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24 Electrical Spacings$ o* d8 f8 s3 K3 Q9 G( m
24.1 The spacing between uninsulated live parts of opposite polarity, and between uninsulated live parts
) a5 O" Z* \+ band metal that is capable of being grounded shall not be less than 1/4 inch (6.4 mm) through air or 3/87 D/ \! g6 g" Q1 y: m; |% Y
inch (9.5 mm) over surface. The outer wrap of an open core and coil ballast is determined to be an5 B! R* X2 X1 k; Z2 r, s2 J, z- y
uninsulated live part with respect to this requirement.7 f D) Z9 Q6 {
Exception No. 1: The spacing requirements do not apply between uninsulated live parts of a wiring device, f7 z* @5 F) }/ W8 Y
such as a lampholder or switch, and dead metal that is part of the wiring device and including mounting5 i2 G6 f1 S0 m. u
screws, rivets, yoke, clamp, or similar components; or for a portable luminaire provided with a grounding/ \: x9 x- a9 ^5 w. Y, I' g
means between such live parts and that part of the dead metal surface of the portable luminaire on which& G9 w: R4 c/ u# ~; ]
the device is mounted in its intended manner. See Figure 24.1.) ^* x; A' d) J1 w$ m$ l/ t, d
Exception No. 2: When an isolated dead metal part is interposed between or is in close proximity to:
& ~9 |9 k, ]3 _' a. u+ W- a% ga) Live parts of opposite polarity;, A( g/ D. [$ H: t; f
b) A live part and an exposed dead metal part; or% l0 t( z. Z1 ^1 \! F5 s
c) A live part and a dead metal part that is able to be grounded, the spacing shall not be less/ C3 ~0 k. I& T3 `# m$ m
than 3/64 inch (1.2 mm) between the isolated dead metal part and any one of the other parts% l% J5 w. t7 @" V) _/ A
previously mentioned, provided the total spacing between the isolated dead metal part and the( n5 N' r, u C, S, z
two other parts is not less than 1/4 inch (6.4 mm) through air or 3/8 inch (9.5 mm) over surface. p8 s8 e+ m, `1 A
Exception No. 3: The spacing between uninsulated live parts of a Class 2 circuit and between such parts9 y6 R. M0 `5 }' Y& h
and dead metal that is grounded in service is not specified.4 b8 j4 d' F% \, G: f+ C: U
. z# v8 t Q- K& L: Y! P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？
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发表于 2015-2-13 11:13
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