It carries a continuous current rating of 25 A and an interrupting capacity of 440 kA at 240 V, dropping to 330 kA at 415 V and 220 kA at 500 V — so on a 480 V bus you've got headroom for high-fault locations like a main secondary breaker. The 4-pole construction handles three-phase-plus-neutral or dual-feed configurations.
The front face carries an IP40 rating, meaning tools and fingers stay out, but it's not sealed against washdown — keep it inside the enclosure, not on the wet side of the panel.
What the ETU550 trip unit gives you
The ETU550 is an electronic trip unit with communication capability — it can talk to a higher-level system for power monitoring and alarm annunciation, not just trip status. That's useful for a facility engineer who wants to see load profiles or fault events without walking the panel line. Power loss is negligible at 0.5 W maximum.