"Jim Wilkins" wrote in message
news

Clamp meters are intended to read the magnetic field around a single
conductor. If more than one wire passes through the clamp they
should show the difference between the currents, which is zero if
the same current passes through in opposite directions.


I should have written the algebraic sum of the currents, with the sign
depending on the direction of current flow.
http://hyperphysics.phy-astr.gsu.edu...ctric/gfi.html

-jsw