Reference
Busbar sleeving questions, answered short
Ten answers, each with a figure in it — opening on the four codes a 40 x 6 mm bar can take and closing on the four things nobody publishes.
Sizing a sleeve to a bar
My bar is 40 x 6 mm. Which code do I order?
Add the two section dimensions and work from 46. At 415 V or 3.3 kV that figure sits in GSC 40/20, whose rectangular band runs 44 to 52 mm at a recovered wall of 0.96 mm. At 11 or 22 kV the medium-wall part is GMB 40/16, banded 33 to 50 mm at 2.10 mm, with GMB 50/20 accepting the same bar more loosely across 38 to 63 mm. At 33 kV it becomes GHB 50/20, 45 to 54 mm at 3.50 mm. One piece of copper, four defensible codes, and the only variable between them is the panel's system voltage.
Why does the heavy-wall answer jump to a 50-series code?
GHB 40/16 closes at 45 mm and the bar reads 46. A millimetre outside a published band is outside it, and the consequence is physical rather than administrative: a sleeve that finishes recovering before it meets the copper leaves the air gap the grade was bought to remove. The bands are not scaled copies of one another either. GMB 40/16 accepts 33 to 50 mm where GHB 40/16 accepts only 35 to 45 mm, because the heavier material has less recovery left to give. Read the band on the row you are actually buying, never the nominal number in the code.
Does one grade cover more than one voltage?
Yes — each grade is a band rather than a point. GMB is rated to 24 kV, so one medium-wall part serves 3.3, 6.6, 11 and 22 kV panels unchanged. What does not travel is the boundary between grades. Move from 22 kV to 33 kV and the specification steps to GHB, and as the 46 mm bar shows, the size code frequently moves with it. The digits in a code carry no rating at all; only the GSC, GMB and GHB prefix does. GMB 50/20 and GHB 50/20 share a nominal size and are different parts — 2.10 mm of recovered wall against 3.50 mm.
Can I get six metres of that in one continuous length?
At this section, yes. GSC 40/20 is listed on 50 m reels, and GMB 40/16 and GHB 50/20 on 25 m, so a six-metre run is a cut length and not a jointing exercise. Short supply lengths appear only at the very top of the chart, where the 205 and 250 codes are listed at 1.5 m. Read the reel column before assuming any long run arrives whole.
The conductor is round tube, not flat bar.
Then the width-plus-breadth sum does not apply and the measured diameter is read straight off the Round Ø columns instead. The same three codes span quite different figures there: GSC 40/20 takes 28 to 33 mm diameter, GMB 40/16 takes 21 to 32 mm, and GHB 50/20 takes 29 to 40 mm. A flat bar summing to 46 and a 46 mm round tube are two separate selections and never share a row.
Fitting, adjacent parts and scope
Can a sleeve be fitted without dismantling the bar?
No. A tube is threaded over a free bar end, so every bolted lap, tee, dropper and support in its path has to come apart before it arrives. Where a strip-down is unacceptable, the parts that fit around assembled geometry are the moulded BUSBOOT shroud, supplied complete with its fasteners, the wrapped bus sheet, and GBBS barrier board standing in the air gap rather than on the conductor. Be clear about what that buys, though: avoiding a strip-down is not the same as avoiding an outage, and nothing in this range is a live-working part.
Shroud or cap? Both words turn up in the same enquiry.
A shroud covers a connection — two or more bars meeting at a tee, an elbow or a bolted lap — and is catalogued by connection type rather than by bar width. A cap covers the flat cut end of a single bar and nothing beyond it. Both are moulded, both carry the ANSI C37.20.2 switchgear rating to 36 kV, and both lift off in minutes for a re-torque or a thermographic check. If the drawing shows bolts at that position you want a shroud; if it shows the copper simply stopping, you want BUSCAP.
Does sleeving change what the bar can carry?
Nothing in the published range answers that, so neither does this site. No current rating, temperature rise or derating factor for a covered bar appears on any of the manufacturer's busbar sheets. The one thermal pair that does exist belongs to the covering rather than the conductor: −40 °C to +115 °C continuous for the cross-linked polyolefin, recovering at 125 °C. Ampacity is a busbar design calculation, and it wants settling before a covering is specified rather than after.
Does a sleeve seal the bar?
Not in the ingress sense, and no IP figure is published for any part specified on this site. What the manufacturer does publish for the sleeve is protection against chemical corrosion by strong acid, alkali and salt — a claim about the surface of the copper, not about keeping an enclosure dry. The adhesive-backed member of the family is the bus sheet, where the adhesive is quoted as extra thickness on the sheet and not as a sealing specification.
Is there a PDF I can attach to a bill of materials?
Yes. The heat-shrink busbar tube datasheet carries the GSC, GMB and GHB tables and the rectangular clearance set, and that document is the one to cite in a submittal. Every table on this site is transcribed from it and from the manufacturer's product pages; where a transcription and the PDF ever disagree, the PDF is what goes on the drawing.
Price, lead time, minimum quantity and stock
Four questions this site does not answer. None of the four is published on the manufacturer's sheets either, so any figure printed here would have been invented. They come from Gala Thermo Shrink Pvt. Ltd. directly, through the manufacturer's contact page or through the enquiry route on this site. Send the bar section, the system voltage and the run length alongside the commercial question, and the answer comes back with a part number already attached to it.
Where each answer continues
An FAQ compresses. These pages carry the tables the answers above were cut from.
- Busbar sleeve size chartThe 44 to 52 and 45 to 54 bands quoted above, and the other 34 codes, with D, d, wall and reel length.
- The sleeve itselfWhat each of the three grades is rated to, and how a code such as GHB 50/20 is read.
- Installing a busbar sleeveThe eight-step bench sequence behind the threading answer, and the four recovery defects to inspect for.
- Busbar connectionsWhich geometry takes a shroud, which takes a cut sheet, and which takes a cap.
- Busbar insulation standardsANSI C37.20.2 and IEC 216, decoded in one place.
- Busbar air clearanceThe millimetres a covered bar buys back, and the reason any of this is worth doing.
Send a section, a voltage and a run length
Three fields turn any question on this page into a part number: width x breadth in millimetres, or the diameter for round conductor; the system voltage the panel is designed to; and the metres to be covered. Stated limit: this page answers questions about specifying and fitting a covering. It establishes nothing about the bar underneath — not its ampacity, not its temperature rise, and not the withstand the finished assembly will eventually be type-tested to.