UL153 带电部件的可触及性

yyrwj · 发表于 2015-2-13 11:13

24 Electrical Spacings
24.1 The spacing between uninsulated live parts of opposite polarity, and between uninsulated live parts
and metal that is capable of being grounded shall not be less than 1/4 inch (6.4 mm) through air or 3/8
inch (9.5 mm) over surface. The outer wrap of an open core and coil ballast is determined to be an
uninsulated live part with respect to this requirement.
Exception No. 1: The spacing requirements do not apply between uninsulated live parts of a wiring device,
such as a lampholder or switch, and dead metal that is part of the wiring device and including mounting
screws, rivets, yoke, clamp, or similar components; or for a portable luminaire provided with a grounding
means between such live parts and that part of the dead metal surface of the portable luminaire on which
the device is mounted in its intended manner. See Figure 24.1.
Exception No. 2: When an isolated dead metal part is interposed between or is in close proximity to:
a) Live parts of opposite polarity;
b) A live part and an exposed dead metal part; or
c) A live part and a dead metal part that is able to be grounded, the spacing shall not be less
than 3/64 inch (1.2 mm) between the isolated dead metal part and any one of the other parts
previously mentioned, provided the total spacing between the isolated dead metal part and the
two other parts is not less than 1/4 inch (6.4 mm) through air or 3/8 inch (9.5 mm) over surface.
Exception No. 3: The spacing between uninsulated live parts of a Class 2 circuit and between such parts
and dead metal that is grounded in service is not specified.

各位大侠，UL153这章的dead metal part,是不是可以直接理解为非金属部件？

Nezof · 发表于 2015-2-13 11:17

是金属部件

yyrwj · 发表于 2015-2-13 11:22

直接理解为金属部件？那前面这个DEAD没意思了？

robin_he · 发表于 2015-2-13 11:27

yyrwj 发表于 2015-2-13 11:22
. R, K: k. T# g& x' n* U0 Y直接理解为金属部件？那前面这个DEAD没意思了？

DEAD是死的，不带电

jsspace · 发表于 2015-2-13 11:32

dead metal part
字面的意思是不带电的金属件
实际上我们可以当成可触及金属外壳

yyrwj · 发表于 2015-2-14 14:11

标准中EXCEPTION NO2中的“A LIVE PART”是指带绝缘的？还是指不带绝缘的？如果不带绝缘的话，极性相反的两极间隔一块不带是电的金属，要是距离很近，这电不会爬过去吗？这标准理解起来好费劲。

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