Small Test Probe SM390 of UL 498 Figure 139.1

Small Test Probe SM390 of UL 498 Figure 139.1 manufactured in strict compliance with UL 498 Figure 139.1 standard, specially designed for verifying the structural integrity and dimensional accuracy of plugs and sockets. It is engineered to meet all the technical requirements specified in the relevant standard, with its material selection, hardness performance and dimensional tolerances all reaching industry-leading benchmarks. The probe features a small thermal expansion coefficient, which ensures stable and reliable dimensional performance in different working environments, making it a core tool for manufacturers, testing institutions and related enterprises to conduct compliance testing and quality control on plug and socket products, and effectively helping to ensure that the tested products meet the safety and quality requirements of UL 498 standard.

Specifications
• Complies with UL 498 Figure 139.1 standard requirements
• Made of high-quality tool steel for excellent durability and testing precision
• Material hardness ranges from Rockwell C58 to C60 (no less than 50HRC)
• Probe diameter is 0.031±0.002 inches (0.787±0.051 mm) with a 0.002-inch corner radius
• Overall probe length is 2.00±0.010 inches (50.8±0.25 mm) with strict dimensional tolerances
• Features a small thermal expansion coefficient to maintain stable dimensions during testing
• Surface roughness meets the specified indicators of the relevant standard
• Dimensional and tolerance parameters remain reliable during long-term use

Test Procedures
• Prepare the small test probe and the plugs or sockets to be inspected, and ensure that both the tool and the tested products are clean, free of deformation, dirt or other defects that may interfere with test results.
• Refer to the operation guidelines of UL 498 Figure 139.1 to accurately align the probe with the target detection position of the plug or socket (such as small gaps or structural joints).
• Gently insert or place the probe into the corresponding position of the tested product, and check whether the structure and size of the product meet the standard requirements through the probe’s fit condition and contact feedback.
• Record all test data, including the fit status of the probe and the dimensional compliance of the tested position, and make a clear judgment on whether the product conforms to UL 498 standard.
• After completing the test, clean the probe with a professional cleaning tool to remove surface dust or debris, and store it in a dedicated protective container to prevent damage and ensure the accuracy of subsequent tests.

Applications
• Dimensional and structural compliance testing for plug and socket products during the production line quality inspection process in electrical component manufacturing plants
• Quality verification of plug and socket accessories in the electronics and electrical appliance manufacturing industries
• Compliance certification testing of electrical connection devices for third-party testing and certification institutions
• Structural design validation for new plug and socket products in the R&D phase of electrical equipment enterprises
• Routine safety and quality inspection of plug and socket components in the maintenance and upgrade of electrical systems for construction and engineering projects

Small Test Probe SM390 of UL 498 Figure 139.1