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| DSH 394A
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. Z z/ D; |3 E1 [ | Touch current for equipment having multiple supplies supplying power simultaneously5 r1 a9 H& ]% P6 a' x; A
| 5.1.2, last paragraph / 5.1
1 k; x* {7 O: j& Q% H | 60950-1(ed.1) & 60950(ed.3)
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Standard(s):! u% X; _$ Y; Q' u( D
IEC 60950 (1999) 3rd Ed. }2 v( f' e0 m, z m' m' z6 Y+ O' i
IEC 60950-1 (2001) 1st ed.
% V. [* w! l( |, |+ TSub clause(s):
' `" {% J. }! k3 j& J% U0 h5.1.2, last paragraph
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( u7 t, X" c1 H& _Sheet n°: 394A
, n/ Q- c# o& ]* I% uSubject:
9 A$ D9 S$ U f+ t9 K3 z/ ~TOUCH CURRENT for equipment
; }- Y0 w) ]6 V# jhaving multiple supplies supplying
& O3 X, L( z1 ~$ a' e. A) e4 dpower simultaneously8 L2 A9 k0 q) \) V4 M7 d. l2 g6 `
Key words:
* N# S6 ]6 L' {, e- TOUCH CURRENT for equipment
, |% ? F( {; c1 A t/ zwith multiple supplies6 ^7 E1 f" A5 M2 j' e8 W
Decision taken at the 41st/ ^' n( U( p3 \2 R
CTL meeting 2004. This4 b/ V3 p, t% m U. B% b: D+ B5 M
decision replaces n. 3943 a) \8 A/ w E
taken at the 39th CTL* a, u, [4 E0 G2 w$ B5 K( _, y
meeting 2002
* H/ j7 J$ k3 x5 sQuestion:
3 Z6 O5 Q6 V) J7 y" r8 [3 F1. Should the TOUCH CURRENT be measured for each individual supply source to determine if the% C; y7 Q6 `% A K* a" u
PROTECTIVE CONDUCTOR CURRENT exceeds 3.5 mA and if it does exceed, then require PERMANENT
/ Q7 f0 @7 ]! v% j' [* ~or PLUGGABLE TYPE B connection to the supply and meet 5.1.7?
! |. P, g5 R% y0 W7 n2. Should the cumulative TOUCH CURRENT be measured to determine if the total TOUCH CURRENT0 M/ c! R3 [2 M, k
exceeds 3.5 mA? If the total TOUCH CURRENT does exceed 3.5 mA then require that AC MAINS
# H2 ]* O7 z5 i# |9 ISUPPLY to be connected to separate AC MAINS SUPPLY circuits with at least one source having a" r! _5 s7 W8 R- L% J
reliable connection to PROTECTIVE EARTH (e.g. be PLUGGABLE TYPE B or PERMANENTLY" c+ f) }2 _2 M+ H
connected EUT?
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PLUGGABLE EQUIPMENT TYPE A does not have a reliable connection to building PROTECTIVE EARTH. Therefore, if
4 o8 U3 r+ Z. _the TOUCH CURRENT measurement exceeds 3.5 mA, then that particular source needs to be PERMANENTLY# V, c. ^) P* t7 @8 m9 U" a0 Z+ {* T+ q
connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. In older buildings, EARTH may: H5 M6 j* J) C, f, J) A
not be present on the PLUGGABLE TYPE A socket outlets on the wall. The multiple connection does not help, as all0 r1 N- A: h0 z# ?- M+ t% ^
such socket outlets may not have EARTH connection. Therefore, if the individual or cumulative PROTECTIVE, x5 V9 [4 M, \! q' ?# a( K3 t
CONDUCTOR CURRENT exceeds 3.5 mA, then at least one of the sources needs to be PERMANENTLY connected or+ }8 j0 v6 P: K1 k" D {5 g- I
have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. If one of the sources is required to be
! `* o+ A6 y1 n' }5 x4 a& e/ e; nPERMANENTLY connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH in order to
- W; M# S" v0 j* i: y% xcomply with the TOUCH CURRENT requirements, the equipment shall be provided with both a marking on the equipment
: N2 O* W5 w% R+ W1 Eand a statement in the installation instructions, specifying that the USER is to disconnect all power sources connection: ^/ l8 L' A) ^+ {" H7 h. E
before disconnecting the PERMANENT connection or the PLUGGABLE TYPE B connection
, S! y7 e' w% G& u) jDecision:
; F5 q; ^6 `, {See copy of the CDV for IEC 60950-1 2nd edition on Page 20 i9 K; w& Z# U- o: h0 h
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