26/35kV Busbar Heat Shrink Casing MPG35
Thick-wall cross-linked polyolefin casing for 26/35kV distribution busbar. Supplied expanded, recovered with heat onto copper or aluminium bar, it forms a continuous anti-tracking dielectric cover over the sections, joints and bends of a switchgear run. ID Φ30–Φ200mm covers the common bar sections at this class; red / yellow / green phase colours; service range -55℃~+125℃; built to ASTM D2671. Send the bar section (width × thickness) and length and we return the size code.
Specification
| Material | Polyolefin (cross-linked PE) |
|---|---|
| Operating temperature | -55℃~+125℃ |
| Voltage class | 26/35KV |
| Wall type | Thick wall |
| Colors | Red / yellow / green |
| Standards | ASTM D2671 |
| Size range | ID Φ30~Φ200mm |
What it is and how it recovers
MPG35 is extruded from cross-linked PE, expanded onto a mandrel and cooled, so it ships at the larger diameter. A hot-air pass or oven softens the polymer above its recovery temperature and the cross-linked network contracts the thick wall onto the bar. Wall thickness increases as the diameter closes, which is where the casing's dielectric and anti-tracking performance lives. The recovered cover conforms to rectangular sections, bends and bolted joints and holds its position after cooling; it does not relax back under operating temperature.
Selecting by busbar width × thickness
Busbar casing is sized to the section, and the section has two dimensions. The diagonal (hypotenuse of width × thickness, plus edge radii) sets the minimum supplied ID. The casing must pass the bar's largest cross-section. The width sets the recovered ID. The wall must close onto the flat with light interference so the cover grips. Order continuous lengths with margin: the casing shortens several percent during recovery, and a cover cut to bare length comes up short at the joints. The width × thickness range per size code is being verified for publication.
Edge, bend and joint handling
Thick-wall casing concentrates recovery pressure on whatever is sharpest underneath it. Deburr and radius bar edges before recovery; a burr under a closing thick wall is the common cause of a split cover. Over bends, support the casing so the outside radius does not thin excessively. At bolted joints, slide the casing over the bar before final bolt-up when the build sequence allows; on retrofits, choose an ID that clears the bolt heads and recover from the centre outward so air does not pocket at the joint.
System voltage limitation and creepage caveat
Two boundaries to respect. First, the casing's 26/35kV marking is a component class: a finished panel's insulation result also reflects phase spacing, support insulators and the enclosure design, so the cover does not transfer its marking to the system. Second, the casing insulates only the surfaces it wraps. It does not increase air clearances or the creepage path across support insulators. Keep the switchgear's designed creepage and clearances intact and treat the cover as the supplementary anti-tracking surface it is. MPG10 (8.7/15kV) is the thinner-wall class below this one; do not substitute it at 26/35kV, and do not assume MPG35 answers a higher class.
Installation and recovery conditions
- Prepare the bar. De-energize, bond, clean and dry; deburr and radius edges.
- Slide casing on before final bolt-up where possible; position with overlap past each joint face.
- Recover from centre outward with an even hot-air pass; allow the extra time a thick wall needs.
- Support long spans so the softened casing does not sag before it sets.
- Cool before handling; the cover then holds position for the life of the panel.
Frequently asked questions
How do I match MPG35 to my busbar width and thickness?
Read the bar section as width × thickness, not width alone. The supplied ID must pass the bar's diagonal (the section's hypotenuse sets the minimum expanded diameter), and the recovered ID must close onto it with light interference. As a rule, pick the size whose recovered ID range brackets the bar width while the supplied ID clears the diagonal plus edge radii. Send width, thickness and length per bar and we return the size code and cut lengths.
Does the casing cover busbar bends and bolted joints?
Yes, with edge discipline. The thick wall closes over bends and bolted connections and holds its shape after cooling, but it concentrates recovery force on whatever is sharpest beneath, so deburr and radius bar edges first, and over a bend back the casing so the outside radius is not stretched thin. Where the build sequence allows, slide the casing over the bar before final bolt-up; on assembled joints pick an ID that clears the bolt heads.
What does the 26/35kV rating on this casing actually mean?
It is the component class the thick wall and anti-tracking formulation are built for. A completed busbar system's insulation result also depends on phase spacing, support insulators, enclosure cleanliness and the enclosure's own design. The casing does not transfer its class marking to the whole panel. Verify the system's creepage and clearance per the applicable switchgear standard before relying on the cover alone.
What creepage and clearance caveats apply?
The casing insulates surfaces it covers; it does not increase the air distance between phases or to earth. Keep the switchgear's designed creepage path and clearances. The cover supplements them, it does not replace them. Where the enclosure is damp or polluted, the casing's anti-tracking surface helps, but the panel's insulation coordination remains the designer's responsibility.
How is the casing recovered, and what conditions does the work need?
A hot-air gun or oven recovers the wall onto the bar; work from the centre of each section outward so air does not pocket under the thick wall. The bar must be de-energized, clean and dry: dust under a recovering wall becomes a tracking path. Because the wall is thick, allow more heat time than thin-wall tubing, and support long spans so the softened casing does not sag before it sets. The casing shortens several percent longitudinally during recovery, so cut lengths with margin.
Which phase colors are available and how should we use them?
Red, yellow and green to match the IEC phase-colour convention. Hold one colour per phase across the whole installation so identification stays consistent from panel to panel, and buy multi-phase runs as a matched set from one batch. Masterbatch variation between batches can shift the shade slightly, which matters when two panels sit side by side.
Request a quote for MPG35 busbar casing
Send each bar's width × thickness and length, the phase colour split and total metres. We reply with size codes against the diagonal-and-width rule, cut lengths and lead time.
Certifications & Compliance
26/35KV Power Bus-Bar Heat Shrinkable Protective Casing MPG35 is built to the following standards. Certificates are supplied per batch on request.
For European grid tenders we can align documentation to IEC/EN equivalents and issue certificates per batch: name the standard your tender requires.
View our verified UL / SGS / RoHS certificates →
Size range & specification notes
Standard IDs run Φ30–Φ200mm, lengths cut to your bar dimensions; larger IDs and custom walls on request. Recovered wall thickness, per-size width × thickness coverage and recovery temperatures are published after verification: see the DATA_REQUIRED note above.