PET Fiberglass Cloth Tape

J-380 Electrical Filament Tape for Coil Banding and Lead Anchoring

J-380 is a filament reinforced electrical tape made with polyester film, glass filament reinforcement and pressure-sensitive acrylic adhesive. It provides low elongation and mechanical holding strength for coil banding, lead anchoring, end-turn taping and insulation-layer holding.

The series includes three grades. J-380 is the standard construction, J-380A is the economy grade for lighter mechanical loads, and J-380B offers the highest tensile strength. All three grades are primarily positioned for motors, coils and dry-type transformer assembly.

Although packaging filament tape may also contain glass fibers, it is not an appropriate substitute for J-380. This electrical filament tape is designed for applications where controlled thickness, dielectric performance, temperature rating and compatibility with insulation materials must be considered.

 

Product Attributes

Attribute	Specification
Product	Filament Reinforced Electrical Tape
Grades	J-380 / J-380A / J-380B
Backing	Polyester film with glass filament reinforcement
Adhesive	Pressure-sensitive acrylic adhesive
Total thickness	0.14 / 0.15 / 0.17 mm
Adhesion to steel	9–12 N/25 mm, depending on grade
Tensile strength	700–1200 N/25 mm, depending on grade
Elongation at break	5% typical
Dielectric breakdown voltage	5 kV typical
Temperature rating	Up to 155°C*
Standard roll length	50 m
Available formats	Standard and custom-width slit rolls
Main applications	Coil banding, lead anchoring, end-turn taping and dry-type transformer assembly

*The stated temperature rating applies to the individual tape grade under its specified conditions. It does not independently establish UL recognition or approval of a complete Class F electrical insulation system.

 

Technical Data

Property	J-380	J-380A	J-380B
Grade	Standard	Economy	Higher tensile
Adhesive	Acrylic	Acrylic	Acrylic
Total thickness	0.14 mm	0.15 mm	0.17 mm
Adhesion to steel	12 N/25 mm	9.5 N/25 mm	9 N/25 mm
Tensile strength	1000 N/25 mm	700 N/25 mm	1200 N/25 mm
Elongation at break	5%	5%	5%
Temperature rating	Up to 155°C	Up to 155°C	Up to 155°C
Dielectric breakdown voltage	5 kV typical	5 kV typical	5 kV typical
Standard roll length	50 m	50 m	50 m

The values shown are typical product data rather than guaranteed acceptance limits. Grade-specific tolerances, test directions and test methods should be confirmed in the current TDS before production approval.

Tensile strength and peel adhesion describe different aspects of tape performance. J-380B provides greater resistance to longitudinal loading, while its adhesion should be evaluated separately on the intended insulation surface. The actual contact surface may be PET film, insulation paper, copper strip, magnet-wire enamel or a varnished component rather than the steel panel used for the datasheet value.

The table lists 5 kV as a typical dielectric breakdown voltage for each grade. Where dielectric performance is an approval criterion, confirm the applicable test method and grade-specific data before ordering. A typical value should not be treated as a guaranteed minimum unless that limit is included in the agreed specification.

ASTM D1000 is commonly referenced for pressure-sensitive tapes used in electrical and electronic applications. If this standard is required, its use should be stated in the agreed TDS or product specification.

 

Selecting a J-380 Grade

J-380 Standard Grade

J-380 combines a typical tensile strength of 1000 N/25 mm with the highest adhesion-to-steel value in the series. It is the normal starting grade for general coil banding, lead anchoring and dry-type transformer assembly where both adhesion and mechanical holding strength are important.

J-380A Economy Grade

J-380A is the cost-effective option for lighter mechanical loads. Its reinforced construction provides mechanical holding for coil assembly and insulation-layer positioning where the full tensile performance of J-380 or J-380B is unnecessary.

Its 0.15 mm total thickness should not be interpreted as higher tensile strength. Total thickness includes the complete backing and adhesive construction; it is not a direct measure of the amount or arrangement of glass filament reinforcement.

J-380B Higher-Tensile Grade

J-380B provides a typical tensile strength of 1200 N/25 mm. It can be evaluated for higher wrap tension or more demanding mechanical holding positions where the standard grade does not provide enough tensile margin.

Its typical adhesion-to-steel value is 9 N/25 mm. Sample testing is recommended when it will be applied to insulation paper, PET film, enamelled wire or other non-steel surfaces.

The final grade choice should consider tape width, wrap pattern, application tension and coil geometry as well as the tensile figure.

 

Coil Banding and Winding Assembly

Glass filament reinforcement limits tape stretch during winding and handling. This helps maintain the position of conductor bundles and insulation materials while the coil is wound, transferred or prepared for the next production stage.

In selected coil-banding positions, J-380 can provide more mechanical holding strength than an unsupported polyester electrical tape. The required grade depends on the applied tension, tape width and number of wraps. A wider tape or a revised wrap pattern may sometimes provide a better result than simply moving to the highest-tensile grade.

J-380 is not intended to replace structural banding materials where the coil design requires a separate high-load reinforcement system. Its role should remain consistent with the mechanical and electrical requirements defined by the motor or transformer manufacturer.

 

Lead Anchoring and End-Turn Taping

Coil leads and end turns may move during winding, assembly, testing or transfer between workstations. J-380 can anchor these components and keep them in position until the remaining insulation and securing processes are complete.

The tape may contact magnet-wire enamel, strip copper, insulation paper, polyester film or a previously varnished surface. These materials can produce different adhesion results from the steel surface used for the datasheet value.

Where J-380 contacts magnet-wire enamel or passes through varnishing, resin treatment or baking, the complete process should be included in the sample test. Compatibility cannot be determined from the initial room-temperature bond alone.

Sharp conductor edges also require attention. The glass filament reinforcement improves tensile strength, but it does not prevent concentrated edges from cutting or puncturing the PET-based construction. Suitable insulation or edge protection should be used where necessary.

 

Dry-Type Transformer Coil Support

J-380 is mainly positioned for insulation holding and mechanical reinforcement in dry-type transformer production. Typical uses include:

· Holding insulation paper or polyester film during coil assembly

· Securing selected ground-insulation components in position

· Anchoring coil leads

· Banding selected winding sections

· Stabilizing insulation layers before varnishing, resin treatment or baking

The tape does not replace interlayer insulation, ground insulation, resin, varnish, spacers or the electrical clearances specified in the transformer design. It works as one supporting component within the complete insulation structure.

Our guide to power transformer insulation materials explains how reinforced tapes fit alongside DMD insulation paper, polyester film, aramid paper and other materials used in dry-type and oil-filled transformer systems.

For VPI and resin-treated dry-type transformers, J-380 should be tested with the actual varnish or resin. Adhesive behavior after impregnation and curing may differ from the initial adhesion measured before processing.

 

Electrical Filament Tape and Packaging Filament Tape Are Different Products

Both products may use glass fiber reinforcement, but they are made for different working conditions.

Packaging filament tape is generally selected for:

· Carton reinforcement

· Pallet stabilization

· Pipe or metal-profile bundling

· Appliance securing

· Export packaging

Its main performance requirements relate to package adhesion, impact resistance, transport loads and cost per roll.

J-380 is evaluated for electrical assembly. Low elongation, controlled thickness, dielectric breakdown voltage, temperature performance and compatibility with insulation materials are relevant to its approval.

A packaging-grade filament tape should not be used on motors or transformers merely because its tensile strength appears similar. Its backing continuity, adhesive chemistry and electrical data may be different.

 

J-380 Compared with Glass Cloth and Polyimide Tape

J-380, glass cloth tape and polyimide tape can all appear in motor or transformer production, but they do not perform the same role.

Selection point	J-380 Electrical Filament Tape	Glass Cloth Electrical Tape	Polyimide Tape
Backing	PET film with glass filaments	Woven glass cloth	Polyimide film
Common adhesive	Acrylic	Acrylic, rubber or silicone, depending on grade	Usually silicone or acrylic
Main advantage	High tensile strength and low elongation	Abrasion resistance, conformability and grade-dependent heat resistance	Thin high-temperature dielectric insulation
Surface	Film-based reinforced structure	Woven cloth surface	Smooth film
Typical role	Banding, anchoring and insulation holding	Coil wrapping, outer wrapping and mechanical protection	Thin electrical wrapping and high-temperature insulation
Varnish absorption	Limited by PET film	Some glass cloth constructions can absorb varnish	Normally non-absorbent

J-380 should not be treated as a direct replacement for glass cloth silicone tape. Glass cloth tape may be more suitable for outer wrapping, abrasion protection or positions requiring a different temperature and conformability profile. Polyimide tape is usually considered when thin-film dielectric performance and higher-temperature capability take priority over filament reinforcement.

Our electrical insulation tape material comparisons provide a broader view of these tape families when more than one construction is being evaluated.

 

Temperature Rating and Insulation-System Approval

The J-380 series has a stated temperature rating of up to 155°C. This value can be used as one material-selection parameter, but it does not represent approval of the complete transformer or motor insulation system.

The 155°C rating does not automatically mean that:

· J-380 is UL Recognized;

· The tape has independent Class F system approval;

· A motor or transformer becomes Class F by using the tape;

· The adhesive is compatible with every 155°C baking or curing process;

· Electrical and mechanical properties remain unchanged under every service condition.

Where UL recognition or inclusion in a particular electrical insulation system is required, the exact grade and supporting documentation should be confirmed before approval.

For operating conditions beyond the stated temperature range, glass cloth silicone electrical tape or polyimide tape may be more appropriate. The decision still depends on the location of the tape, mechanical load, required thickness and chemical exposure.

 

Oil-Filled Transformer Applications Use J-3801

J-380 is primarily intended for motor and dry-type transformer assembly. Transformer oil introduces a separate compatibility requirement that cannot be established from tensile strength, dielectric breakdown voltage or temperature rating alone.

For oil-filled transformer projects, J-3801 filament reinforced electrical insulation tape is the separate product to evaluate. J-3801 is not a suffix or variant of J-380, J-380A or J-380B.

Selection of J-3801 should be based on its own backing construction, adhesive system, temperature rating and available transformer-fluid compatibility data. The oil type, operating temperature, baking conditions and expected exposure period should be included in the sample request.

 

Production Testing Before Approval

A room-temperature hand test does not reproduce winding tension, baking, varnish exposure or long-term heat. A representative sample trial should follow the actual production process as closely as possible.

Useful checks include:

· Adhesion to the intended insulation surface

· Handling during winding and banding

· Stretch under normal application tension

· Edge lifting after baking

· Movement of leads or insulation layers

· Compatibility with varnish, resin or wire enamel

· Adhesive transfer after heat exposure

· Dielectric performance where required by the design

For projects still at the material-selection stage, our electrical insulation tape buying guide covers tape construction, operating temperature, process conditions and approval documents in more detail.

If lifting, shifting, edge damage or adhesive softening appears during production, review the tape together with surface preparation, winding tension, conductor geometry and the bake profile. Our electrical insulation tape failure analysis provides further checks for separating material-related failures from process conditions.

 

Custom Slitting and Roll Supply

J-380 can be supplied in standard or custom slit widths. Tape width affects holding area, load distribution, wrapping speed and material usage, so it should be selected together with the grade.

Available supply options include:

· Custom-width slit rolls

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