====== Wiring the van ======




===== basic principles =====

  * wire
    * wire runs are typically sized for critical vs noncritical applications.  Factors include both the **amount of current** and the **total length of the circuit** (POS and NEG sides combined).  See below.
    * **stranded wire** is used in mobile applications;  solid wire is more susceptible to damage and loosening from vibration
  * solid-copper wiring is used in DC applications, like the van's 12vdc.  Copper-clad aluminum (CCA) is sometimes used in AC applications but is not appropriate for DC.((DC has no "skin effect" in wires, so the copper cladding is ineffective))
  * fuses
    *  **fuses exist to protect the wiring**.  
    * fuses are **sized 20% over the wire's rating**.  Example:  a wire that is rated for 40A would be fused at ≤48A.
    * fuses are placed **as close to the source of the power as practical** to protect the maximum amount of wire
    * fuses are typically placed on the POS leg

===== critical vs noncritical applications =====

Current on any wire tends to cause //voltage sag//.  The problem gets worse as current approaches the wire's rated capacity.  Some applications are greatly affected by sag and require heavier wiring.  Some applications are fine with some sag.

**Critical applications** require voltage sag of ≤3%.  With 3% sag 14.4v at the source drops to 13.97v at the other end of the wires.  Some critical applications might include:

  * solar charge controller output to battery bank
  * solar panel to solar charge controller
  * battery bank to fuse panel
  * power distribution runs from one side of the van to the other (bus to bus) 
  * DC-DC charging of the house bank from alternator
  * sensitive electronics
  * inverters running large loads

**Noncritical applications** can accept voltage sag of ≤10%.  With 10% sag 14.4v at the source drops to 13.0v at the other end of the wires.  Some noncritical applications might include:

  * isolator charging of the house bank ([[electrical:12v:alternator#example|details]]), especially when some solar is present
  * MaxxFan control boards are sensitive to overvoltage and may prefer some sag 


A [[http://assets.bluesea.com/files/resources/newsletter/images/DC_wire_selection_chartlg.jpg|well-respected chart showing critical and noncritical wiring selection]] is published by Blue Sea.