What the GS1TB4 Is and Where It Fits
The GS1TB4 is the body of a TeSys GS fuse switch disconnector — a 3-pole-plus-neutral unit that takes BS-type fuses and switches motor loads up to 800 A at 400 V in AC-23B duty. The 800 A figure is the rated operational current at 400 V in AC-23A and AC-23B service; at 690 V it derates to 630 A. That derating matters if your line runs at higher voltage — the switch's thermal capacity, not the fuse holder, is the limit. Breaking capacity is 6400 A at 400 V AC-23B; making capacity is 8000 A at the same condition. These numbers tell you the switch can close onto and interrupt fault currents up to those levels — relevant for coordination studies in a panel feeding a motor control centre.
Mounting, Connections, and Panel Fit
Mounts on a plate or DIN rail. The body dimensions are 19.7 in wide by 12.6 in high by 10.6 in deep — that 19.7-inch width means it spans most of a standard 24-inch panel depth, so plan the backplate layout accordingly. Power circuit connections accept bars or screw terminals up to 2 x 300 mm² flexible. Tightening torque for the bar connections is 389.4 lbf·in (44 N·m) — a torque wrench is expected, not optional. The operating handle mounts externally, either frontal or right-side.
Standards, Protection, and Durability
Designed to IEC 60947-3 (switch-disconnector standard) and IEC 60269-1/-2 (fuse standards). The body carries IP20 with the terminal cover fitted — finger-safe, but not washdown-rated. Fire resistance is 1760 °F (960 °C) for the body and 1562 °F (850 °C) for the fuse cover per IEC 60695-2-1. Mechanical durability is rated at 8000 cycles; electrical durability varies by duty — 500 cycles in AC-23A or AC-23B, 100 cycles in DC-23A or DC-23B. Ambient operating range is -4 to 158 °F (-20 to 70 °C). For a fuse switch that sits in a panel near a hot MCC bucket, the 70 °C ceiling is the one to check against your enclosure's internal temperature rise.