What is the typical current (in mA) carried by the 24v thermostat HVAC wire bundle in a typical low voltage application? I'm using 18/7 wire.
HVAC transformers are commonly rated 24 volts, 40 volt-amperes (VA). So they should be capable of providing about 1.6 amperes.
40 VA ÷ 24 V = 1.666666 A
However, the amount of current flowing, depends on what load is connected. If the load is only drawing 5 mA, then only 5 mA will flow on the wire.