UL588 light string test in the United States

二、核心测试项目
UL588 的测试围绕 “电气安全”“机械可靠性”“环境耐受性” 三大维度展开，具体项目如下：

1. 电气安全测试

确保灯串在正常及故障状态下无电击、短路风险：




• Insulation resistance test: Measure the insulation resistance between wires, lamp sockets, and metal components to ensure that the insulation material effectively isolates live objects (usually requiring ≥ 100M Ω).

• Dielectric strength (withstand voltage) test: Apply high voltage (such as 1000V AC voltage for 1 minute) between live parts and accessible metal parts without breakdown or flashover.

• Short circuit protection test: Simulate whether the protective devices (such as fuses and current limiting resistors) of the light string can quickly cut off the current and prevent the wires from overheating and catching fire when a single light bulb or wire is short circuited.

• Grounding continuity test (for light strings with grounding): Verify the reliability of the connection between the grounding wire and the grounding terminal, with a grounding resistance of ≤ 0.1 Ω.

2. 机械安全测试

确保灯串结构牢固，使用中不易损坏或产生危险：




• Bending test: Repeatedly bend the wire (such as 3000 times), simulate bending in daily use, and test whether the wire is broken and whether the insulation layer is damaged.

• lightSeat and bulb firmness test: After installing the bulb, apply axial tension (such as 2.2N) to test whether the bulb falls off; The connection between the lamp holder and the wire needs to withstand torque testing without looseness.

• Plug mechanical strength test: After inserting/unplugging the plug into/from the socket 1000 times, check whether the pins are deformed and whether the contact is good; Apply impact to the plug (such as dropping from a specified height) without rupture or functional failure.

• Anti electric shock protection test: Simulate human contact through a probe to verify whether the touchable parts are non charged bodies; Small components such as light bulbs and lamp holder accessories must pass the "Child Swallowing Test" (components with a diameter<31.75mm must meet the anti swallowing requirements).

3. 环境耐受性测试

针对灯串的使用场景（尤其是室外），验证其耐候性：




• Humidity test: After being placed in a high humidity environment (such as 95% relative humidity, 40 ℃) for a specified time, retest the insulation resistance and dielectric strength to ensure that the insulation does not fail in a humid environment.

• Rain test(only outdoor light string): simulate the rainstorm environment, test the electrical safety (such as no short circuit, leakage) after spraying water on the light string, and ensure that the waterproof performance meets the standard when used outdoors.

• Salt spray test (for light strings in coastal or highly corrosive environments): After metal components (such as lamp sockets, connectors) are exposed to salt spray, check for rust or corrosion that may affect electrical connections.

• Flame retardant test: The insulation wires, plastic lamp holders, and other materials of the light string must pass a horizontal combustion test (such as UL94 V-2 or higher), and self extinguish within 30 seconds after removing the open flame to prevent the spread of fire.

4. 特殊场景测试

• Series test: When multiple sets of light strings are used in series (such as when the user connects 5 sets of light strings), test whether the overall current, temperature rise, and short circuit protection still meet the requirements to avoid overload.

• Light bulb replacement test: After using a replacement light bulb that meets the specifications (such as different power and type), test whether the light string can still operate safely (such as no overheating or short circuit).

三、标识与说明书要求

说明书：需包含安装指南（如最大串联数量）、维护要求（如替换灯泡的规格）、安全警告（如远离水或热源）。

四、工厂检查要求