Circuit Breaker and RCD
A circuit breaker cuts the line on overload and short circuit, while an RCD cuts it when current leaks. These are different jobs, and one does not replace the other.
How a circuit breaker differs from an RCD
A circuit breaker watches the current in the line. If the current stays above its rating for long or jumps instantly on a short, it opens the circuit. Its job is to save the cable from heating rather than to save a person.
An RCD watches the difference between the current coming in and the current going out. Once a difference appears, part of the current has gone sideways: through insulation, through a case, through a person. A standard 30 mA RCD cuts the line before the leakage turns dangerous. Overload it does not see at all.
There is also the RCBO, both devices in one housing. It saves room in the panel, and when it trips it is not always clear what happened: overload or leakage. A separate pair is easier to diagnose.
The main rule on ratings: the circuit breaker is picked to suit the cable rather than the load. A 32 A breaker on a thin cable will simply let the cable heat up to an unpleasant state without tripping once.
Quick reference table
| Circuit breaker | overload and short circuit, protects the cable |
| RCD | current leakage, protects the person |
| Typical RCD rating | 30 mA |
| RCBO | both in one, harder to diagnose |
| Rating rule | the breaker suits the cable, not the load |
What mining adds to this
Count the load as constant. A miner runs around the clock at almost unchanging power, so a line does not get loaded right up to its rating: the usual guide is about 80 percent of it.
Spread the asics across lines. Power supplies each give a small leakage, and on a shared RCD their leakages add up: four asics on one line can trip it with nothing broken at all.
Do not raise the breaker rating to stop it tripping. The breaker is not the reason for the outage; it is a message that the line cannot carry the load.
Wiring in the panel is an electrician's work. A mistake here costs neither money nor hashrate, and this is not the place to learn on your own apartment.
An example of the math
A single phase service in Spain gives up to 14.49 kW. One phase with a 32 A breaker at 230 V is about 7.4 kW, so two asics at 3.5 kW each will already take up almost all of it. The guide of 80 percent means the second one does not belong on this same line and deserves a line of its own.
Related terms
Where to go next on the site
Hardware
- ASIC Miner knowledge base
- Antminer S21 tool
Numbers
Questions and answers
Why does the RCD trip with no visible cause
Often it is the sum of leakages from several power supplies on one line. Spread the asics across different lines and see whether it happens again.
Can you get by with a circuit breaker alone
It will protect the cable, not the person. Leakage is seen only by an RCD.
Which to choose, an RCBO or a pair
In a cramped panel the RCBO is handier. If there is room, the separate pair is clearer when you pick trips apart.
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 .