标准更新背景
2022年1月，美国纽约布朗克斯发生一起因便携式电暖器引发的高层住宅火灾，造成19人死亡（包括9名儿童），成为美国近几十年来最严重的住宅火灾之一。
美国消费品安全委员会（CPSC）因此启动了专项调查，评估市场上的电暖器产品，并分析了2011年至2022年间的2345起相关事故报告。
主要发现：
安全隐患
电暖器电源线组内部与插头连接不良，可能导致过热甚至起火。
产品内部连接不牢固，可能引发塑料部件燃烧。
使用可燃塑料材料的电暖器存在持续燃烧风险。
不当使用电源线延长线是导致火灾的常见因素。
产品结构与认证问题
获得UL认证的产品整体结构更安全，性能更稳定。
未认证产品存在更多结构缺陷，如焊接不良、使用易燃塑料等。
美国消费品安全委员会(CPSC)要求UL公司成立工作组进行审查、制定和改进标准中关于电暖器安全性的规定，并针对UL 1278标准提出修订建议。目前，新的标准版本已经出版，标准更新内容详见附页。
UL 1278标准更新
(第4版，2025年5月29日更新)
本标准的新要求，总结如下：
防倾倒与翻转保护
(4.9.5、33.19、40.1.15、42.4A、42.4B)
|
要点 |
现行/建议要求 |
|
配置要求 |
移动式取暖器必须配备倾倒开关；壁挂/吊装机型及额定208V以上的机型可豁免 |
|
功能 |
一旦检测到机器不在正常工作姿态，应切断全部加热元件，且复位前不得再次加热 |
|
测试方法 |
倾倒测试（42.4A）：通电状态下，按规定方向依次倾倒，倾倒开关须在到达最终静止位置前断开加热 翻转测试（42.4B）：将设备180°倒置后，加热元件必须立即断电 |
阻燃材料要求
(12.1A、12.3、12.4)
|
部位 |
最低阻燃等级 |
|
内部非金属隔板 |
不得用HB等级材料；必须≥V-0、VTM-0、HF-1或SC-0、SCTC-0 |
|
塑料外壳整体 |
遵循第7节外壳要求 (min. V-0) |
|
外壳外部的非金属件 |
至少V-2等级 |
|
例外1 |
若部件远离通风口（≥20mm上方或≥5mm侧/下方），且不会传播火焰，且通过12mm火焰测试 |
|
例外2 |
体积≤2cm³且最长边≤3cm，并且位置不会传播火焰，可放宽至低阻燃等级（需通过12mm火焰或针焰测试） |
内部电气连接
(16D、20.3.4、20.3.5)
|
要点 |
要求/例外 |
|
接线器类型
|
禁止使用旋紧式（twist-on）接线帽作为承载电流的连接件 |
|
内部连接 |
除电源线连接外，其余内部承载额定电流的连接须符合16D.8要求 |
|
功率例外
|
仅承载≤15 W的连接可豁免（需按UL 60730-1 H27.1评估） |
|
功能件例外 |
电机或指示灯的连接可豁免 |
|
电压例外 |
额定208V及以上机型可豁免 |
以下为标准更新部分的正文：
4.9.5 A moveable heater shall employ a tip-over switch. Wall (or ceiling) hung or mounted heaters need not comply with this requirement. Heaters rated 208 V or more need not comply with this requirement.
4.9.5 可移动式取暖器应配备倾倒开关。壁挂式或吊装式取暖器不需遵守此要求。额定电压为208V或以上的取暖器也不需遵守此要求。
33.19 A tip-over switch shall de-energize all the heating elements once detecting the appliance is not in its intended operating position and shall not permit the heating elements to re-energize the heating elements until the appliance is returned to its intended operating position. See 42.4A and 42.4B. A tip-over switch relied on to comply with 42.4A and 42.4B is considered an operating control intended to start or regulate the heater during normal operation. An operating control could provide Type 1 or Type 2 action. (See definitions 3.20 – 3.23).
33.19 倾倒开关在检测到设备不处于其预定工作位置时，应切断所有加热元件的电源，并在设备恢复至预定工作位置之前，不得重新接通加热元件电源。详见42.4A和42.4B。用于满足42.4A和42.4B要求的倾倒开关被视为正常运行期间用于启动或调节取暖器的操作控制器。操作控制器可提供类型1或类型2的动作（定义见3.20–3.23）。
40.1.15 A moveable heater, when tested under the conditions described in 42.4A – 42.4B shall deenergize all the heating elements. The test conditions shall be with different combinations of energized heating elements.
40.1.15 可移动式取暖器在按42.4A–42.4B所述条件进行测试时，应切断所有加热元件的电源。测试应在不同加热元件组合的通电状态下进行。
42.4A.1 A movable heater shall be subjected to 42.4A.2 and 42.4A.3. The heater is to be energized and tested with the different combinations of energized heating elements.
Exception: Wall (or ceiling) hung or mounted heaters need not comply with this requirement. Heaters rated 208 V or more need not comply with this requirement.
42.4A.1 可移动式取暖器应接受42.4A.2和42.4A.3的测试。测试时设备应通电，并在不同加热元件组合下进行。
例外：壁挂式或吊装式取暖器不需遵守此要求；额定电压为208V或以上的取暖器也不需遵守此要求。
42.4A.2 While energized at the rated voltage, the heater shall be tipped over in the manner specified in 42.4A.3. The first tipover is to be onto the front face of the heater and then subsequent tipovers are to proceed in the clockwise or counterclockwise direction at a maximum of 90 degrees direction from the previous tipover direction.
42.4A.2 在额定电压下通电运行时，应按42.4A.3所述方式将取暖器倾倒。第一次倾倒应使设备正面朝下，后续倾倒方向应按顺时针或逆时针方向进行，每次方向变化不超过前一次的90度。
42.4A.3 Each tip over shall be accomplished by tilting the heater to an angle greater than the angle of critical balance. The heater is then to be gradually guided in the path of free fall until the heater comes to its final rest position. The tipover switch device shall de-energize all the heating elements before reaching its final rest position. A tip-over switch device relied upon to disconnect the heating elements for this test is not required to activate prior to the angle of critical balance.
42.4A.3 每次倾倒应将设备倾斜至超过其临界平衡角度，然后沿自由落体路径缓慢引导至最终静止位置。在设备到达最终静止位置之前，倾倒开关应切断所有加热元件电源。用于此测试的倾倒开关不要求在达到临界平衡角之前动作。
42.4B Inversion test
42.4B.1 A movable heater shall be subjected to 42.4B.2. The heater is to be energized and tested with the different combinations of energized heating elements.
Exception: A location-dedicated heater of 3.16 need not comply with this requirement. Heaters rated 208 V or more need not comply with this requirement.
42.4B.1 可移动式取暖器应接受42.4B.2的测试。测试时设备应通电，并在不同加热元件组合下进行。
例外：专用于固定位置的取暖器（见条款3.16）不需遵守此要求；额定电压为208V或以上的取暖器也不需遵守此要求。
42.4B.2 While energized at the rated voltage, the heater shall be inverted 180° from its at-rest position. Immediately after the heater has been inverted, all the heating elements shall de-energize.
42.4B.2 在额定电压下通电运行时，应将取暖器从其静止位置翻转180°。翻转后应立即切断所有加热元件电源。
12.1A Barriers made of non-metallic materials shall have a flammability classification as follows:
a)
The barrier material shall not be a flammability classification HB. The alternate path of Section 5 of UL 746C is not applicable; and
b)
One of the following:
1)
A minimum of V-0, VTM-0, or HF-1, in accordance with Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, UL 94, and IEC Test Flames 60695-11-10; or
2)
a minimum of SC-0 or SCTC-0, in accordance with Tests for Flammability of Small Polymeric Component Materials, UL 1694.
12.1A 非金属隔板的阻燃等级要求如下：
a)
隔板材料不得为HB阻燃等级。UL 746C第5节中的替代路径不适用；
b)
必须满足以下任一要求：
1)
至少为V-0、VTM-0或HF-1阻燃等级（依据UL 94和IEC 60695-11-10的塑料材料阻燃测试）；
2)
至少为SC-0或SCTC-0阻燃等级（依据UL 1694的小型聚合物部件阻燃测试）。
12.3 iEnclosures shall be subject to the requirements in Section 7.
12.3 外壳应符合第7节的相关要求。
12.4 Any non-metallic part external to the external enclosure shall have a minimum flammability classification of V-2.
Exception 1: The part is permitted to be a minimum flammability classification of HB as follows:
a)
Greater than 20 mm above any openings in the enclosure used for venting, air inlet, or air outlet, or greater than 5 mm from the sides or bottom of any openings in the enclosure used for venting,
air inlet, or air outlet; and
b)
Located so it cannot propagate flame from one area to another or bridge between a possible source of ignition and other ignitable parts in accordance with the Standard for Polymeric Materials – Use in Electrical Equipment Evaluations, UL 746C, 50 Flammability – 12 mm Flame Test.
Exception 2: The part is not required to be made of a material classed 5VA, 5VB, V-0, or V-1, if it meets the
following:
a)
The part does not occupy a volume greater than 2 cubic centimeters (0.122 cubic inch), does not have any dimension greater than 3 cm (1.18 inch)i; and
b)
Located so it cannot propagate flame from one area to another or bridge between a possible
source of ignition and other ignitable parts in accordance with the Standard for Polymeric Materials – Use in Electrical Equipment Evaluations, UL 746C, 50 Flammability – 12 mm Flame Test or IEC 60695-11-5 Test flames – Needle-flame test method.
12.4 外壳外部的任何非金属部件应至少为V-2阻燃等级。
例外1：若部件满足以下条件，可为HB阻燃等级：
a)
位于外壳通风口、进风口或出风口上方20mm以上，或侧面/底部5mm以上；
b)
其位置不会导致火焰从一个区域传播至另一个区域，或在潜在点火源与其他可燃部件之间形成桥接（依据UL 746C第50节的12mm火焰测试）。
例外2：若部件满足以下条件，则不要求为5VA、5VB、V-0或V-1等级材料：
a)
体积不超过2立方厘米（0.122立方英寸），且任一尺寸不超过3厘米（1.18英寸）；
b)
其位置不会导致火焰传播或桥接（依据UL 746C第50节的12mm火焰测试或IEC 60695-11-5的针焰测试）。
20.3.4 Twist-on wire connectors shall not be permitted for connections of the wiring in a heater.
Exception: This requirement is not applicable to connections that carry 15 watts or less. The 15 W determinations shall be in accordance with Section H27.1 of UL 60730-1 (or IEC 60730-1).
20.3.4 禁止在取暖器内部接线中使用旋紧式接线器（twist-on wire connectors）。
例外：承载功率不超过15瓦的连接可豁免，15瓦功率评估应依据UL 60730-1（或IEC 60730-1）第H27.1节。
20.3.5 All internal connections of the internal wiring of a heater, except for supply cord connections, shall comply with 16D.8.
Exception 1: This requirement is not applicable to internal connections carrying 15 watts or less in a steady-state condition. The 15 W determinations shall be in accordance with Section H27.1 of UL 60730-1 (or IEC 60730-1).
Exception 2: This requirement is not applicable to connections to a motor or pilot light.
Exception 3: Heaters rated 208 V or more need not comply with this requirement.
20.3.5 除电源线连接外，取暖器内部所有接线连接应符合16D.8的要求。
例外1：稳态条件下承载功率不超过15瓦的连接可豁免（计算依据UL 60730-1第 H27.1节）；
例外2：连接至电机或指示灯的接线可豁免；
例外3：额定电压为208V或以上的取暖器可豁免。
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