Heat shrink tape vs electrical tape
The wrap that came undone on the hot bar was PVC tape doing what PVC tape does.
Electrical tape does not shrink
Somebody finds it, and it is almost never the person who wound it. A bolted connection in a panel, two or three summers on, with a black spiral hanging loose off one end and copper showing at the crest of every turn. Nobody put a flame near that tape. The bar did the heating, at the joint, hour after loaded hour.
PVC insulating tape does not shrink when it gets hot. Warmth softens the plasticiser, the adhesive loses its grip on the layer beneath, and the tension wound into the roll during application pulls the spiral open along its own seam. Anything that reads as shrinkage is the tape relaxing back towards the length it was stretched from.
That is also why the failure hides. The wrap looks correct for a season, then lets go from the inside, at the hottest point under it, which is the exact point somebody covered because it worried them. Sunlight does the same thing outdoors, more slowly.
So the answer to the search is no. The useful question is which wrap does hold. Three do, and every figure below comes off the manufacturer's own sheet for that product.
The three wraps that publish numbers
All three are manufactured by Gala Thermo Shrink Pvt. Ltd. of Palghar and Surat SEZ. None is a general-purpose roll, and none replaces the tape in an electrician's pouch.
Heat shrink tape, coded GMT-2L, is the only one of the three that recovers. It is supplied 50 mm wide, 1.0 mm thick to a tolerance of 0.10 mm, and 15 m to a roll. You wrap it by hand and then you heat it. Shrink temperature is 125 °C. The method is IEC 216. Continuous service runs from -40 °C to +115 °C on the same method, and dielectric strength is 22 kV/mm minimum. That method is ASTM D149. Recovery squeezes the adhesive into every surface irregularity underneath, and the imprint is permanent and solvent-resistant. It is halogen-free and anti-tracking.
Non-shrinkable insulation tape, coded GNT 1 and GNT 2, works the other way round. Nothing is heated. It is wound half-lapped at 50 percent overlap and the EPR cold flows, so successive layers bond into a single void-free body. Each layer contributes 0.75 mm, which means the build-up is counted in turns rather than ordered by size. Dielectric strength is 42 kV/mm, the highest of the three. The method is ASTM D149. GNT 1 is 25 mm wide on a 9.1 m roll, GNT 2 is 50 mm on 10 m, colour black, shelf life at least five years stored between +10 °C and +30 °C.
Mastic is cold-applied butyl and it is not an insulation build-up. It fills what the other two bridge over. Dielectric strength is 6 kV/mm minimum for black, 10 for red and 15 for the yellow stress-control grade. The method is ASTM D149. Service temperature is -20 °C to +90 °C for all three grades. That method is IEC 216.
One number needs care before anyone quotes it. The 36 kV attached to heat shrink tape is a switchgear application limit under ANSI C37.20.2. It is not a voltage rating for a wrap you built by hand, and it does not carry across to the other two products here.
Four rolls, side by side
The PVC column is empty wherever a figure would sit. This reference indexes one manufacturer's published data, ordinary insulating tape is not one of its products, and inventing a number to fill the column would defeat the table.
| Property | PVC insulating tape | Heat shrink tape GMT-2L | Non-shrinkable tape GNT | Mastic HBMT, HRMT, HSCM |
|---|---|---|---|---|
| Does it shrink | No. Heat softens it and the wrap relaxes | Yes. Recovery at 125 °C | No. It cold flows and amalgamates | No. It cold flows and fills |
| Dielectric strength | No figure held by this reference | 22 kV/mm minimum | 42 kV/mm | 6, 10 or 15 kV/mm by grade |
| Continuous service temperature | No figure held by this reference | -40 °C to +115 °C | Not published | -20 °C to +90 °C |
| How it is applied | Hand tension alone | Hand wrap, then a heat source | Hand wrap, half-lapped at 50 percent | Hand pressure onto a cleaned surface |
| Heat source needed | No | Yes | No | No |
| Supplied as | Not held here | 50 mm wide, 1.0 mm thick, 15 m roll | GNT 1 at 25 mm and 9.1 m, GNT 2 at 50 mm and 10 m, both 0.75 mm | Strips and rolls 20 to 35 mm wide, 1.7 to 2.5 mm thick, 100 to 25000 mm long |
| What the finished wrap is for | Colour coding, identification, bundling | Insulating and protecting medium-voltage bar connections, qualified to 36 kV | Building insulation thickness by hand on XLPE, PVC, PILC and rubber-sheathed jackets | Sealing, void filling and stress relief inside a joint or termination kit |
Published figures, and the method behind each one
| Property | Heat shrink tape GMT-2L | Non-shrinkable tape GNT | Mastic, black / red / yellow | Method |
|---|---|---|---|---|
| Tensile strength | 10.5 N/mm² minimum | 3 MPa | 0.1 / 0.5 / 0.1 MPa minimum | ASTM D638, and BS 903 for GNT |
| Ultimate elongation | 300% minimum | 900% | 300% minimum for all three | ASTM D638, and BS 903 for GNT |
| Dielectric strength | 22 kV/mm minimum | 42 kV/mm | 6 / 10 / 15 kV/mm minimum | ASTM D149 |
| Volume resistivity | 1 x 10^14 Ohm.cm minimum | 1 x 10^13 Ohm.m | 1 x 10^10 / 1 x 10^14 / 1 x 10^9 Ohm.cm | ASTM D257 |
| Dielectric constant | 5 maximum | Not published | 2 to 3 / 3 maximum / 10 minimum | ASTM D150 |
| Loss at 50 Hz | Not published | Loss angle 0.005 | Loss factor 0.035 for all three | ASTM D149 for GNT, not stated for mastic |
| Continuous temperature limit | -40 °C to +115 °C | Not published | -20 °C to +90 °C | IEC 216 |
| Shrink temperature | 125 °C | Does not shrink | Does not shrink | IEC 216 |
| Resistance to track and erosion | No tracking, erosion or flame failure up to 3.25 kV for 20 minutes | Not published | Not published | ASTM D2303 |
Not published means the manufacturer's published property table for that product carries no value for that row. It is not a zero. Two cautions on reading across: the volume figures are printed in different units, Ohm.cm for two products and Ohm.m for the third, so they are not comparable as they stand; and the mastic column gives black, red and yellow in that order.
Three gaps worth naming before you specify
The published property table for the non-shrinkable tape gives no continuous service temperature. Ask the manufacturer for it before putting that build-up beside a hot connection, because it is the one cell the comparison above cannot fill. The mastic sheet carries no ageing or heat-shock rows, which is consistent with a compound nothing ever heats, but the data is absent rather than passed. And no figure on this page is sourced for PVC insulating tape, because the manufacturer indexed here does not make it. What governs that roll is the rating printed on it and the tape standard it was qualified against, neither of which this reference holds.
When ordinary insulating tape is the right call
Most of the PVC tape on any site is doing work the three products above would be wrong for, and doing it well. None of these uses asks the tape to be the insulation.
- Phase and circuit colour coding. A narrow roll marks a core in seconds and comes off cleanly when the schedule changes. Nothing that recovers or amalgamates can be undone that way.
- Temporary identification through a shutdown, on cores the same crew will reconnect and unwrap.
- Bundling and dressing low-voltage wiring in a panel or a control cubicle. That is mechanical tidiness, not a dielectric duty.
- An outer identification or protection wrap over a finished, correctly specified build-up, where your own repair standard calls for one. It is the last layer applied, never the first.
Where this is the wrong part
None of the three is a jointing system. They are components that sit inside joint and termination kits, and a build-up assembled by hand from loose rolls is not a type-tested joint, because nobody has tested the geometry you made. None of them makes a bare conductor touch-safe either: 42 kV/mm is a property of 0.75 mm of EPR, not an approach distance. And none of them repairs a cable. A split jacket on a run nobody will take out of the ground is a wraparound sleeve, sized from the cable outside diameter, not a tape wound over the damage.
The questions behind the search
Does electrical tape shrink with heat?
Can I use electrical tape instead of heat shrink?
What is electrical heat shrink tape?
Which of these is the heat shrink tape for wires?
Do all three need a heat source?
The three products in full
- Heat shrink tapeGMT-2L on its own page: the full test table, the roll dimensions and what the shrunk adhesive seals against.
- Non-shrinkable HV insulation tapeGNT 1 and GNT 2, the half-lap method, and why a trapped void is the failure nobody sees.
- Mastic tapeThe HBMT, HRMT and HSCM selection chart, in strips and in rolls.
- What mastic tape isCold flow, void filling, and how much of it a boot actually wants.
- Black, red or yellow masticWhich grade a joint takes, and what the wrong grade costs you later.
- Reading a heat shrink datasheetWhat ASTM D149, ASTM D638, ASTM D2303 and IEC 216 are actually measuring.
Send the connection, not the tape
Bar section or cable outside diameter in millimetres, the voltage class, the surface temperature the wrap will sit at, and whether a flame is permitted at the working position. Those four pick one of the three products without a second email.