A wire compound is the polymer material extruded around a conductor or cable core. A PVC cable compound is a PVC-based wire compound formulated for a defined job, such as electrical insulation or an outer sheath. Buyers should specify that job first, then name the cable standard, temperature class, hardness target and test requirements.
The grade name alone is not enough. Values for tensile strength, elongation, volume resistivity, dielectric strength and aging performance must come from the approved technical data sheet (TDS), sample report or batch certificate of analysis (COA). They should not be copied from a generic web table.
What is PVC wire compound?
PVC wire compound is a ready-to-extrude mixture based on polyvinyl chloride resin. A formulation may also contain plasticizers, stabilizers, fillers, lubricants, pigments and other additives. The formulation controls how the material processes and how the finished insulation or sheath behaves.
Raw PVC resin and cable-grade PVC compound are not interchangeable purchasing terms. Resin is one input. Compound is the formulated material supplied to the cable extrusion line.
In a cable specification, “PVC compound” still needs a functional description:
- Insulation compound applied directly over the conductor
- Core insulation compound used inside a multicore cable
- Inner sheath or bedding compound
- Outer sheath compound
- Flexible cord compound
- Flame-retardant, oil-resistant, weather-resistant or other project-specific grade, where a named test supports the claim
The relevant finished-cable standard remains the controlling document. For example, IEC 60227-1:2024 covers PVC-insulated rigid and flexible cables up to and including 450/750 V. IEC 60502-1:2021 covers extruded-insulation power cables for rated AC voltages of 1 kV and 3 kV. A material described for one scope should not be assumed suitable for the other.
PVC insulation compound vs PVC sheath compound
Insulation and sheath compounds can both be PVC, but they have different priorities.
| Selection point | PVC insulation compound | PVC sheath compound |
|---|---|---|
| Position | Directly over the conductor or insulated core | Over the assembled cable structure |
| Main function | Electrical separation | Mechanical and environmental protection |
| Electrical checks | Volume resistivity, insulation resistance or dielectric properties as required by the governing specification | Normally secondary unless the cable specification requires an electrical property |
| Mechanical checks | Tensile strength, elongation, stripping behavior and resistance to deformation | Tensile strength, elongation, abrasion or impact performance when specified |
| Thermal checks | Temperature class, air-oven aging, hot pressure, heat shock and loss of mass where applicable | Air-oven aging, hot pressure, heat shock, loss of mass, low-temperature tests and weathering where applicable |
| Processing focus | Concentric wall, stable diameter, conductor adhesion and stripping window | Surface finish, print quality, dimensional stability and resistance to die build-up |
An insulation grade should not be relabeled as a sheath grade without documented qualification. The same applies in the other direction. Material color and hardness may look acceptable while the electrical or aging results fail the intended cable standard.
What 70°C and 90°C grades mean
The 70°C or 90°C label normally refers to the temperature class permitted by a particular cable construction and standard. It does not mean the extruder barrel temperature, ambient installation temperature or short-circuit temperature.
| Item | 70°C grade | 90°C grade |
|---|---|---|
| Intended meaning | Compound intended for a cable construction whose governing document permits a 70°C conductor temperature in normal service | Heat-resistant compound intended for a cable construction whose governing document permits a 90°C conductor temperature in normal service |
| Approval basis | Exact compound designation, cable standard and completed tests | Exact heat-resistant designation, cable standard and completed tests |
| Can it be inferred from hardness? | No | No |
| Can it be inferred from extrusion temperature? | No | No |
| Can the finished cable claim the rating from the compound alone? | No | No |
Many general PVC building-wire and flexible-cord constructions use a 70°C maximum conductor temperature in normal service. Some heat-resistant flexible-cord constructions allow 90°C. The exact designation and limits must come from the edition of the cable standard named in the order.
IEC, EN, BS, UL and CSA systems do not use one universal compound code. Do not treat labels such as PVC/C, TI 1, TM 1, PVC/A or a supplier’s J-70 code as automatic equivalents. Record the designation required by the finished-cable standard and keep the supplier’s internal grade code as a separate field.
A 90°C compound also does not convert an existing 70°C cable into a 90°C cable. The conductor, insulation thickness, sheath, assembly, terminals, installation method and finished-cable tests must support the higher rating.
Hardness needs a method, not only a Shore number
Hardness affects flexibility, handling, stripping and resistance to deformation, but a value such as “Shore A 70” is incomplete by itself.
ISO 868 uses a Type A durometer for softer plastics and a Type D durometer for harder plastics. The result is an empirical indentation measurement used mainly for control. A purchase specification should record:
- Shore scale, such as Shore A or Shore D
- Test method and edition
- Specimen preparation and thickness
- Conditioning temperature and time
- Initial or delayed reading time
- Target and tolerance
- Result reported for the approved sample and production lot
Hardness should not replace tensile, elongation or electrical tests. Two PVC cable compounds can have similar Shore A readings and still behave differently during extrusion, stripping or heat aging.
Electrical, mechanical and aging data to verify
Use the test method required by the governing material or cable standard. Where the buyer adds a separate material test, the method, specimen and test conditions must be written into the specification.
| Property | What the report should show | Why the test conditions matter |
|---|---|---|
| Volume resistivity | Result, unit, test voltage, test temperature, conditioning and method | Resistivity changes with temperature, moisture, specimen preparation and electrode arrangement |
| Dielectric strength | Result, unit, specimen thickness, electrode system, medium and voltage rise conditions | A kV/mm value is not comparable if the specimen or method changes |
| Finished-cable voltage test | Cable construction, test voltage, duration and result | This is a finished-cable check, not a substitute for a compound data sheet |
| Tensile strength before aging | Median or specified result in MPa or N/mm², specimen type and test speed | Specimen preparation and test speed affect the result |
| Elongation at break before aging | Result in percent, specimen type and test speed | A percentage without a method cannot be compared reliably |
| Air-oven aging | Temperature, duration, tensile and elongation after aging, plus variation where required | “Passed aging” has no meaning without the cycle and acceptance criteria |
| Loss of mass | Test temperature, duration, result and acceptance limit | This test is commonly applied to PVC insulation and sheath compounds under IEC 60811-409 |
| Pressure at high temperature | Applied force, temperature, duration and indentation result | The conditions are selected by the applicable cable or compound specification |
| Heat shock | Temperature, duration, specimen preparation and visual result | A pass statement must identify the test conditions |
| Low-temperature behavior | Bend, elongation or impact method, test temperature and result | “Cold resistant” needs a stated test temperature and method |
IEC 60811-501 covers mechanical-property testing for insulation and sheathing compounds. IEC 60811-401 covers aging in an air oven. IEC 60811-409 covers loss of mass for thermoplastic insulation and sheath materials and normally applies to PVC. IEC 60811-508 covers pressure testing at high temperature. These are test methods. The product standard or agreed material specification owns the test conditions and acceptance limits.
For volume resistance and volume resistivity of solid electrical insulating materials, IEC 62631-3-1:2023 provides a general DC method. Use it only when it matches the purchasing specification. A cable standard may call for a different electrical test on the completed insulation or finished cable.
Processing stability must be checked on the intended line
A laboratory data sheet cannot show every production issue. The approved PVC cable compound should also complete an extrusion trial on the line or on a technically comparable line.
Record the following during the trial:
- Compound grade, batch number, color and sample mass
- Extruder make, screw diameter and screw design reference
- Conductor material, conductor size and preheating condition
- Barrel, head and die temperature settings
- Screw speed, line speed, motor load, head pressure and output
- Tooling, insulation or sheath target thickness and cooling arrangement
- Start-up scrap, stable-run length and any unplanned stoppage
- Surface finish, color dispersion, diameter, concentricity and print quality
- Die drool, plate-out, scorching, gels, contamination or odor observed during the run
- Strip force or stripping observation when relevant
- Retained sample ID and finished-cable test results
These are trial records, not universal setpoints. Barrel temperature, screw speed and line speed depend on the formulation, extruder, tooling, wall thickness and cable construction. A supplier should provide a starting processing window in the TDS, then update it from the approved trial.
Sample approval fields
Ask the supplier to identify each sample clearly. “70°C PVC granules” is too broad for approval.
| Sample field | Information to request |
|---|---|
| Supplier and manufacturing site | Legal supplier name and production location |
| Supplier grade code | Exact commercial or internal code |
| Intended layer | Conductor insulation, core insulation, inner sheath or outer sheath |
| Governing standard | Standard number, part, edition and required compound designation |
| Temperature class | 70°C, 90°C or other class stated by the governing cable standard |
| Color | Color name, reference code and tolerance method if required |
| Hardness | Scale, method, target, tolerance and reading conditions |
| Restricted substances | Required declaration or test report, such as the buyer’s RoHS or REACH document list |
| Sample quantity | Mass needed for laboratory plaques, extrusion trial and retained sample |
| Lot identity | Batch or lot number and production date |
| Supplied documents | TDS, safety data sheet, sample test report and compliance declarations |
| Trial target | Cable type, conductor size, layer thickness, line and tests to be completed |
Approve the compound against both the sample data and the extrusion result. Keep a sealed retained sample or other agreed reference so color, pellet appearance and basic processing behavior can be checked if a later lot is disputed.
COA fields for each production lot
A TDS describes the grade. A COA reports the identified production lot. Do not accept a TDS relabeled as a batch certificate.
The COA should contain:
- Supplier name and manufacturing site
- Product name and exact grade code
- Batch or lot number
- Production date and COA issue date
- Order or customer reference where agreed
- Color or color code
- Test property name
- Test method and edition, or a controlled internal method reference
- Specification limit or agreed range
- Actual batch result
- Unit of measurement
- Pass or fail decision
- Authorized approval or electronic release reference
- Traceability to any subcontracted or external test report
At minimum, the COA property list should match the agreed control plan. Hardness, tensile strength, elongation, density, electrical property and thermal-aging indicators should appear only when they are part of that plan and were measured for the stated lot. A supplier should not populate missing tests with typical values from the TDS.
Common applications
PVC insulation compound is used in many fixed-wire and flexible-wire constructions. Examples on the KingForYou Cable site include H07V-U / NYA building wire and TW/THW cable. The exact formulation still depends on the named product standard, conductor class and temperature rating.
PVC sheath compound is used on cable designs that require an extruded protective outer layer. U-1000 R2V/XV/RV cable is one example of a low-voltage cable family in which the sheath specification must be kept separate from the insulation specification.
Control cables, appliance cords and regional building-wire products may also use PVC. Avoid choosing the material from the cable name alone. Confirm the construction layer and the current standard before requesting a sample.
Which document owns each value?
| Document | What it should control |
|---|---|
| Finished-cable standard | Cable construction, voltage designation, material designation, temperature rating and finished-cable tests |
| Buyer specification | Project-specific requirements, approved alternatives, document list and acceptance rules |
| Supplier TDS | Grade identity, intended use, typical properties, specification values where declared and processing guidance |
| Approved sample report | Results for the submitted sample and extrusion trial |
| COA | Lot identity and actual results for the agreed batch-control properties |
| External laboratory report | Results for the identified specimen or cable under the stated method and conditions |
This document hierarchy prevents a common purchasing error: taking a typical value from a brochure and treating it as a guaranteed COA limit.
PVC cable compound RFQ checklist
Send these fields with the request for quotation:
- Finished cable type and intended market
- Cable standard, part and edition
- Required compound designation under that standard
- Insulation, inner sheath or outer sheath use
- Rated voltage and required temperature class
- Conductor material, conductor class and size range
- Target layer thickness or finished cable drawing
- Required color and color tolerance method
- Hardness target with scale and test conditions
- Electrical, mechanical, aging, flame and low-temperature tests required
- Restricted-substance declarations and required test reports
- Sample quantity and extrusion-trial plan
- TDS, safety data sheet and COA template required before approval
- Packaging unit, moisture protection requirement, labeling and lot traceability
- Estimated order quantity and delivery destination
For an existing 70°C insulation product, the PVC compound product page can be used as the start of a discussion. Request the current TDS, test methods, sample data and COA template before treating any website value as a purchasing specification.
FAQ
Is wire compound the same as PVC cable compound?
Wire compound is the broader term. PVC cable compound is one type of wire compound. Other wire and cable compounds include polyethylene, cross-linked polyethylene, low-smoke zero-halogen materials and elastomeric compounds.
Can one PVC compound be used for insulation and sheath?
Only if the grade is documented and approved for both functions under the relevant specifications. Similar color or hardness does not prove suitability.
Does Shore A 70 mean the cable is rated 70°C?
No. Shore A 70 is a hardness statement. A 70°C rating is a thermal class under the applicable cable construction and standard. The numbers describe different properties.
Is a 90°C PVC compound always better than a 70°C compound?
No. It is suitable only when the cable design and standard require or permit that temperature class. Processing, flexibility, stripping behavior, cost and the rest of the cable construction still need approval.
Should a COA show typical values or actual values?
The COA should identify the production lot and report actual results for the properties in the agreed batch-control plan. Typical grade values belong in the TDS.
What should be checked before approving a sample?
Check the grade identity, intended layer, standard designation, temperature class, hardness method, material test report and extrusion trial. Complete the required finished-cable tests before releasing the compound for production.
Request a grade review
Send the cable standard, construction drawing, insulation or sheath use, temperature class, color, required test list and expected order quantity. KingForYou Cable can review the requested grade, prepare a sample plan and confirm the document package before quotation. View the electrical cable product range or contact the team with the RFQ fields above.
