20 A one. You are buying the ability to run a 3 kW miner at less than
half power. Sometimes that is exactly the right trade and sometimes you should have
bought a machine designed for the voltage you have.

208 V is not 240 V, and the difference costs you a breaker size

Commercial and multi-tenant buildings usually deliver 208 V between phases
rather than 240 V. The machines are rated for it. The circuit is not the same
circuit, and the direction of the difference surprises people: the same
load on a 208 V feed draws more current, not less. Watts are watts,
so lower voltage means higher amps.

A 3,510 W S21 Pro is 14.6 A at 240 V and 16.9 A at 208 V
— enough to push it from a 20 A breaker to a 25 A one. Every table
above carries both columns for that reason. If you are quoting a job from a spec
sheet written for 240 V and your building is 208 V, re-run it.

Cords, inlets and plugs

The wall end is ordinary: 240 V circuits in North America terminate in a
NEMA 6-15 or 6-20 receptacle, or an L6-20 / L6-30 twist-lock where something
must not fall out. Your electrician picks it to match the breaker.

The miner end is the part that surprises people. Bitmain’s APW-series supplies
do not take one fat cable — they take two IEC C13 cords into two C14
inlets, which you can see on the
APW17
supply in the photograph at the top of this page. Two, because a single C13
coupler is rated 10 A under IEC 60320, and even the 15 A cordsets
sold in North America leave no continuous-load headroom on a 3.5 kW machine.
Both have to be plugged in. A miner running on one cord is a fire risk, not a
half-powered miner.

Not every unit uses that pattern — some use the larger C19/C20 pair, and
the machines on this site that take DC from a separate supply use none of it. Cords
are also only included when a listing names them, which is the
store’s standing rule and not a trick. If you need to know which inlet is on the
exact unit before you order cordage,
call us and we will look at it. We also stock
APW9/APW12 supply
cables and a range of
replacement supplies and parts.

How many miners your panel will take

The honest answer is that a licensed electrician works this out with a load
calculation under NEC Article 220, because it depends on everything else in
the building, not on the miners. But the intuition is simple enough to plan
with.

A 200 A residential service has 200 A available on each of two
240 V legs. A 3,510 W S21 Pro on its 20 A two-pole breaker takes
20 A off both legs. Six of them is 120 A of two-pole capacity —
before the house has heated any water, run any air conditioning or cooked
anything. In practice a typical 200 A domestic service supports two or three
of these machines, not six, and the number falls further in summer.

If the power is coming off your own array rather than the utility, the limit stops being the panel and becomes the generation, which is a much harder ceiling: a single 3,510 W machine run around the clock needs roughly 23 kW of solar and 68 kWh of storage. The array and battery each machine here needs has the figure for every one of them.

This is the point at which people start asking about a sub-panel, a service
upgrade, or somewhere else to put the machines. If you are past three units you are
running a small site rather than a home rig, and the economics change with it:
types of mining
farms is about who ends up owning the power problem, and
what is a mining
farm covers the scale where dedicated infrastructure starts paying for
itself.

What we actually see go wrong

These are the failures that come back to us, in the order we see them.

• The machine arrives before the circuit does. It sits in a
  garage for six weeks earning nothing while an electrician is booked. Order the
  circuit first; it has the longer lead time.
• An extension lead. A miner is a continuous 15-amp-class load
  run through a cord rated for intermittent use. The cord gets
  hot, the connector oxidises, and the failure is at the plug rather than in the
  miner.
• One cord in a two-inlet supply. Covered above. It is the
  single most common cabling mistake on Bitmain hardware.
• A 208 V building and a 240 V spec sheet. The breaker
  holds for a week and then starts tripping on the hottest afternoon.
• Voltage sag on a long run. A supply near the bottom of its
  range on a long undersized run will shut down under load and come back, repeatedly.
  The miner looks faulty. It is not.

None of these are miner faults, and all of them look like miner faults for the
first week. If a machine you bought here is behaving like this, the checks worth
running are in
acceptance-testing a miner you just
received — do them while the claim window is still open.

What to ask your electrician

Bring them four numbers and one sentence, and you will get a quote rather than a
survey. The four numbers are in the table above for whichever machine you are
buying.

• The wattage at the wall, and that it is continuous 24/7.
• The voltage the supply requires.
• The breaker size the 80 per cent rule gives.
• The receptacle you want on the end of it.
• And the sentence: “it is a continuous load, so it needs to be sized
  at 125 per cent under 210.20(A).” Any competent electrician knows
  this. Saying it up front tells them you are not describing a hobby computer.

Ask about the heat in the same conversation. Every watt going
in comes back out as heat in that room: a 3,510 W miner is a 3.5 kW
heater that never switches off, which is about three domestic space heaters. And
ask about noise before you commit to a location — most of
these run at 75 dB, which is
not a domestic sound.

Questions buyers ask us about power

Before you order

The circuit is half the problem. The other half is where the heat goes, and for a hydro or immersion machine that is a loop, a radiator and a fluid inventory you buy separately — see ASIC miner cooling: air, hydro and immersion.

Find the machine you want in the tables above, take its voltage, wattage and
breaker size to an electrician, and get the circuit quoted before you pay
for the miner. If the quote changes which machine makes sense, that is the quote
doing its job — a cheaper miner on a circuit you already have beats a better
one you cannot power.

If you are still choosing, the running-cost ranking is at
compare ASIC miners, the specs are explained
in the ASIC miner
buying guide, and the machines that suit a house rather than a shed are in
best mining hardware for
home. For what a full first setup costs beyond the miner itself, see
what you need to
start mining Bitcoin and
five example
builds.

Or ask a person who has wired these up:
+1 (781) 577-0377,
ns@ingmining.com, or the
contact form. Everything in stock is at
all miners, and the supplies, cables and testers are
at miner parts.