In some ways batteries are safer than conventional AC power. It’s fairly difficult to shock yourself at low voltage. But in other ways batteries are more dangerous: They can supply many more amps into a short circuit, and once a DC arc is struck, it has little tendency to self-snuff. One of the very sensible things the National Electrical Code requires is fusing and a safety disconnect for any appliance connected to a battery bank. Fusing is extremely important for any circuit connected to a battery! Without fusing you are risking burning your house down.

There are several products readily available to cover DC fusing and disconnect needs for inverter-based systems. For full-size inverter fusing, depending on system requirements you can either use a properly sized Powercenter, or the very popular Trace DC Disconnect. Our technical staff can answer your questions about which one is better for you. Mid-sized inverters can use a Class T fuse with a Blue Seas circuit breaker to pro vide safe and compliant connection. All this safety and connection equipment is covered in the Safety section of this chapter. Generally, you’ll need a 200- to 400-amp fuse for full-size inverters, a 100- to 200-amp fuse for mid-size inverters, and small inverters will be plugged into a 20- or 30-amp fused outlet.

The size of the cables providing power to the inverter is as important as the fusing, as we noted earlier. Do not restrict the inverter’s ability to meet surge loads by choking it down with undersize or lengthy cables. Ten feet is the longest practical run between the battery and inverter. This is true even for small 100- to 200-watt inverters. Put the extension cord on the AC side of the inverter! You’ll find cable and circuit breaker requirement charts with the larger inverters. Batteries should either be the sealed type, or live in their own enclosure. Don’t put your inverter in with the batteries!