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21.1.1 The spacings through air and over surface in an appliance shall not be less than 1/16 inch (1.6
% p# K6 a+ M- r1 E+ B( ~mm) between uninsulated live parts of opposite polarity; and between a rigidly mounted uninsulated live
: N3 _% V! Z6 Q3 m! c! ^/ u5 c. Fpart and a dead metal part that either is exposed for persons to contact or may be grounded.3 f. b' M: n- b
Exception No. 1: If exact centering of the cold pin of a sheathed-type heating element is required to$ t& [' `* A. j" g" [! f
maintain the 1/16 inch (1.6 mm) spacing, a spacing of 3/64 inch (1.2 mm) in one location is acceptable.
$ v1 P7 n2 a5 f: @; NException No. 2: Spacings in an appliance that comply with 21.1.2 need not comply with 21.1.1. @/ X5 G0 p4 F& f5 Y: y y* P
' [4 f3 q5 C1 k* f21.1.2 At closed-in points only, such as the screw-and-washer construction of an insulated terminal I h1 L" }6 w6 ^! |" u
mounted in metal, a spacing of 3/64 inch (1.2 mm) is acceptable. Within a thermostat, except at contacts,4 O2 A+ K8 C0 `
the spacings between uninsulated live parts on opposite sides of the contacts shall not be less than 1/32' I" |; D6 {4 q5 Z N, q% I
inch (0.8 mm) through air and 3/64 inch (1.2 mm) over the surface of insulating material, and the( Y+ E2 Q$ g5 Y1 Z$ F* Q
construction shall be such that the spacings are maintained permanently.
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4 X, `: _8 G1 _- ha. 21.1.1 中例外1,发热管里面有发热丝然后通过焊接一段延长出去(COLD PIN), 一般是圆柱体,EXACT centering 即COLD Pin 圆柱体中心,发热管有两端,意味着有两个cold pin, 这两个cold pin 圆柱体中心距离要求1.6mm, 后面说在一个位置可以有1.2mm 距离,什么叫一个位置(in one location)? 指的是那儿距离可以使1.2mm?+ g9 \' B! l/ l' X W
8 z" E; r2 Z" d9 h4 ^. R8 Tb. 21.1.2, except at contacts, contacts这里是指温控器里面的触点吗?还是指温控器端子引脚? 视乎是端子引脚对吧? 也就是说端子引脚要有1.6mm 电气间隙和爬电距离。然后说温控器两端子引脚间电气连接暴露导体可以是0.8mm 间隙,1.2mm 爬电?对吗? 什么样的结构是认为maintained permanently?4 v7 F0 ` T8 _ {% N% c
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