Reusable boots
Reusable rubber insulating boots
One catalogued size, GRRB-1: 44.0mm minimum at the bushing entry, 20.0mm at the cable entry, over bushings of 46 to 70mm.
Three minimums, and no recovered figure at all
Fit is settled here by minimums rather than by a pair. GRRB-1 is published with an ID bushing entry of 44.0mm minimum and an ID cable entry of 20.0mm minimum, against a stated bushing diameter of 46 to 70mm. The rubber stretches across that band, which is what range-taking means on a moulded elastomer.
This is the one part indexed on this site that carries no a and b column. Every heat-shrink boot here publishes an as-supplied minimum beside a recovered maximum, because recovery runs one way. The reusable boot publishes minimums only, and the manufacturer describes it as designed for disconnection and reusability.
So the decision is not between two shapes. It is between a part that goes on once and a part that comes off again, and what the termination's future holds is what settles it. A GRB or GSB boot recovers with heat at 125°C and stays where it lands. A GRRB is pulled off and refitted as often as the work requires.
That is the maintenance argument, and it is the one that usually decides this part. Direct voltage testing is listed as a feature of the reusable boot, and its sheet publishes a DC withstand of 48 kV held for 30 minutes. The connection can be energised immediately after installation, in the manufacturer's own wording, so refitting does not add a wait to the outage.
GRRB-1 reusable insulating boot
A modified silicone/rubber shroud for all types of termination on PILC and XLPE cable. It carries the flexibility and the dielectric strength needed between phase and phase and between phase and ground, and it seals the cable, the cable lug and the bushing together. Manufactured by Gala Thermo Shrink Pvt. Ltd.
- Installs and removes as often as required, and is designed for disconnection and reusability
- Facilitates direct voltage testing
- The connection can be energised immediately after installation
- Range-taking capability across the published 46 to 70mm bushing band
- Complete sealing of the cable, the cable lug and the bushing, against rodent ingress and high humidity
- RoHS and REACH compliance marked on the datasheet
| Catalogued sizes | One, GRRB-1 |
|---|---|
| ID bushing entry | 44.0 mm (min.) |
| ID cable entry | 20.0 mm (min.) |
| L1 | 175.0 mm (min.) |
| L2 | 170.0 mm (min.) |
| Bushing diameter | 46 – 70 mm |
| AC high voltage (datasheet) | 35 kV for 5 minutes |
| Maximum system voltage (manufacturer's product page) | 36 kV for 1 minute AC |
| DC high voltage | 48 kV for 30 minutes |
| Basic impulse level | 95.0 kV |
| Material | Modified silicone/rubber shroud |
| Cable types | PILC and XLPE terminations, all types of termination |
| Voltages named as economically viable | 11 kV and 22 kV |
GRRB selection chart
| Product code | ID bushing entry (min.) | ID cable entry (min.) | L1 (min.) | L2 (min.) |
|---|---|---|---|---|
| GRRB-1 | 44.0 mm | 20.0 mm | 175.0 mm | 170.0 mm |
One catalogued row, and every figure in it is a minimum. There is no recovered column on this part. Source: the manufacturer's Bushing Boot and Reusable Insulating Boot datasheet.
Recovered once, or off and on again
Both parts insulate a bushing inside a termination box, and the trade calls both of them boots. The figures come from the two published documents this page works from.
| GRB and GSB, heat shrink | GRRB-1, reusable | |
|---|---|---|
| Material | Cross-linked non-tracking polyolefin | Modified silicone/rubber shroud |
| Internal lining | Water-resistant red mastic | None listed on the reusable sheet |
| Going on | Recovered with heat, shrink temperature 125°C | Stretched over the bushing; no shrink temperature is published |
| Coming off | Recovery runs one way | Designed for disconnection and reuse |
| How a size reads | a as supplied, b after unrestricted recovery | Minimums only, no recovered figure |
| Catalogued sizes | GRB-1, GRB-2, GRB-2A, GRB-3, GSB-1, GSB-2, GSB-2A, GSB-3 | GRRB-1 |
| Electrical figure published | Dielectric strength 15 kV/mm minimum | AC 35 kV for 5 min, DC 48 kV for 30 min, BIL 95.0 kV |
| Tracking and erosion | No failure at 3.25 kV held for 20 minutes | Not published on the reusable sheet |
| Continuous temperature | −40°C to +110°C | Not published on the reusable sheet |
| Where the figures come from | The manufacturer's right angle and straight boot page | The Bushing Boot and Reusable Insulating Boot datasheet |
What this part is not
Each line below is a statement about what the published record contains, not a caveat.
- Not a bushing boot. GSBB-1 and GSBB-2 share the datasheet and carry their own selection chart. That chart is not reproduced here, and the two products are not interchangeable by code.
- Not a heat-shrink part. No shrink temperature appears on its sheet and no recovered diameter is published for it, so nothing on the boot changes state during fitting.
- Not backed by a test method. The reusable boot's sheet lists four electrical figures and one selection chart, with no ASTM, IEC or ESI method printed beside any value.
- Not a size range. One code covers the whole published 46 to 70mm bushing band, so a bushing outside it has no catalogued reusable boot at all.
- Not the switchgear bushing case. Bushing boots, the GTPE-500 terminal protector and the GSTB and GRTB ranges are covered on 66kvcabletermination.com, a sister reference published by the same operator as this site. No table from them appears on this page.
Two AC figures for the same boot
The manufacturer's product page gives a maximum system voltage of 36 kV for one minute AC. The datasheet for the same part gives an AC high voltage of 35 kV for five minutes. Both appear in the specification above with the document each came from, because the sources this site works from do not resolve the difference. The five-minute figure is the one printed beside the selection chart.
Not published: material grade, temperature limits, hardness
The reusable boot's sheet gives a selection chart, four electrical figures and a bushing diameter band. It gives no continuous operating temperature, no hardness, no tracking or erosion figure and no material grade beyond "modified silicone/rubber". A second bushing entry or a larger cable entry is a question for the manufacturer, not a gap this site can fill.
Two diameters answer it
The bushing diameter and the cable diameter decide whether GRRB-1 fits at all. An enquiry carrying both, with the cable type and the system voltage, is answered in one reply rather than four.