A high-current actuator does not care how neat the wiring diagram looks. If the relay, driver, fuse, wire, or power supply cannot handle the actuator current, the system will fail. Size the electrical path around the actuator’s real current draw, not just the voltage printed on the label.
"The switch tells the relay what to do. The relay carries the load. And the fuse goes at the source — not next to the actuator. Get those three things right and most high-current actuator wiring problems disappear."
What is a high-current actuator relay?
<<A high-current actuator relay switches power to a DC linear actuator without forcing the small control switch to carry motor current. The switch tells the relay what to do. The relay or driver carries the load.
What is the simple explanation?
A relay works like a remote-controlled heavy switch. Your button handles a small signal, and the relay handles the actuator power.
Use the formula below to estimate electrical power.
Watts = volts × amps
What should the calculator inputs be?
Use this as a first-pass sizing tool. Then confirm the final choice against the actual FIRGELLI product page, the wiring diagram, and your real mounting geometry.
How do you use this calculator?
- Enter the real project values, not guesses from a different mechanism.
- Use measured current, load, stroke, voltage, or signal values where you can.
- Add margin for real brackets, wiring, friction, and installation conditions.
- Click Calculate to see your result.
How should you wire high-current actuator control?
Keep the high-current path short and simple. Put the fuse close to the battery or power supply, then feed the relay or motor driver, then the actuator.
Do not use a tiny panel switch as the main current path unless its rating truly exceeds the actuator current. The switch should normally trigger the relay, not carry the motor load.
What is a simple example?
A 12V actuator pulls 10A running and may see 25A peak. Running power = 12 × 10 = 120W. Peak load = 12 × 25 = 300W.
With 1.25x supply margin, target supply current = 25 × 1.25 = 31.3A. That points toward a 12V supply and control hardware sized above the peak current, not just the running current.
Recommended FIRGELLI setup
Which FIRGELLI products fit this job?
Choose control hardware from actuator current, not from the shape of the switch.
High Current DC Motor Drive
Use this when the actuator current needs a dedicated high-current DC motor driver instead of a small switch carrying the load.
View High Current DC Motor Drive
12V SPDT Relay 20A
Use SPDT relays when you are building relay logic for actuator direction control and the current rating fits the job.
View 12V SPDT Relay
12V DPDT Relay
Use a DPDT relay when you need polarity reversal in a compact relay setup and the current rating matches the actuator.
View 12V DPDT RelayFor simple manual control, use a verified DPDT toggle switch only when its rating fits the actuator. For full actuator selection, start with the linear actuators collection.
What usually goes wrong with high-current actuator wiring?
- Switch carrying motor current. A small panel switch rated for signal current is used as the main current path. It welds, melts, or arcs under actuator load. Fix: use the switch to trigger a relay or driver sized for the actuator current.
- Fuse placed near the actuator instead of the source. A short in the long wire run between battery and actuator is unprotected. Fix: put the fuse close to the battery or power supply.
- Wire sized from running current, not peak. The wire handles normal load but overheats on stall or startup surge. Fix: size wire and protection around peak or stall current, then verify voltage drop over the run length.
- Power supply sized at running current with no margin. The supply browns out under startup or stall current and the actuator stalls or resets the supply. Fix: target supply current at peak × 1.25 to 1.5.
- Long wire runs with no voltage-drop check. Actuator slows down and draws more current at the actuator end. Fix: shorten the run or step up wire gauge.
How should you test the wiring before trusting it?
- Measure real running current. Run the actuator under the actual load with a clamp meter on the supply lead. Compare against the product page rating.
- Measure peak or stall current. Stall the actuator briefly against a hard stop (or near end-of-stroke) and capture the peak. That is the number your wire, fuse, and driver need to survive.
- Check voltage at the actuator under load. Measure voltage at the actuator leads while running. If it drops more than about 10% below supply voltage, the wire is undersized or the run is too long.
- Cycle under real load, not bench-no-load. Run the actuator through full strokes with the actual load for at least 10–20 cycles. Check relay, driver, and wire temperature after.
- Confirm fuse holds normal current and clears fault current. The fuse should not blow on inrush, but it should clear on a deliberate short at the actuator end (test with a sacrificial setup).
Where does this matter most?
- Marine hatches and lifts. Battery-fed 12V/24V systems with long wire runs from the battery bank to the actuator. Voltage drop and corrosion-rated fuse placement matter.
- RV slide-outs and beds. High peak current under load with shared 12V house circuits. Relay or driver protects the control switch on the wall panel.
- Automotive applications (hood, trunk, tailgate, active aero). 12V battery source, vibration, and heat. Fuse near the battery, wire sized for the under-hood environment.
- Industrial dampers, valves, and panel doors. 24V DC supplies with PLC or relay logic. The PLC output triggers the relay or driver, not the actuator current directly.
