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<blockquote data-quote="McIntosh" data-source="post: 6090392" data-attributes="member: 605496"><p>The National electrical code determines ampacity, not some car audio &quot;specialty&quot; manufacturer. Monster, nor any other can produce &quot;special&quot; copper capable of more ampacity. The weak link is the insulation. Underhood temperatures far exceed the code&#039;s basic limits. 90 degrees C is only 194F. There are correction factors for higher temperatures. 1/0 is good for 170 amps at 86F ambient. At 71C (about 160F) multiply that ampacity by .41. That drops it to 170X.41=69.7 amps. Yes there is some conservatism in the code. Wires can get quite warm when the code is followed. Warm as opposed to hot. You&#039;re probably not drawing anywhere near as much current as you think you are. Manufacturers lie nowadays. That wimpy switching power supply has no nads. False power claims abound. 746Watts=1HP. Do the math on your ShopVac and I&#039;m sure you&#039;ll see a 15 amp breaker couldn&#039;t possibly hold. 746/120=6.22 amps/HP. This means the max HP for a 15A circuit is 2.41HP. 5+HP shop vacs abound. They lie.</p></blockquote><p></p>

[QUOTE="McIntosh, post: 6090392, member: 605496"] The National electrical code determines ampacity, not some car audio "specialty" manufacturer. Monster, nor any other can produce "special" copper capable of more ampacity. The weak link is the insulation. Underhood temperatures far exceed the code's basic limits. 90 degrees C is only 194F. There are correction factors for higher temperatures. 1/0 is good for 170 amps at 86F ambient. At 71C (about 160F) multiply that ampacity by .41. That drops it to 170X.41=69.7 amps. Yes there is some conservatism in the code. Wires can get quite warm when the code is followed. Warm as opposed to hot. You're probably not drawing anywhere near as much current as you think you are. Manufacturers lie nowadays. That wimpy switching power supply has no nads. False power claims abound. 746Watts=1HP. Do the math on your ShopVac and I'm sure you'll see a 15 amp breaker couldn't possibly hold. 746/120=6.22 amps/HP. This means the max HP for a 15A circuit is 2.41HP. 5+HP shop vacs abound. They lie. [/QUOTE]

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