The thickness of a cable, in AWG (smaller number = thicker) or mm². Thicker wire carries more current with less heat and less voltage loss; the design sizes each run to its load and length.
Too-thin wire overheats and drops voltage; too-thick wastes money. Sizing each run to its current and length is the single most important safety decision in a DC system.
Every conductor in the system has a gauge sized to the current it carries and the length it runs, so it stays cool and within a voltage-drop budget.
Design your van, boat, cabin or RV system in Wattonomy and it sizes every cable in AWG or mm² to carry its fuse and stay under a 3% voltage drop for your actual run lengths — from the appliances you actually run, sized to the recognized standard for your region. You see it on the wiring diagram, in the sized parts list, and in a plain-English build pack that explains the reasoning behind every choice. No account, no email — about a minute to a complete, validated design.
By the current the wire carries and how far it runs — higher current and longer runs need thicker wire. Wattonomy sizes each conductor to ampacity and voltage drop automatically.
They measure the same thing differently — AWG (smaller number = thicker) in North America, mm² elsewhere. Wattonomy shows whichever your region uses.
It takes about a minute. No account, no email.