Busbar sleeve size chart — GSC, GMB and GHB series

A 100 x 10 mm bar through all three series

W+B is 110. Thin wall offers two candidates: GSC 100/50 covers 104 to 125, and GSC 120/60 opens at exactly 110. Take GSC 100/50, because 110 sits inside its band while in GSC 120/60 it sits on the boundary and a bar 1 mm under section falls out of the row.

Medium wall behaves the same way. GMB 100/38 covers 83 to 126 and GMB 120/45 covers 104 to 150, so both accept the bar, and GMB 100/38 is the tighter fit at 3.00 mm of wall.

Heavy wall is where the answer moves. GHB 100/38 stops at 102 mm W+B, so 110 falls outside it and the bar steps up to GHB 120/45, which covers 94 to 125 at 3.70 mm of wall. GMB 100/38 and GHB 100/38 carry the same D, the same d and the same 83 mm minimum; the heavy-wall maximum is 24 mm lower, and that alone drops the bar out of the 100 code.

So one piece of copper takes three part numbers depending on the panel it sits in: GSC 100/50 below 3.3 kV, GMB 100/38 to 24 kV, GHB 120/45 to 36 kV. That is 1.40, 3.00 and 3.70 mm of wall on the same bar, and the wall lands on both faces, so the finished section is about 2.8, 6.0 or 7.4 mm deeper across the breadth before the stated ±10% on T.

Wall thickness alone does not identify the grade. GMB 150/60 is 3.30 mm and GHB 25/8 is 3.20 mm, so the thickest medium-wall code carries more material than the thinnest heavy-wall one. The prefix carries the rating; the numbers after it do not.

The bands are not continuous, and the largest sizes are where that bites. Medium wall runs out at GMB 180/72's 226 mm and picks up again at GMB 205/85's 239 mm; heavy wall has the same hole and a wider one, from GHB 180/70's 196 mm to GHB 205/85's 239 mm. A bar of W+B 230 therefore has a thin-wall code and nothing above it.

Take a figure that lands in a hole to the manufacturer instead of forcing the nearest row. Every row has a floor as well as a ceiling, so stepping up a code can put the bar under the next row's W+B minimum and leave it bracketed by neither.

Reel length changes the shape of the order rather than the shape of the part. Two codes come on 100 m and two on 50 m, all four of them GSC; 23 codes come on 25 m, six on 20 m, two on 15 m and four on 1.5 m. Those four — GMB 205/85, GMB 250/100, GHB 205/85 and GHB 250/120 — are bought by the piece: a 6 m run is four pieces and three butts, and nothing in this chart says how a butt between two pieces is treated.

What this chart does not settle. It sizes the sleeve to the bar and stops there. It does not set the phase spacing the insulated bar then allows, it says nothing about the temperature rise of the copper underneath, and it does not reach bolted laps, tees or bar ends, which take a shroud, a bus sheet or an end cap rather than a length of sleeve. The voltage is carried by the series prefix, and no row in any of the three tables changes it.