UNI-T UT211B Clamp Meter

Capable of non-incircuit measurement of both AC & DC, that's current not voltage. Also comes with a set of conventional probes; Voltage, Current (DC & AC RMS), Frequency, Resistance, Impedance, Diode, Capacitance.

Supports electric field detection where it beeps faster and faster (like a 70's movie bomb detector).

Complete with plastic carry pouch & badly translated "engrish" instructions.

Ebay £50 inc delivery from China.

You pass a wire through the "claw" and it will measure the current flowing from the field. However, this won't work if there are two wires in opposite directions, eg live and neutral, since the field will cancel. If you want to measure separate flows, for example Earth leakage, you could rig up something like this:

Picture courtesy of Mingozzi.