DSH 394A Touch current for equipment having multiple supplies supplying power

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DSH 394A 5 Y2 Z: |: L, q% v 9 r* Q, j& r/ ?7 R$ W1 K9 s

Touch current for equipment having multiple supplies supplying power simultaneously * Y/ A+ V" I; v0 L" a) c4 O

5.1.2, last paragraph / 5.1

60950-1(ed.1) & 60950(ed.3)   v& m. u8 F9 p  ]) G9 C

; W2 g1 a+ ]! r4 t& K1 y) v! YStandard(s):
IEC 60950 (1999) 3rd Ed.
IEC 60950-1 (2001) 1st ed.
. X/ ^$ y" I2 g( _Sub clause(s):
* n! D/ t2 h) ]4 L0 x, m5.1.2, last paragraph
! A1 i1 w; K& J8 d1 _( o- `5.1
+ y4 X! l: e( J" ?Sheet n°: 394A
6 p/ b6 x  L" T" [! w- G' t0 ]Subject:
TOUCH CURRENT for equipment
. ]- U& F" q2 F* chaving multiple supplies supplying
power simultaneously
$ v* P# f. i, g( b; @  @Key words:
- TOUCH CURRENT for equipment
with multiple supplies
Decision taken at the 41st
CTL meeting 2004. This
decision replaces n. 394
taken at the 39th CTL
meeting 2002
Question:
9 g; p! T8 e5 Q9 M1. Should the TOUCH CURRENT be measured for each individual supply source to determine if the
PROTECTIVE CONDUCTOR CURRENT exceeds 3.5 mA and if it does exceed, then require PERMANENT
or PLUGGABLE TYPE B connection to the supply and meet 5.1.7?
) [  C3 K) f/ I: F2. Should the cumulative TOUCH CURRENT be measured to determine if the total TOUCH CURRENT
& P( o5 b+ C, r3 K* gexceeds 3.5 mA? If the total TOUCH CURRENT does exceed 3.5 mA then require that AC MAINS
SUPPLY to be connected to separate AC MAINS SUPPLY circuits with at least one source having a
5 a: a9 w! d& F( E, ~reliable connection to PROTECTIVE EARTH (e.g. be PLUGGABLE TYPE B or PERMANENTLY
* r1 ~8 `+ P! H6 J" ^; u% vconnected EUT?
Rationale:
2 }5 o% x: B& n9 Z3 t  rPLUGGABLE EQUIPMENT TYPE A does not have a reliable connection to building PROTECTIVE EARTH. Therefore, if
+ G  g" J; H5 K2 j; a; Sthe TOUCH CURRENT measurement exceeds 3.5 mA, then that particular source needs to be PERMANENTLY
+ O1 }; i6 l1 r4 Zconnected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. In older buildings, EARTH may
" d4 {3 n2 x6 @+ xnot be present on the PLUGGABLE TYPE A socket outlets on the wall. The multiple connection does not help, as all
such socket outlets may not have EARTH connection. Therefore, if the individual or cumulative PROTECTIVE
; g; _1 v& I" o, m; |% {CONDUCTOR CURRENT exceeds 3.5 mA, then at least one of the sources needs to be PERMANENTLY connected or
have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. If one of the sources is required to be
9 w0 i% Z4 R% ]7 dPERMANENTLY connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH in order to
0 A* y$ t2 _$ o# |comply with the TOUCH CURRENT requirements, the equipment shall be provided with both a marking on the equipment
: {$ m- K+ U/ T: v* [4 V( band a statement in the installation instructions, specifying that the USER is to disconnect all power sources connection
  ?% X6 U& ~% ~0 o! h. Fbefore disconnecting the PERMANENT connection or the PLUGGABLE TYPE B connection
; q2 I* V0 P- |: h$ [5 j5 S6 qDecision:
See copy of the CDV for IEC 60950-1 2nd edition on Page 2

6 D2 m1 ~4 G7 A9 H. [
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