What the 100 A rating means for panel fit
The GS2JU3 is a 3-pole switch-disconnector-fuse rated 100 A conventional free-air thermal current (Ith) at 40 °C, and the same 100 A as its rated operational current (Ie). That means it handles continuous 100 A loads without derating at 40 °C ambient — a common panel temperature. For higher ambients, the Ith rating is the limiting factor; the 100 A figure is the ceiling at 40 °C, not a blanket rating. The 22 kA short-circuit withstand rating (SCCR) at the stated voltage is the key coordination number for the panel builder: it tells the upstream protection device what fault level this switch can survive without welding or rupturing. That 22 kA is the interrupting rating of the fuse holder itself, assuming the correct J-class fuse is installed.
Standards and compliance documentation
Certified to UL98 and CSA C22.2 No 4 — these are the governing standards for enclosed and dead-front switches in North America. UL98 covers the switch-disconnector function; CSA C22.2 No 4 covers the same for Canadian installations. The body material is rated for 960 °C fire resistance per the glow-wire test, which satisfies the thermal stress requirements of both standards. The IP20 rating (with terminal cover fitted) means the enclosure protects against solid objects larger than 12.5 mm — fingers, tools — but not against moisture. This is standard for panel-mounted disconnect switches where the panel door provides the environmental seal. The operating handle is external frontal, so the switch can be operated with the door closed.