Optimistic Paranoid
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- Jan 12, 2013
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<p>There are a number of threads here that talk about choosing inverters, and most, if not all of them, mention the necessity of putting a fuse in the wire between the battery and the inverter.</p><p>I haven't seen any discussion of the TYPE of fuse, or the fact that not all fuses are equal.</p><p>I have a copy of the Blue Sea Catalog (electrical components) and they have several pages devoted to fuses of many types:</p><p>MAXI Fuses range from 30 to 80 amps and have an interupt capacity of 1,000 amps.</p><p>MIDI or AMI fuses range from 30 to 200 amps and have an interupt capacity of 5,000 amps.</p><p>MEGA or AMG fuses range from 100 to 300 amps and have an interupt capacity of 2,000 amps.</p><p>ANL fuses range from 35 to 750 amps and have an interupt capacity of 6,000 amps. The Blue Sea catalog says that these</p><p>"meet the ABYC requirements for main dc circuit protection on large battery banks."</p><p>Class T fuses range from 225 to 400 amps and have an interupt capacity of 20,000 amps. The Blue Sea catalog says that these</p><p>"Have an extremely fast short circuit response." and are <strong><span style="text-decoration: underline;">"RECOMENDED BY MOST INVERTER MANUFACTURERS." </span></strong></p><p>Wikipedia says the following about interupting capacity:</p><p><em>"Breaking capacity or interrupting capacity is the current that </em><em>a fuse, circuit breaker, or other electrical apparatus is able to interrupt without being destroyed or causing an electric arc </em><em>with unacceptable duration. The prospective short circuit current which can occur under short circuit conditions should not exceed the rated breaking capacity of the apparatus. Otherwise breaking of the current cannot be guaranteed."</em></p><p>We know that under certain conditions of voltage and amperage, electricty can flow across an air gap. Spark plugs are an obvious example, and arc welders depend on this fact to melt steel and weld metals.</p><p>It looks to me like if a powerful inverter fails due to a short circuit, and you have it fused with the wrong kind of fuse, the fuse may blow, but the current may arc across the blown fuse and continue to flow, causing a fire which will probably destroy your vehicle.</p>