EN 50497 Assessment of the Risk of Plasticizer Leakage from PVC Insulated and Sheathed Cables

The European standard “EN 50497 Recommended test method for assessing the risk of plasticizer leakage from PVC insulated and sheathed cables” demonstrates the leakage of plasticizer from PVC insulated and sheathed cables individually using an accelerated test. This method is designed for use where the manufacturer identifies a specific risk that cannot be assessed solely by the conformity test described in EN 60811-1-2. This method is designed as a qualitative test on the finished product and not as an individual material test.

While any leaching is most likely plasticizer, other components may also leach and are treated equally in this test for the purposes of this standard. The method was specifically developed for PVC/PVC cables. No recommendations are given regarding its use with cables based on other insulation and sheath materials.

For the purposes of this standard, the following terms and definitions apply:

• Compatibility: This refers to the ability of a plasticizer to be held by the parent compound or base resin. High compatibility indicates good adhesion by the parent compound.
• Plasticizer: A substance added to a material to increase its flexibility, softness, stretchability, or processability. Plasticizers typically consist of oily, organic liquids with high boiling points.
• Leakage: The visible presence of plasticizer on the cable surface or dripping from the cable.
• Operating temperature: This is the maximum allowable conductive temperature of the finished product.

For testing, two representative samples are taken from the finished cable. The cable is cut into two test samples, each approximately 200 mm long plus/minus 10 mm. If a manufacturer produces the entire range of a product to a specific standard, and the same materials are used, then testing only one representative size is sufficient.

Test samples must be conditioned at 23 degrees plus/minus 2 degrees for 24 hours prior to testing.

Two conditioned test specimens are hung vertically in an air oven with filter paper placed underneath them. The bottom edge of each specimen should be 15 mm plus/minus 5 mm above the filter paper. The test specimens are hung in the air oven for 7 days at a temperature 10 degrees above the maximum permissible conductor temperature of the cable, but at a minimum of 80 degrees plus/minus 2 degrees. Immediately following this 7-day period in the air oven, the test specimens are separated as follows:

• A test sample is kept at an ambient temperature of 23 degrees plus/minus 2 degrees.
• A test sample is kept at minus 5 degrees plus/minus 2 degrees.

In both cases, the test specimen, suspended vertically with filter paper placed underneath at the previously described distance, is kept under the relevant conditions for 21 days. The test specimens are checked at regular intervals for signs of plasticizer leaching for 28 days (7 days + 21 days).

When evaluating the results, inspection for plasticizer leakage should be performed without magnification, using normal or corrected vision. The following should not be present:

• An oily film on the cable surface.
• Droplets at cable ends
• Traces on the filter paper.

The EN 50497 standard provides a recommended test method for assessing the risk of plasticizer migration (leakage) from PVC-insulated and PVC-sheathed cables and cords. Plasticizer leakage can cause cables to become sticky, attract dust, or lead to performance and aesthetic problems over time, especially in emergency or safety-critical circuits.

This standard applies to PVC insulated and PVC sheathed cables designed with natural fire resistance. It is particularly important for cables used in emergency circuits (e.g., fire alarms, emergency lighting, and evacuation systems). The described method is an accelerated testing method aimed at predicting long-term behavior related to plasticizer degradation.

This method,

• This involves exposing cable samples to specific temperature and time conditions to accelerate potential plasticizer migration.
• It includes visual and tactile assessment for signs of oily or sticky residue (exudation) on the surface.
• It helps manufacturers and users evaluate whether a cable formulation is suitable for applications where surface cleanliness and long-term stability are important.

PVC (polyvinyl chloride) is widely used in cable insulation and sheathing due to its flexibility, flame retardancy, and cost-effectiveness. However, PVC requires plasticizers (e.g., phthalates) to achieve the desired flexibility. Under certain conditions (heat, time, incompatible materials), these plasticizers can migrate to the surface (a phenomenon known as exudation or sweating).

The EN 50497 standard helps reduce risks in safety-related installations by providing a standardized way to test and qualify cables. It is often mentioned in conjunction with other fire-related cable standards (such as the EN 50200 or EN 50525 series of standards).

The EN 50497 standard provides a recommended test method for evaluating plasticizer migration (leakage) from PVC-sheathed cables and cords. Plasticizer leakage can cause cables to become sticky, attract dust, or lead to sustained performance and aesthetic issues, particularly in emergency or safety-critical circuits.

The main reasons why the EN 50497 standard is considered important are as follows:

• Prevents cable material degradation: PVC cable components contain plasticizers to maintain flexibility. Under certain installation or environmental conditions, these plasticizers can migrate out of the cable material. This alters the physical properties of the PVC over time, making it harder, more brittle, and more prone to cracking.
• Improves electrical safety: Plasticizer leakage can degrade insulation quality and damage adjacent cable components or nearby materials. In severe cases, this can lead to insulation failure, reduced service life, or electrical hazards. This standard helps manufacturers identify these risks early through accelerated aging conditions.
• Supports long-term reliability: This standard simulates long-term service conditions using high temperatures and conditioning times. This allows manufacturers to verify that finished cables remain stable during storage and operation. Reliable cables are particularly important in buildings, industrial facilities, automotive systems, and infrastructure projects.
• It identifies problems that cannot be found with compatibility tests: This standard is designed for situations where the normal compatibility test in the EN 60811-1-2 standard may not fully reveal the risk of leakage. It serves as an additional qualification tool when manufacturers suspect unusual material interactions or challenging installation conditions.
• It is beneficial for quality assurance and product qualification: Cable manufacturers, testing laboratories, and certification bodies use the EN 50497 standard in the following situations:
  • Product development
  • Material selection
  • Supplier qualification
  • Final product verification
  • Addressing field complaints.

The test is performed not only on the raw materials but also on the finished cable product, which makes it more representative of real-world service behavior.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the EN 50497 standard.