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LZ说的要求其实在标准当中是来源于7.2.1的这段话:4 q+ ~3 S# T T( g% y) P p
Metal parts of luminaires which may become live in the event of an insulation fault and which
: j2 O/ v j7 i" i1 ?are not accessible when the luminaire has been mounted, but are liable to come into contact
) x* `; j8 E" Y9 Y7 e9 ?with the supporting surface, shall be permanently and reliably connected to an earthing2 ?! l+ k; i$ e! Y* Z3 X
terminal.7 P* g. P& T1 p6 \# P
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所以问题的关键在于以下两点:
. K3 u$ j- l8 z0 F5 V/ v2 B7 \1、灯具内部的基本绝缘部件会不会与金属支架接触。如果是不可能接触到灯具内部的基本绝缘件,那么其实支架无需接地;
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! O+ J' C# P/ c$ o: c$ |7 [9 z2、如果考虑了上述第一点判断支架需要接地,那么是否可以认为安装螺钉+菊花垫片提供了可靠的接地呢?我的理解是要考虑三方面:
% H+ \8 R. }6 Z/ e5 j* ~2 g 2.1 接地电阻测试;
+ o! V. c/ A/ W! j. }' U0 f: Q+ B) n 2.2 满足4.11.3的要求(这里有菊花垫片,可以认为满足了4.11.3的要求); / N1 O* L% n3 _% S
2.3 在7.2.1要求‘permanently’永久地连接到接地端子(那么很多机构会认为固定支架的螺钉在安装过程中需要拆装,一次不是一个永久的接地连接。其实这也是合理的,因为你无法保证灯具经过安装后,支架和灯外壳之间还能保持良好的接地连接)
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至于楼上提及的金属外壳是喷漆或者电镀的其实不是关键,标准当中另有条款规定了:( k) F9 E" h1 m1 R* C9 ?
7.2.8 Either the screw or the other part of the earth terminal shall be made of brass or other
- j, d0 V [( Qnon-rusting metal or a material with a non-rusting surface and the contact surfaces shall be
4 F: P+ s0 Y0 J: ^/ Qbare metal.
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