12 Volt DC Electrical Circuit Protection

A Properly sized DC fuse or circuit breaker is a must when installing power inverters! No fuse or to large of fuse could result in fire or battery explosion if a short circuit was to occur.

As current passes through the inverter cable, heat is generated. If the inverter draws more current than the cable can handle due to heavy loads, excessive heat is produced. The fuse can handle a certain amount of excess current but is designed to blow when the safe limits are exceeded, protecting the cable and battery from melt-down or fire damage. A properly sized ANL, Class T fuse, or DC circuit breaker is worth every penny for the piece of mind you receive knowing that your 12 DC electrical circuits are protected.

Class T Fuses are our highest priced fusing option. Large Inverters require a Class T type JNN fuse. Xantrex specifically recommends a Class T fuse with their larger inverters. Class T fuses have a high arc interrupt rating and are specially designed to break and smother a direct current arc when the fuse blows. These small space saving fuses are UL listed and generally available in 300 and 400 amp ratings. Class T fuses can be mounted directly to the battery or they can be installed with an optional fuse holder and optional cover.
Class T fuse data sheet.

ANL Fuses are a cost effective 12 volt DC fusing option. ANL fuses are a non time delay current limiting fuse. The time limiting feature allows the ANL fuse to pass thru short periods of "over current" such as starting an induction appliance or motor. If the inverter manufacturer does not specify which type of DC fuse to install with their inverter an ANL fuse is a good option. ANL fuses are UL recognized and are available in 50 to 500 amp ratings. Unlike Class T fuses ANL fuses require a fuse holder.
ANL Fuse data sheet.

For small 1000 to 1200 watt or smaller power inverters a circuit breaker could be used to protect 12 volt DC circuits instead of using a Class T or ANL fuse.
Like fuses, DC circuit breakers need to be installed as close to the battery as possible. Although a bit pricey, circuit breakers do offer a viable option because they will provide the same short circuit or over load protection as a fuse.

We prefer the Bussmann CB185 Type III High Amp Waterproof circuit breaker. The CB185 is a manual reset circuit breaker that can also act as a power shut-off switch if manually tripped. It is available in 25 amp thru 150 amps.
CB185 Circuit Breaker data sheet.

All DC fuses or circuit breakers should be installed as close to the battery as possible. Preferably six inches or less.