Answer to Question 1
Whenever possible, attach the test leads to the conductors with the circuit de-energized. This can be done with alligator clip type test leads. Always connect the neutral test lead first and then the hot test lead last. The circuit may then be energized for the reading to be taken. Once the reading has been obtained the circuit may once again be de-energized and the test leads removed by disconnecting the hot lead first and the grounded lead last.
Answer to Question 2
Two wires for control power and two wires for communication.
Covance primate-testing lab, Vienna, Virginia, 2004–05
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