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What fusing is correct here?
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<blockquote data-quote="Hcw" data-source="post: 7526593" data-attributes="member: 637045"><p>To determine the approximate current draw in “amps” of one’s amplifiers you need to calculate the total power of each amp. Multiply total number of channels times the number of RMS watts per channel. In this particular example we will use the first amp at 4x 150 rms watts = 600w rms. The second amp 1x 280w rms = 280w rms. These total 880w rms. This total is than doubled and divided by 13.8 to give approximate “current draw. So our total 880w rms x 2 = 1760 divided by 13.8 = 127 amps.</p><p></p><p>Using this figure of 127 amps we can determine the proper wire gauge size from charts. In this case we need to run a length of wire 10-13 ft. According to the charts on the net <a href="http://www.crutchfield.com/Learn/learningcenter/car/cable_gauge_chart.html" target="_blank">Cable Gauge Chart</a> this would require a 4 gauge power wire to be run between the battery and the amps capable of supporting up to a maximum of 150 amps.</p><p></p><p>Questions:</p><p></p><p>So from this information does it mean that the power lead should be fused with a 150 amp fuse at the battery?</p><p></p><p>This would include that this lead is going to a junction block and each power lead from the junction block going directly into each amp?</p><p></p><p>I ask this as there are articles stating that one should add the sum of all fuses in the amps which in my case as an example would be 2x70amps in the first amp = 140 amps for it. The second amp has a 40 amp fuse for a combined total of 180amps.</p><p></p><p>Question:</p><p></p><p>So what than doe’s one fuse for at the battery? The maximum amount the 4 gauge wire is capable of supporting which is 150 amps or this new Figure of 180 amps? (30 amp difference) or the figure we obtained at the top of this page for “approximate amp draw” that was figured at 127 amps?</p><p></p><p>To further confuse issues we are told that the amps are protected with their built in fuses and that we are only protecting the “power wire” lead between TWO POINTS in case of shorts. This brings up the question of fusing between the battery and a junction block and than running from the junction block directly into each amp. Unless these power leads of the same 4 gauge are fused at this point between each amp and the junction block they are relying on the fuse at the battery as well are they not?</p><p></p><p>So adding a fuse between the junction block and each amp would protect these leads in the event of them shorting? These would have 140 amps on the first amp and a 40 amp on the second amp to match to their fuse rating built in?</p><p></p><p>So the question is by adding these additional fuses between each amp and the junction block does it make any difference in the fuse size that one uses at the battery because they are individually fused as well? This pertaining to the three different amperage Numbers we have obtained:</p><p></p><p>-The approximate current draw of 127 amps at the start of all this.</p><p></p><p>-The 125-150 amp figure the 4 gauge wire is capable of carrying (between battery and Junction Block)</p><p></p><p>-The 180 amp figure the total sum of all built in fuses to the two amps?</p><p></p><p>In another artical it states that you can fuse this power lead at the battery with a 60-80 amp fuse on a 4 gauge it is all it will need???</p></blockquote><p></p>
[QUOTE="Hcw, post: 7526593, member: 637045"] To determine the approximate current draw in “amps” of one’s amplifiers you need to calculate the total power of each amp. Multiply total number of channels times the number of RMS watts per channel. In this particular example we will use the first amp at 4x 150 rms watts = 600w rms. The second amp 1x 280w rms = 280w rms. These total 880w rms. This total is than doubled and divided by 13.8 to give approximate “current draw. So our total 880w rms x 2 = 1760 divided by 13.8 = 127 amps. Using this figure of 127 amps we can determine the proper wire gauge size from charts. In this case we need to run a length of wire 10-13 ft. According to the charts on the net [URL="http://www.crutchfield.com/Learn/learningcenter/car/cable_gauge_chart.html"]Cable Gauge Chart[/URL] this would require a 4 gauge power wire to be run between the battery and the amps capable of supporting up to a maximum of 150 amps. Questions: So from this information does it mean that the power lead should be fused with a 150 amp fuse at the battery? This would include that this lead is going to a junction block and each power lead from the junction block going directly into each amp? I ask this as there are articles stating that one should add the sum of all fuses in the amps which in my case as an example would be 2x70amps in the first amp = 140 amps for it. The second amp has a 40 amp fuse for a combined total of 180amps. Question: So what than doe’s one fuse for at the battery? The maximum amount the 4 gauge wire is capable of supporting which is 150 amps or this new Figure of 180 amps? (30 amp difference) or the figure we obtained at the top of this page for “approximate amp draw” that was figured at 127 amps? To further confuse issues we are told that the amps are protected with their built in fuses and that we are only protecting the “power wire” lead between TWO POINTS in case of shorts. This brings up the question of fusing between the battery and a junction block and than running from the junction block directly into each amp. Unless these power leads of the same 4 gauge are fused at this point between each amp and the junction block they are relying on the fuse at the battery as well are they not? So adding a fuse between the junction block and each amp would protect these leads in the event of them shorting? These would have 140 amps on the first amp and a 40 amp on the second amp to match to their fuse rating built in? So the question is by adding these additional fuses between each amp and the junction block does it make any difference in the fuse size that one uses at the battery because they are individually fused as well? This pertaining to the three different amperage Numbers we have obtained: -The approximate current draw of 127 amps at the start of all this. -The 125-150 amp figure the 4 gauge wire is capable of carrying (between battery and Junction Block) -The 180 amp figure the total sum of all built in fuses to the two amps? In another artical it states that you can fuse this power lead at the battery with a 60-80 amp fuse on a 4 gauge it is all it will need??? [/QUOTE]
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