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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:
" v5 ~& n( j' ^5 _0 N4 c7 MMetal parts of luminaires which may become live in the event of an insulation fault and which
( u$ Z1 m' s. D) i5 ^are not accessible when the luminaire has been mounted, but are liable to come into contact* U3 i2 Q8 n: n1 t
with the supporting surface, shall be permanently and reliably connected to an earthing. O0 X3 H: u4 o( d1 @* X8 }
terminal.
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/ p4 x8 H2 e5 Q5 W% X所以问题的关键在于以下两点:
0 X2 @: k- Q8 B/ X- S- d: [' x1、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;# o ~3 C6 }, j: {- L# B# B! _
' ~6 I0 u" y# L+ G2、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:+ D% j( `9 s1 T. `$ T6 \& K
2.1 接地电阻测试; / {. s: M; n/ t9 v, Q
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); , O% [* p4 A% P/ \
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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; d" O o& ?" I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:2 _. Q+ n8 Q) D0 _ {; ?
7.2.8 Either the screw or the other part of the earth terminal shall be made of brass or other& q9 m E! n" R! ~) |# Y7 m
non-rusting metal or a material with a non-rusting surface and the contact surfaces shall be
' D' z" o& J/ Obare metal.
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