See the following blogs for tests that demonstrates High-Side Current Shunt measurement:
or
http://www.element14.com/community/...ns3-current-shunt-test-big-errors-are-posible
- High common mode voltage.
- Big error (100 x) using 2-wire connection
- Why you should use 4-wire connection whenever possible.
- The advantages of isolation amplifiers.
or
http://www.element14.com/community/...ns3-current-shunt-test-big-errors-are-posible