For fire and safety purposes, the National Electrical Code (NEC) has developed specifications for using low voltage DC circuits (<60Vdc) for powering indoor devices. Class 2 circuits are limited to 100 Watts of power per circuit, do not require the cables to be housed in conduit and can be installed by DAS technicians rather than licensed electricians. To ensure compliance with the 100W limitation, the power distribution equipment employs active current limiting circuitry.

Class 2 versus Class 3:
Class 2 considers safety from a fire initiation standpoint and provides acceptable protection from electric shock.
Class 3 considers safety only from a fire initiation standpoint. The output voltage can reach values up to 100Vdc on a 100VA power level.