Inverter Wiring Protection Todd Cory Inverter primary wiring has always been difficult for me to justify protecting. Due mainly to the high costs of UL approved safety interruption devices, and low probability of a short in the circuit. I recently researched the following fuse, with the help of my friend, Bill Munholand, at Mt. Shasta Electric. I now include this on all wiring jobs involving battery driven inverter systems that I do. Ordering Info Cross Reference Reliance/Brush #RFA Bussman #KAA Gould/Shawnut #A 13X The length of a 300 amp fuse is 2 5/8" x 1" wide. Follow the fuse catalog symbol with the desired amperage, for example a Trace 2012 would require a 300 amp fuse. So, if ordering a Buss fuse it would be a KAA-300. Available amperage ratings vary from 1 to 2,000 amps, UL approved for up to 130 VDC, with a DC interruption rating of 50,000 amps. The fuse, and Buss #3575 fuse block are rather inexpensive, considering the alternatives. A KAA-300 goes for around $35.00 with $20.00 for the connection/mounting block. The Acid Test The insertion loss is quite acceptable. Testing was done at a neighbor's house, with their Trace 2012, driven by 6 Trojan L-16s. I chose nice, heavy resistive loads for this, and turned on their 1000 watt iron and 900 watt toaster. I measured the voltage drop across their 3' of 1/0 copper inverter primary wire with the previously mentioned fuse installed in line. The voltage drop with some 150 amps flowing was a meager 121.3 mV as measured with my Fluke D 800 digital meter. Conclusion As the N.E.C. requires protection of all circuits, this fuse makes compliance with regulations and incorporation of safe wiring of remote/home power systems not only easy but, inexpensive too. Thanks to Bill Munholand for his help in tracking down this fuse and to Gary and Terri Orwig for the use of their system for testing procedures. Access Bill Munholand, Mt. Shasta Electric, 110 W Castle St., Mt. Shasta, CA 96067 ¥ 916-926-3842 Todd Cory, Bald Mountain Solar, POB 313, Big Bend, CA 96011 ¥ 916-337-6317