What are the applications of needle flame testers in the electrical industry

Source：www.cshuaqiang.com Release date： 2025-09-09

Needle flame tester is a core equipment used in the electrical industry to evaluate the "flame retardant safety" of products. Its core function is to simulate the "small flame" (i.e. "needle flame") generated inside electrical equipment due to faults (such as line short circuit, component overheating, arc discharge, etc.), detect the combustion characteristics, flame propagation risk, and extinguishing state of materials or components under the action of such local high-temperature flames, and determine whether the product meets the requirements of electrical safety standards for flame retardant performance. Its application in the electrical industry is mainly concentrated in the following major scenarios:
1、 Core application scenario: Testing of "key components and materials" for electrical products
The core objective of needle flame testing is to identify potential fire risk points in electrical products caused by local high temperatures. Therefore, the application scenarios are highly focused on components and materials that come into direct contact with current and are prone to local overheating, including:
1. Testing of insulation materials and insulation components
Insulation materials are crucial for preventing electrical leakage and ensuring safety in electrical equipment. However, when their flame retardant properties are insufficient, they may become the trigger of a fire if they encounter local high temperatures (such as wire overload heating or motor winding short circuit). The needle flame tester is mainly designed for these types of materials/components:
Specific objects: insulation sheath of wires and cables (such as PVC insulation layer, cross-linked polyethylene insulation layer), insulation enameled wire of motors/transformers, insulation shell of electrical switches (such as socket panels, circuit breaker shells), insulation substrate of circuit boards (such as FR-4 epoxy glass cloth substrate), etc.
Test purpose: To verify whether the insulation material will continue to burn under the action of a "needle flame" (simulating a local overheating source), and whether it will produce droplets (droplets may ignite the combustible material below), ensuring that even if small flames appear locally, the insulation material can be quickly extinguished to avoid the spread of flames and the overall fire of the equipment.
2. Testing of materials around electrical connections and current carrying components
Electrical connection points, such as terminal blocks and contact points of plugs and sockets, are high-risk areas for high temperature faults - poor contact can lead to arc discharge, overload can cause metal contacts to overheat, and these high temperatures can easily ignite surrounding non-metallic materials. Needle flame testing should be targeted at materials in high-risk areas such as:
Specific objects: filling insulation materials inside the junction box (such as silicone sealing rings, insulation gaskets), fixed plastic parts inside the plug (such as terminal fixing seats inside the plug housing), plastic bases of relays/contactors (near the contacts), etc.
Test purpose: To confirm the flame retardant ability of these materials under the action of "needle flame" (simulating contact arc or overheating), and prevent the ignition of surrounding materials due to local high temperature, which may cause fires in junction boxes, plugs and other components.
3. Flame retardant performance verification of electronic components and assemblies
Electronic components, especially power components, may generate local high temperatures or small flames during faults, and their own and surrounding components' flame retardancy directly affects equipment safety. Needle flame tester is commonly used for:
Specific objects: shells of capacitors and resistors (such as epoxy resin shells of metal film resistors), plastic shells of LED driving power supplies, solder resist around surface mount components on circuit boards, insulation protective shells of battery packs (such as plastic protective shells of lithium batteries), etc.
Test objective: To investigate the flame risk in the event of component failure - for example, to verify whether the small flame generated when a capacitor breaks down will ignite its own casing or surrounding circuit board, ensuring that a single component failure does not escalate into an overall fire.
2、 Industry standard driven: comply with mandatory requirements of global electrical safety regulations
Needle flame testing is not an optional test, but a mandatory testing item specified in mainstream global electrical safety standards (such as IEC, GB, UL standards). Any electrical product entering the market must pass the corresponding needle flame testing. The essence of this application scenario is "compliance testing", with core coverage of:
International standards such as IEC 60695 (International Electrotechnical Commission standard, covering fire testing methods such as "needle flame test" and "hot wire test"), of which IEC 60695-11-5 specifies the specific process of needle flame testing and is applicable to almost all electrical equipment (such as household appliances, information technology equipment, lighting equipment).
Domestic standard: Chinese GB/T 5169.5 (equivalent to IEC 60695-11-5) is an essential testing item for domestic electrical products (such as refrigerators, washing machines, air conditioners, routers, and lighting fixtures) to obtain "3C certification" (China Compulsory Product Certification).
Regional standards such as EN 60695 from the European Union and UL 94 from the United States (although mainly based on "horizontal/vertical combustion", some electrical products require needle flame testing) are prerequisites for products to enter the EU (CE certification) and US (UL certification) markets.
3、 R&D and Quality Control: Full Lifecycle Security Assurance
In addition to compliance testing, needle flame testers are also deeply applied in the research and development, design, and production quality control of electrical products, achieving flame retardant safety assurance from the source to the finished product
1. R&D stage: material selection and structural optimization
When developing new equipment, it is necessary to compare the flame retardancy of different materials through needle flame testing (such as choosing "V-0 grade" or "V-1 grade" plastic) to ensure that the materials meet the safety requirements of the equipment usage scenario (such as using more flame resistant insulation materials for motors in high-temperature environments).
For equipment structure design (such as component layout and heat dissipation channels), verify through needle flame testing whether the "local fault flame" will be blocked by the structure (such as avoiding flame spread to combustibles through partitions), and optimize the design scheme.
2. Production stage: Batch quality sampling inspection
When mass production is carried out on the production line, it is necessary to regularly extract finished products or key components (such as wires and sockets) for needle flame testing to identify quality issues caused by differences in raw material batches and fluctuations in production processes (such as decreased flame retardancy of plastics due to high injection molding temperatures), in order to prevent unqualified products from entering the market.
3. Fault analysis: Tracing the causes of fire hazards
When electrical products experience fire faults or safety complaints, needle flame testing can be used to simulate the fault scenario and determine whether the flame spread is caused by "substandard material flame retardant performance", "structural design defects of components", or "improper use", providing a basis for fault tracing and product improvement.

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