Heat shrink tubing with an inner layer of hot-melt adhesive that creates a waterproof seal during shrinking. Also called dual wall.
Aging Test
Accelerated test where material is held at elevated temperature (e.g., 158°C for 7 days) to simulate long-term thermal degradation.
Anti-Tracking
Material property that resists formation of conductive carbonized paths on the surface under electrical stress and contamination. Important for outdoor terminations.
ASTM D638
Standard test method for tensile properties of plastics. Used to measure tensile strength and elongation of heat shrink tubing.
ASTM D2671
Standard test method for heat-shrinkable tubing, including longitudinal change and heat shock.
AWG
American Wire Gauge. Standard for wire diameter. Higher AWG numbers = smaller wire. E.g., AWG 10 ≈ 5.8 mm².
B
Bias Wall (Wall Bias)
Maximum variation in wall thickness around the circumference of the tubing after recovery. Expressed as a percentage. UL 224 limit: ≤30%.
Breathing Effect
Thermal expansion and contraction of XLPE cable insulation during load cycling. Silicone rubber cold shrink accommodates this without gap formation.
Busbar
Conductive bar (copper or aluminum) used to distribute electrical power in switchgear, panels and transformers.
Bushing
Insulated terminal through which a conductor passes from one environment to another, e.g., from transformer tank to air.
C
Cable Accessories
Collective term for terminations, joints, connectors and related hardware used to connect or terminate power cables.
Cable Joint
Permanent connection between two cable ends. Restores insulation, screening and outer protection. Also called a splice.
Cable Termination
Assembly that connects a cable end to equipment (switchgear, transformer, overhead line) while maintaining insulation integrity.
Cold Shrink
Pre-stretched silicone or EPDM tubing that contracts when the removable support core is pulled out. No heat required.
Continuous Operating Temperature
Maximum temperature at which the material can function indefinitely without significant degradation. Typically 105°C or 125°C for polyolefin.
Creepage Distance
Shortest distance along the insulation surface between two conductive parts. Critical for outdoor terminations in polluted environments.
Cross-Linking
Chemical or radiation process creating covalent bonds between polymer chains. Gives heat shrink tubing its shape memory — the ability to shrink back to original diameter when heated.
Copper Stability
Test to verify that the tubing does not corrode copper conductors during aging. Requirement: no visible corrosion after 158°C, 7 days.
D
Dielectric Strength
Maximum electric field a material can withstand without breakdown, measured in kV/mm. Typical polyolefin: 20-25 kV/mm.
Direct Burial
Installation method where cable and accessories are buried directly in soil without conduit. Requires moisture sealing and mechanical protection.
DOT 3
Specification for motor vehicle brake fluid. Used in fluid immersion testing of automotive heat shrink tubing.
Dual Wall
See Adhesive-Lined. Tubing with two layers: outer polyolefin for insulation, inner hot-melt adhesive for sealing.
Duct Bank
Underground arrangement of pipes (ducts) through which cables are pulled. Joint protection must resist water ingress in flooded ducts.
E
Elongation at Break
Percentage increase in length at the point of tensile failure. Higher values indicate greater flexibility. Typical polyolefin: ≥300%.
EPDM
Ethylene Propylene Diene Monomer. Synthetic rubber used in cold shrink applications for weather resistance and electrical properties.
Expanded ID
Internal diameter of unshrunk heat shrink tubing as supplied. Must be large enough to slide over connectors and joints.
F
Flame-Retardant
Material that resists ignition and slows flame spread. Typically meets UL 94 V-0 or IEC 60332 requirements.
Finger Sleeve (Breakout Boot)
Multi-finger heat shrink sleeve that separates and insulates individual cores at a cable breakout point.
G
GB/T 12706.4
Chinese national standard for power cables with extruded insulation and their accessories, 6 kV to 30 kV.
H
Halogen-Free
Contains no fluorine, chlorine, bromine or iodine. Produces less toxic smoke when burned. Required for rail, marine and enclosed spaces.
Heat Shock Test
Test where material is exposed to high temperature (e.g., 250°C for 4 hours) then checked for cracking or degradation.
Heat Shrink Ratio
Relationship between expanded and recovered ID. E.g., 3:1 means tubing shrinks to one-third of its original ID.
Heavy Wall
Heat shrink tubing with thick walls (>2 mm recovered) for mechanical protection and direct burial applications.
Hot-Melt Adhesive
Thermoplastic adhesive layer in dual-wall tubing that melts at 85-110°C and flows to fill voids, creating a waterproof seal upon cooling.
I
IATF 16949
International automotive quality management standard. Required by OEM and Tier 1 automotive suppliers.
IEC 60502-2
International standard for power cables with extruded insulation and their accessories for rated voltages from 6 kV to 30 kV.
IEC 60332
Standard for test on electric cables under fire conditions — flame propagation.
IEC 60684
International standard for flexible insulating sleeving.
IEC 60754
Standard for gases evolved during combustion of materials from cables — halogen acid content determination.
Impulse Withstand
Ability of insulation to withstand lightning or switching impulse voltage surges without breakdown. Tested at 105-250 kV depending on voltage class.
Incoterms
International Commercial Terms defining buyer and seller responsibilities for delivery, risk and cost. Common: EXW, FOB, CIF, DDP.
J
Joint (Cable Joint)
Permanent connection between two cable ends restoring all layers: conductor, insulation, screen and outer sheath.
L
Load Cycle Test
Type test where the cable assembly is heated (conductor to 90-95°C) and cooled through multiple 8-hour cycles to simulate operational thermal stress.
Longitudinal Shrinkage
Amount a tube shortens in length during shrink, typically ≤±8% for quality tubing.
LOI (Limited Oxygen Index)
Minimum oxygen concentration needed to support combustion. Higher = more flame retardant. MPG series: LOI >30.
LSZH
Low Smoke Zero Halogen. See Halogen-Free.
LV 112
German automotive cable standard. Referenced for EV high-voltage cable identification (orange color).
M
Mastic
Butyl-based sealant used in cable joints. Flows under compression to fill surface irregularities and create a moisture barrier.
Medium Wall
Wall thickness between thin wall and heavy wall, typically 1-2 mm recovered.
MIL-DTL-23053
U.S. military detail specification for heat-shrinkable tubing. Used as reference for defense applications.
MOQ
Minimum Order Quantity.
MV
Medium Voltage. Typically 1 kV to 36 kV.
N
Nitrile Rubber
Synthetic rubber with excellent oil resistance. Sometimes used as adhesive layer in automotive dual-wall tubing.
O
Oxygen Index
See LOI (Limited Oxygen Index).
P
Partial Discharge (PD)
Small electrical sparks occurring within insulation voids or at interfaces. Measured in pC (picocoulombs). Lower is better. IEC 60502-2 requirement: ≤10 pC for MV accessories.
Pilc
Paper-Insulated Lead Covered cable. Older cable type requiring special transition accessories for connection to XLPE cables.
Polyolefin (PO)
Family of polymers (polyethylene, polypropylene) commonly used for heat shrink tubing due to good electrical properties and shrink behavior.
PTFE
Polytetrafluoroethylene (Teflon). High-temperature fluoropolymer used for heat shrink up to 260°C.
Power Frequency Withstand
Test where the insulation is subjected to AC voltage (e.g., 45 kV for 1 minute) without flashover or breakdown.
R
Recovered ID
Internal diameter after full shrinkage. Must be smaller than the object being covered for a tight fit.
Recovery Temperature
Temperature needed to initiate shrinking. Polyolefin: 90-110°C. PTFE: 327°C.
RoHS
Restriction of Hazardous Substances. EU Directive 2011/65/EU limiting lead, mercury, cadmium, hexavalent chromium, PBB and PBDE.
S
Screen (Cable Screen)
Metallic layer (copper tape or wires) around the cable insulation providing earth fault current path and electric field confinement.
Shrink Temperature
See Recovery Temperature.
Silicone Rubber
High-temperature elastomer used in cold shrink products. Flexible from -50 to 200°C.
Stress Control
Method of managing electric field concentration at the cable screen cut. May use geometric (stress cone) or resistive (non-linear material) approach.
Stress Cone
Truncated conical geometry at the cable termination that distributes electric stress gradually from the screened to unscreened region.
T
Tensile Strength
Maximum stress a material can withstand before breaking, measured in MPa. Typical polyolefin: ≥10 MPa.
Thermal Shock
Rapid exposure to extreme temperature to test material stability. E.g., 250°C for 4 hours or -55°C for 4 hours.
Type Test
Test performed on a representative sample to verify design compliance with a standard. Required for MV cable accessories per IEC 60502-2.
U
UL 224
Underwriters Laboratories standard for heat-shrinkable tubing covering flammability, dielectric strength and physical properties.
UL 94 V-0
Flammability rating: material stops burning within 10 seconds after flame removal with no flaming drips.
V
Volume Resistivity
Electrical resistance per unit volume, measured in Ω·cm. Higher = better insulation. Typical polyolefin: ≥10¹⁴ Ω·cm.
W
Wall Thickness
Thickness of tubing wall after full recovery. Thicker walls provide better mechanical protection and insulation.
Water Absorption
Percentage of water a material absorbs over time. Lower is better for sealing. Typical polyolefin: <0.5%.
Withstand Voltage
Voltage level that insulation must tolerate for a specified duration without breakdown.
X
XLPE
Cross-Linked Polyethylene. Most common MV cable insulation. Our cable accessories are specifically designed for XLPE cables.
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