Second Circuit - Brooklyn, USA - and a couple of other places are in it too, like New York State, Connecticut and Vermont. Go Second Circuit Court of Appeals!
No, the circuit should not be energized when checking the resistance of a circuit.
short circuit
Use a multimeter and test if there is a voltage drop or current over the wire circuit.
Active, hot, on, or live.
There is a circuit live somewhere.
The live wire
A safety obeserver who has a wooden object to pull you from the live circuit. They must be trained in CPR and know where the circuit breakers are to deactivate the dangerous circuit in case of a mishap.
Not touching a live conductive part of a circuit is a great way to prevent you from receiving an electrical shock! Along with this the circuit breaker should trip if there is a fault on the circuit, or a GFCI if there is no ground in the circuit
This is a short circuit which will create sparks. The breaker or fuse on the circuit will likely trip or blow.
ammeter
What is the question? Assuming you're talking about short circuiting the live circuit, as soon as a phase to ground fault occurs protection will operate, opening a circuit breaker.
No. An RCD operates by detecting fault currents on the circuit protective conductors(earth). An MCB(mini trip) should operate with a live to neutral fault(over-heating the circuit).