To expand on Eric Henning's comment on voltage definition, EN 60204 (similar
to IEC 204), has yet a different definition for PELV:
"6.4 Protection by the use of PELV (Protective Extra Low Voltage)
This measure is intended to protect persons against electric shock from
direct contact and indirect contact (see IEC 364-4-41).
PELV circuits shall satisfy all of the following conditions:
a) limitation of maximum nominal voltage to 25 V a.c. or 60 V d.c.;
b) limitation of maximum current (in case of failure) to 1 A a.c. or 0.2 A
d.c.;
c) limitation to 80 mm2 of any area not protected against direct contact;
d) usage only indoors with dry conditions;
e) the source of supply and live parts of such circuits shall be separated or
isolated from circuits with higher voltages according to 6.3.3 and 15.1.3;
f) one side of the circuit or one point of the source of the supply of that
circuit shall be connected to the protective bonding circuit associated with
the higher voltages;
g) exposed conductive parts associated with such circuits shall be either
separated or isolated from higher voltage circuits in accordance with 6.3.3
or connected to the protective bonding circuit associated with the higher
voltages;
h) plugs and socket-outlets shall comply with the following:
1) plugs shall not be able to enter socket-outlets not in accordance
with
this subclause; and
2) socket-outlets shall exclude plugs of circuits not in accordance with
this subclause;
i) where such circuits are used as control circuits, they shall also fulfil
the relevant requirements of clause 9."
So, I certainly agree that not all ELVs are equal.
