DSH 492 Protection against access to live parts

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DSH 492

Protection against access to live parts 4 x9 ~) R+ R+ x" ^* m! Y( x, m. W" V

8.1.4 5 l5 v5 G! ^+ `

60335-1(ed.3) $ P# \% W/ O1 |8 |' ?2 D

Standard: IEC 60335-1:1991, 3rd Ed.
Sub clause: 8.1.4
Sheet No. DSH-492
, p2 [. c) ^3 d( [% r# W( fSubject: Protection against access to live parts
3 x$ |- S) L4 j  @' aKey words: - Functional earthing
Decision taken at 40th CTL meeting 2003
Question:
Is functional earthing for the secondary circuit of SELV transformers permitted?
Rationale:
' A( J& F; t  x8 T8 M6 VSee question.
Decision:
; p0 @2 E4 l- u, G. C4 k9 ]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
if:
a) the accessible parts of the secondary circuits are separated from the protective earthing
circuit by at least protective impedance, or
) ?- U; V1 m" Q) z" x$ y7 @b) the accessible parts of the secondary circuits are either directly connected to the protective
3 _+ ]  V1 N5 `# r9 K) t, S1 Fearthing circuit or are protected against accidental contact by insulation as specified for Class
; }" R2 u  ~0 W3 q' C. z  I/ tIII appliances or constructions, in particular the insulation shall be capable of withstanding a
test voltage of 500 V AC for 1 min.
7 B# A2 w) H5 z5 L/ ?% S/ MAccessible parts directly connected to the protective earthing circuit shall comply with the
( ]( u/ K9 o# ^7 [; K- P, _- Hrequirements for protective earthing (see sub-clause 27.5) or shall be separated from live
/ F( `! y- l9 F' J/ ]parts of the supply with insulation as specified for Class II construction.
2. See also the following figure.
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