Are you actually trying to detect current in the cable or would voltage=
 be
OK?

The simplist way to detect AC  voltage is to wrap wire over the cable f=
or
about 100mm or so . This will have a capacitance to the live conductor =
as
well as the neutral & earth conductors. So a voltage divider is formed =
-
at quite high impedance. But a couple of diodes to clip the voltage and=
 a
connection to an input port are all that is required to detect if the
circuit is "live" or "dead". Isolation is provided by the cable sheath =
an
wire insulation so there is no worries here. You need an earth connecti=
on
to your detector however.

If you really need to detect current, then a simple magnetic detector i=
s
probably the easiset. e.g a single or 1/2 turn  though a core with seco=
ndry
of many turns & a load resistor. It does mean you have to split the cab=
le
however to separate the go & return paths.
Placing a rod type  magnetic core with 100+ turns (e.g a nail with wire=

wrapped around it !) next to the feed cable may work, depending on a nu=
mber
of factors, but may not be reliable either, it will depend on cable
construction, current level, length of core, number of turns... etc. I
haven't tryed this but have used the voltage detect version above.

Richard P





What is the smartest and lowest cost method to detect if there is a
current flowing in a 110/220 V cable, preferably without doing any thin=
g
else with the wire then to attach something outside of the cable.

/Ake

 ---
Ake Hedman (YAP - Yet Another Programmer)
eurosource, Brattbergav=E4gen 17, 820 50 LOS, Sweden
Phone: 46 657 413430 Cellular: 46 730 533146
Company home: http://www.eurosource.se      Kryddor/Te/Kaffe:
http://www.brattberg.com
Personal homepage: http://www.eurosource.se/akhe

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