3M 7000031629 Scotch Varnished Cambric Tape 2520, 3/4 in x 60 ft, Yellow, 1 roll/carton, 20 rolls/Case

Rated to 105 C (220 F) continuous operating temperature, which puts it in line with Class A insulation systems. That covers most motor leads, lighting fixture wiring, and appliance work. If the surface runs hotter than that, step up to a glass cloth or silicone-based electrical tape instead.

They do different jobs. Scotch 2520 has a woven cotton cloth carrier, so it does not stretch and conform the way a vinyl tape does around irregular splices, and it is not a moisture seal. Where it wins is heat and mechanical toughness: 105 C rating, 876 N/100mm tensile strength, and a hard-wearing surface for wrapping coils, leads, and bundles. Many electricians use cambric as the insulating body and finish with vinyl as the outer jacket.

The 2520 is listed against ASTM D-1000, ASTM D-295, and ASTM D-374, carries a UL 94 V-2 flammability classification, and is RoHS 2011/65/EU compliant. That set is what most electrical construction submittals ask for on an insulating cloth tape.

8 mil thick (0.203 mm) with a dielectric strength of 800 V/mil, so a single wrap carries a substantial breakdown margin and half-lapped layers build quickly. That thickness also means it adds real bulk in a tight slot or conduit body, so count your layers when space is limited.

The 2520 roll is yellow, and crews do use colored cloth and vinyl tapes for phase identification, but this is an insulating tape first. If the only thing you need is phase marking, a thin vinyl color-coding tape is the cheaper and lower-bulk choice; the 2520 at 8 mil is meant to do insulating work as well.

It is a straight-cut woven cotton cloth tape with 876 N/100mm tensile strength, so it hand-tears cleanly across the width along the weave rather than stretching like vinyl. That same tensile strength is why it holds up as a mechanical wrap over leads and coil ends.

Country of origin on the 2520 cambric tape is the United States, which matters on public and institutional jobs carrying domestic-sourcing language in the specification.