Most HO, N & Z Scale model locomotive motors and lamps are designed by the locomotive manufacturers to operate at full speed at 12 volts DC on the track.
Digitrax recommends running your DCC command station and boosters at the lowest track voltage possible that provides acceptable operation.
The “N Scale (12V)” setting on Digitrax equipment works for most HO, N & Z scale layouts.
Some DCC systems made by other companies supply more voltage to the track and are not adjustable.
If the track voltage applied exceeds the operating parameters of the locomotive and its lamps, it is possible for overheating to damage your locomotive whether you use DC or DCC.
For example, running an N Scale locomotive that was designed to run on 12-14 volts on a system that supplies 12 or more volts to the track may cause overheating and damage to the locomotive, its shell and your decoder.
Likewise, although not a decoder installation issue, using conventional incandescent light bulbs inside passenger cars may also result in heat distortion of the car shell.
Many manufacturers now offer "DCC Car Lighting" systems which use cooler LED's.