DSH 492 Protection against access to live parts

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广东安规检测
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DSH 492

Protection against access to live parts 7 N4 o" c  q5 _  S

8.1.4 ' i7 a, A" o  N4 N8 Z

60335-1(ed.3)

Standard: IEC 60335-1:1991, 3rd Ed.
1 ], |, N% V7 H# fSub clause: 8.1.4
Sheet No. DSH-492
Subject: Protection against access to live parts
Key words: - Functional earthing
1 Y+ s6 j0 \- v7 s) rDecision taken at 40th CTL meeting 2003
  A$ z2 z; `/ P3 L) j" E3 m! JQuestion:
2 r" t) @/ z3 Z: N/ AIs functional earthing for the secondary circuit of SELV transformers permitted?
) h4 f8 d. F# ORationale:
2 c" q2 ?. X, D; g0 G9 fSee question.
Decision:
1) Earthing of secondary circuits of SELV transformers (PELV circuits) is acceptable in
general except when SELV is specifically required by the standard for a specific circuit (for
example in whirlpool baths), in which case earthing of the secondary circuits are acceptable
$ w0 R$ l8 s2 @( N, qif:
a) the accessible parts of the secondary circuits are separated from the protective earthing
9 d; f$ [; {; R7 z. [  N2 Fcircuit by at least protective impedance, or
b) the accessible parts of the secondary circuits are either directly connected to the protective
% R1 A8 H6 B$ I8 Jearthing circuit or are protected against accidental contact by insulation as specified for Class
5 K7 a# m7 P6 \7 G1 k, a/ R1 y- h! }III appliances or constructions, in particular the insulation shall be capable of withstanding a
3 i6 k0 Q2 F. rtest voltage of 500 V AC for 1 min.
: O! ^5 N' P2 U! v. z! {; k: JAccessible parts directly connected to the protective earthing circuit shall comply with the
- H" X" D% J; J$ crequirements for protective earthing (see sub-clause 27.5) or shall be separated from live
parts of the supply with insulation as specified for Class II construction.
2. See also the following figure.
+ A+ D; f4 O# i


$ B2 v; Z. Z* {5 b