Rule 40A Float Switch – Rugged, Reliable Bilge Pump Control

The Rule 40A Float Switch, part of the trusted Rule-A-Matic Plus Series, is a compact, heavy-duty solution designed to provide automatic bilge pump activation. Built for both commercial and recreational vessels, it delivers consistent performance even in the toughest marine conditions. The switch activates your pump only when necessary—when water levels rise—making it both efficient and dependable.

The Built Rule 40A Float Switch is built to Last in Harsh Marine Conditions

The Rule 40A Float Switch is engineered with an impact-resistant, fully integrated cover that protects the internal float from physical damage and debris. A debris-resistant strainer prevents blockages that could interfere with operation, while moisture-tight seals ensure long-term performance in wet, corrosive marine environments. It supports 12, 24, or 32-volt systems and works with pumps drawing up to 20 amps, offering wide compatibility with various non-automatic bilge pumps.

Safe, Mercury-Free Design

This float switch is also designed with safety and sustainability in mind. The mercury-free switch mechanism meets modern environmental and safety standards, providing reliable pump control without hazardous materials. An external test lever lets you manually lift the float to check system operation—giving you peace of mind before every voyage.

Compact, Simple, and Durable

Measuring 2-7/8″ H x 2-1/2″ W x 5-1/4″ L, the compact form makes installation easy, even in tight bilge compartments. The snap-on base allows for quick installation and maintenance, while marine-grade 14-gauge, abrasion-resistant wiring ensures strong, lasting electrical connections in any environment.

Whether you’re upgrading your existing bilge system or replacing a worn or outdated switch, this product delivers dependable automatic operation, rugged marine-grade durability, and straightforward installation. Designed to perform in harsh marine environments, it’s a trusted, long-lasting solution that makes it a top choice for serious boaters, anglers, and marine professionals who demand reliability and performance on the water.