Ananda Power Tech's Inverter Safety Switch tested by Richard Perez, Karen Perez, and Sam Coleman copyright 1992 Home Power Magazine THE BIG SWITCH. Everyone familiar with electricity knows about the BIG SWITCH. The Big Switch is what you pull when things don't go right, when electrical heaven and hell crashes in ruin about your feet. Ananda's 400 Ampere fused safety switch protects inverters, batteries, homes, and humans from catastrophic electrical failures. So why a Big Switch? When you have a battery you have a tiger by the tail. Even a small battery of a few hundred Ampere-hours can deliver thousands of Amperes of short circuit current for several seconds. Short circuits in the high current, low voltage wiring surrounding batteries and inverters can cause fires and even explosions. The main areas needing protection are the battery cabling and the cables from the battery which feed the inverter. These circuits can routinely transfer more than 300 Amperes of current. The National Electric Code requires, and common sense agrees, that these high current lines should have a fused disconnect. The Ananda Big Switch is up to this job. About this Big Switch Ananda Power Technologies designed this switch with inverters, operated from low voltage batteries, in mind. This switch will handle 2,000 Amperes of current. The model I tested (SF 400 T) is equipped with a 400 Ampere, DC Rated, Class T, current-limiting fuse. The Ananda Big Switch measures 7.5 inches wide by 7 inches tall (including switch lever) by 4 inches deep. It is very solidly made and you should give it to your kids when you're done with it. The Big Switch is fitted with 250 MCM lugs which easily accepted the massive 0000 copper cable we used. The switch is activated from above by pulling a lever. The switch is enclosed in a plastic housing to prevent accidental electrical contacts. The Big Switch Test We installed the Big Switch in line between a large inverter and a 600 Ampere-hour, 12 Volt nicad battery pack (60 Nife HIP-10 cells in series/parallel). We used the 0000 copper welding cables, also made by Ananda, as interconnects. These five foot cables have massive soldered ring connectors. We inserted a 500 Ampere, 50 milliVolt, shunt in line to measure DC current flowing thorough the Big Switch. We loaded the inverter and measured both the current flowing through the switch, and the battery voltage. Simultaneously we also measured the voltage loss across the entire switch, fuse, and two associated 250 MCM connector assembly. Fluke 87 DMMs were used as measuring instruments. Test Results The figure below shows the data we collected from operating the Big Switch and some interesting data we derived from our measurements. The bottom line is that we ran over 3,800 Watts of power (330 Amperes at 11.58 Volts DC) through this switch and it was 99.39% efficient (70.3 mV. loss across the entire assembly). The performance of the Ananda Big Switch is outstanding! The entire assembly, including the actual switch, the fuse, and all the connections, had an median resistance of 0.0002057 Ohms during our entire test. The entire Ananda Big Switch assembly has less electrical resistance than four feet of 0000 gauge copper welding cable! In the past I have not been interested in most "protection" devices marketed to home power folks. These devices were too cheaply made and had too much loss in high current DC circuits. The Ananda Big Switch has changed my mind. With an efficiency of 99.39% at 330 Amperes, we can have the safety of a fuse and a disconnect switch anywhere we need it without losing appreciable power in the protection device. Conclusions We at Home Power probably take home less pay that most of the folks who read this magazine. For us to plonk down $325 of our very hard earned bucks for this Big Switch, you must know that it works and is worth what it costs. I know this is a lot of money, but then the folks at Ananda make less than either you or me. We priced out a similar fused disconnect from an electrical supply house and the wholesale price was over $600 (retail was $1,480). When it comes to over current protection and switching high current, the Ananda SF 400 T is the best device I have ever seen, tested, or even heard about. I sleep easier knowing it's on the wall of our power room. Access Authors: Richard & Karen Perez, and Sam Coleman, c/o Home Power, POB 130, Hornbrook, CA 96044 ¥ 916-475-3179 Makers: Ananda Power Technologies, Inc., 14618 Tyler Foote Rd., Nevada City, CA 95959 ¥ 916-292-3834.