DSH 492 Protection against access to live parts

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DSH 492 0 K7 u9 h2 U5 {' m5 d9 y- a

Protection against access to live parts # c( P0 Q  W$ n6 f8 Z8 H

8.1.4 ' D( s1 N4 S9 g* h' ^( I: `2 r

60335-1(ed.3)

Standard: IEC 60335-1:1991, 3rd Ed.
Sub clause: 8.1.4
Sheet No. DSH-492
Subject: Protection against access to live parts
0 |; L" S) J, u, V, Q8 BKey words: - Functional earthing
+ a) w; G$ [3 i+ _. L! hDecision taken at 40th CTL meeting 2003
Question:
4 Q& p; X. o% pIs functional earthing for the secondary circuit of SELV transformers permitted?
Rationale:
See question.
9 {* C  T; j/ M/ Q6 yDecision:
1) Earthing of secondary circuits of SELV transformers (PELV circuits) is acceptable in
5 p; i: F: p/ R  c1 E" F( ggeneral 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
2 j  A8 T: H: G9 x' L; `if:
a) the accessible parts of the secondary circuits are separated from the protective earthing
circuit by at least protective impedance, or
  A% y# u& a' ]8 ?0 B8 B/ O3 eb) the accessible parts of the secondary circuits are either directly connected to the protective
; x* m$ J9 ~# [earthing circuit or are protected against accidental contact by insulation as specified for Class
III appliances or constructions, in particular the insulation shall be capable of withstanding a
test voltage of 500 V AC for 1 min.
) J0 i% g- B" C5 ^6 u" Q, ^1 eAccessible parts directly connected to the protective earthing circuit shall comply with the
: y& V0 Q; V' s% V$ ^) P$ arequirements 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.


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