One of the golden rules of automotive electrical system design is that every circuit in the electrical system has a protection device. This means that an accidental problem or failure – such as the wiring being grounded, shorted, or overloaded does not lead to damage (or worse). This basic wiring system protection is accomplished in several ways.
NOTE: If you’re using a Hot Rod Wires® universal wiring harness you do not have to be concerned about adding protection to your harness. All of our harnesses are built with basic protection. However, if you’re creating your own wiring system from the ground up – or if you’re using a harness that lacks basic protection – this is very important information.
The main protections every harness should have:
- The main power supply line from the battery to the rest of the system needs to be protected with either a) the correct gauge fusible link or b) a correctly sized max fuse.
- Each individual circuit within the wiring harness should be protected with the correct size fuse or circuit breaker. For example, the correct size tail and park lamp fuse would protect these circuits if a problem occurred.
- Every circuit must have wire that’s properly sized for the potential electrical load. If, for example, you install halogen headlights in your vehicle but you use a headlight circuit with wiring that’s too small, you’ll have problems with heat and voltage loss (at a minimum). Serious damage is always possible in this scenario.
- The system – and the vehicle frame – must be properly grounded. If your vehicle is older and/or improperly grounded, you can have all sorts of problems with various systems (from ignition to the stereo). A ground kit is a good idea if you suspect inconsistent grounding.
NOTE: Seal beam headlight circuits are protected with a circuit breaker built into the headlight switch. Thus, these circuits can rely on the headlight switch if a problem occurred.