Regardless of how large or small a battery bank may be or what it's called upon to do, two wiring rules must be followed. First, all wiring should be installed in accordance with ABYC or, where mandated, CFR guidelines to ensure safety. Among the most important of these is the overcurrent protection mandate, which calls for a fuse or circuit breaker in every wire, save one, that leaves any battery's positive post. This overcurrent protection, often abbreviated as OCP, must be installed within 7" of the battery terminal. This distance may be increased to 72" if the wire is "sheathed." Sheathing can include anything from proprietary wiring loom to conduit; a wiring loom should meet ABYC guidelines for the protection it affords the wire as well as for fire resistance. Therefore, if you can follow any wire from any battery positive terminal for more than 7 " (or 72 " with sheathing) without bumping into a fuse or circuit breaker, the installation does not meet this important guideline, and the oversight should be corrected without delay. Any wire between the OCP and the battery is essentially unprotected and is therefore a fire risk in the event of a short circuit.
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