All of the electrical equipment on your boat is de3signed to operate within certain engineered voltage levels. Electronic equipment in particular is quite fussy about this matter. To that end, the ABYC describes two levels of acceptable voltage drop for on board electrical circuitry. Maximum levels of drop at 3% and 10% are identified. The specific circuits that 3% is allowed at are navigation lights, bilge blower circuits, panel board main feeder cables and mission critical electronic circuits. Its important to note that the standard actually states "electronics". The intent of this is really mission critical as we have since defined. Truth is, if your DC powered AM/FM stereo/CD/IPOD/MP3 player has a bit of excessive voltage drop in its power supply, nobody really cares, and its not going to me life threatening. Your GPS or VHF radio on the other hand, could be a different story. You get the idea.