DC Theory, Third Edition (NJATC) is a foundational electrical training textbook that covers the principles of direct current circuits for apprentices and journeyman electricians. It explains voltage, current, resistance, Ohm’s law, series and parallel circuits, power, energy, and basic troubleshooting, with clear examples and practice problems geared to IBEW–NECA training programs. This copy is brand new, with a crisp cover, tight binding, and perfectly clean pages, and it remains unused and ready for classroom work, exam prep, or as a clean reference copy in the shop or at home.