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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) P8 H5 h. Q% O$ M" E
mm) between uninsulated live parts of opposite polarity; and between a rigidly mounted uninsulated live
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Exception No. 1: If exact centering of the cold pin of a sheathed-type heating element is required to- Y; q, K4 h0 h1 h! u: k$ d4 q
maintain the 1/16 inch (1.6 mm) spacing, a spacing of 3/64 inch (1.2 mm) in one location is acceptable.# Y8 k8 ^ f8 q4 M& [7 L
Exception No. 2: Spacings in an appliance that comply with 21.1.2 need not comply with 21.1.1.
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21.1.2 At closed-in points only, such as the screw-and-washer construction of an insulated terminal/ Z' K: v) ?4 O& B9 h& c
mounted in metal, a spacing of 3/64 inch (1.2 mm) is acceptable. Within a thermostat, except at contacts,
9 q0 Z& W* \' ?2 r7 n+ f7 Gthe spacings between uninsulated live parts on opposite sides of the contacts shall not be less than 1/32* [& D% t7 S4 i1 V; K; t5 e! M% Q- q
inch (0.8 mm) through air and 3/64 inch (1.2 mm) over the surface of insulating material, and the, V3 x' v, E. G2 Q/ Q1 Y9 [
construction shall be such that the spacings are maintained permanently.
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a. 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?2 [' } A% f M4 M
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b. 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?- } c, K% y; b+ y2 ^2 l
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