Vertical M10 float switch for water and liquid level control: as the level rises or falls, the float slides along the stem and the magnet inside it opens or closes a reed contact. The output is a simple dry contact that needs no power: read it directly with Arduino, ESP32 or a PLC, or use it to drive a relay that controls pumps, solenoid valves and alarms on tanks and cisterns.
Key features
- Dry reed contact: works with no power supply and no electronics
- Reversible logic: remove the clip and flip the float to change the contact from normally open to normally closed
- Polypropylene (PP) body and float
- M10 thread with nut for mounting through the tank wall
- Two pre-stripped wires, no polarity
Technical specifications
- Type: vertical float switch with reed contact
- Max switching power: 10 W
- Max switching current: 0.5 A
- Max switching voltage: 100 V
- Contact breakdown voltage: 220 V
- Contact resistance: max 100 mΩ
- Operating temperature: -10 °C to +85 °C
- Material: polypropylene (PP)
- Thread: M10, with nut
- Overall length: about 58 mm (wires excluded)
Wiring
| Wire | Arduino / ESP32 | Notes |
|---|
| Wire 1 | Digital pin, e.g. D2 | pinMode(2, INPUT_PULLUP) |
| Wire 2 | GND | The two wires are interchangeable |
With the internal pull-up resistor the pin reads LOW when the contact is closed and HIGH when it is open.
Usage tips
- The 220 V figure often quoted for these float switches is the contact breakdown voltage, not the working voltage: do not connect it directly to 230 V mains or to a pump. Use it to drive a relay coil or a controller input.
- Respect both limits, 0.5 A and 10 W: at 12 V, for example, the maximum is 0.5 A.
- When switching DC relay coils or solenoid valves, fit a flyback diode across the coil to protect the reed contact.
- Before mounting, check with a multimeter whether the contact is open or closed with the float down and, if you need the opposite logic, flip the float.
- Mount the stem vertically, leave room around the float so it moves freely and keep it clean of scale and deposits.
- To switch a pump on and off at two different levels, use two float switches mounted at different heights.
Package contents
- 1 float switch with nut and wires
Typical uses
- Water tanks and cisterns, aquariums and hydroponic systems
- Overflow or low-water alarms
- Automatic top-up with a pump or solenoid valve through a relay
- Arduino, ESP32 and Raspberry Pi projects
Warnings. This item is an electronic component (part, board, module or accessory) intended for people with technical skills in electronics, for development, prototyping, education, repair and integration into other equipment. It is not a ready-to-use finished product or a toy and is not suitable for children under 14. Wiring, power supply, installation and use are the buyer's responsibility, following the manufacturer's documentation and the applicable safety rules. Anyone who integrates it into equipment placed on the market becomes its manufacturer and must ensure its conformity (CE marking under directives 2014/30/EU on electromagnetic compatibility, 2014/35/EU on low voltage and, for radio functions, 2014/53/EU). Consumer rights under Italian Legislative Decree 206/2005, including the legal guarantee of conformity, are not affected.
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