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|  DSH 492! ] O* T' p3 z
5 R; a$ K% j; Y7 j, X5 g1 ? | Protection against access to live parts3 f' c* G( y- }3 @, J; G( |! ]
| 8.1.48 J6 L! X- M$ @/ C7 V2 h5 s5 F
| 60335-1(ed.3)
8 I- [7 T- N9 c( M* @# o' `/ G |
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Standard: IEC 60335-1:1991, 3rd Ed.
; A% y- C* j$ D( C6 XSub clause: 8.1.4- B! v: Z0 {) D4 X. [0 H
Sheet No. DSH-492
7 `7 I; U$ e/ x& Q* x! z$ P. bSubject: Protection against access to live parts
/ G3 D" F2 V* H& Z. K# eKey words: - Functional earthing! _0 f' Y r9 J n/ _" K* g z
Decision taken at 40th CTL meeting 2003# G, j: Q# j! K: ]$ O
Question:
3 }- u0 d8 f8 b5 U* R4 ^0 ?% G3 YIs functional earthing for the secondary circuit of SELV transformers permitted?
. ]4 f( R: E- S% m. B! g4 GRationale:
4 O* d5 `% {5 u1 c" ASee question.1 a; e+ `7 C+ n
Decision:
( v9 q( z9 y- I2 w1) Earthing of secondary circuits of SELV transformers (PELV circuits) is acceptable in
) C/ E1 {, T R3 x* mgeneral except when SELV is specifically required by the standard for a specific circuit (for
" ~! `! d. @! I: jexample in whirlpool baths), in which case earthing of the secondary circuits are acceptable0 L7 p: a5 H- j9 T+ l& A9 [& f% n( |. c) D
if:
2 a0 w8 X" } qa) the accessible parts of the secondary circuits are separated from the protective earthing7 I0 p0 F7 F$ p3 V0 H4 z, q; R, |$ }& b
circuit by at least protective impedance, or I/ d* c$ H/ A6 a
b) the accessible parts of the secondary circuits are either directly connected to the protective
% X$ t$ _3 U, h6 ?* Jearthing circuit or are protected against accidental contact by insulation as specified for Class9 ?# X% H6 m* t1 y7 @: m; ~% j
III appliances or constructions, in particular the insulation shall be capable of withstanding a
( k \/ Z% T6 m$ T1 e* I3 ntest voltage of 500 V AC for 1 min.; t/ i# p& d+ p4 |
Accessible parts directly connected to the protective earthing circuit shall comply with the
3 ~8 ^3 D& d$ O# X0 \requirements for protective earthing (see sub-clause 27.5) or shall be separated from live
$ \. H& Q9 [+ o& m( Z& jparts of the supply with insulation as specified for Class II construction.7 ` P8 w$ [5 O( y
2. See also the following figure.0 j+ C. t* \/ Q* D
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