You've hit on a common point of confusion! Let's break it down: "Suitable for circuit breakers or fuses" means the device can work with either type of overcurrent protection. It's versatile. "Max fuse" (or similar wording) refers to the maximum ampere rating of a fuse that the device is designed to handle safely. This is a crucial safety specification.

My opinion, based on typical electrical component design

The device can be used with a circuit breaker or a fuse,

BUT the fuse, if you choose to use one, must not exceed the maximum ampere rating specified.In other words


You are NOT required to use a fuse. You can use a circuit breaker instead, as long as the circuit breaker is appropriately sized for the circuit and the device it protects.2. If you DO choose to use a fuse, its ampere rating must be equal to or less than the "max fuse" rating stated. Using a fuse that's rated higher than the maximum specified is a serious fire hazard.

Why this distinction? Protection

The manufacturer has tested the device to ensure it can safely handle the heat and energy released during a short circuit or overload when protected by an overcurrent device (fuse or circuit breaker) up to a certain level. The "max fuse" rating is that level.

Coordination

The "max fuse" rating might be chosen to ensure that the fuse blows before the device itself is damaged in an overcurrent situation.

How to proceed safely


Consult the device's documentation thoroughly. Read the specifications, installation instructions, and any warnings.2. Determine the correct overcurrent protection (fuse or circuit breaker) based on the connected load and wiring. This is determined by electrical code and the device's ampacity (current-carrying capacity).3. If using a fuse, make absolutely sure its ampere rating is no higher than the "max fuse" rating specified for the device. It can be lower, if appropriate for the load, but NEVER higher.4. If using a circuit breaker, ensure it has an appropriate interrupting capacity and ampere rating for the circuit.

In summary, the wording does NOT mean fuses MUST be used. It means that if fuses are used, the ampere rating cannot exceed the specified maximum. When in doubt, consult a qualified electrician. Electrical work can be dangerous, and proper installation and protection are essential for safety. Flag for review