Regardless of what the books and theory tell you, 12 gauge is NOT sufficient for a sustained 20 amp load over an extended length of cable. Count on using 10 gauge for a 20 amp circuit. I have measured sizable voltage drops with the resultant loss of power output when trying to pull 30 amps through 8 gauge at a length of less than 25 feet. This was using a large RF amplifier as the current draw, but it would be no different than if it were a large audio amp with a sustained duration note ( pipe organs, dance music aka "electronica", etc...).
As to products being UL listed and working off of a 15 or 20 amp circuit, that is true. HOWEVER, that would be under "normal use" conditions. It is possible that large amps running at very low impedances with a low efficiency load can pull more than 15 or 20 amps.
As a case in point, the "standard" Sunfire two channel amp rated for 300 @ 8, 600 @ 4, etc... WILL blow a 15 amp breaker if you are throttling it. If you supply a "real" 20 amps of current to this amplifier, it is capable of producing almost 1500 wpc RMS ( NOT "peak" ) @ 2 ohms. I have an actual review where they ran into this problem. Not only did the amp blow the factory supplied 10 amp fuses installed, they had to up the supply to 20 amps to drive the amp into clipping at 2 ohms. Once they did that, it was able to SUSTAIN a whopping 1450+ wpc.
Now if you compound that type of power draw by adding multiple channels to a high powered HT amp ( like the 200 / 400 wpc X 5 channel Sunfire Cinema Grand or the 400 / 800 wpc x 5 channel Sunfire Cinema Grand Signature ) and / or simply go to a larger 2 channel amp ( 600 / 1200 wpc Sunfire Signature ) or an amp that is both high powered and in-efficient ( Krell, Perreaux, Threshold's, etc... ), you can see where this is going. One might never get into such a situation unless they have low impdedance / low sensitivity speakers and / or like to listen at very loud levels.
In my specific case, some of my systems fall into ALL of those "bad" / "tough to deal with" categories. As such, i found out about this the hard way. About two months ago, i had an amp that was going into thermal shutdown due to current starvation. I sent it back to the factory for an inspection and everything checked out fine. It is at this time that they brought up the amount of current necessary to sustain the levels that i was running at. This forced me to do some checking on my end. Needless to say, I had to change how i had some things set up on my end to correct the situation. The good thing about this is that while they had the amp, they performed some newer upgrades / heavy duty modifications to the amp at no charge and even covered the return shipping. Sean
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As to products being UL listed and working off of a 15 or 20 amp circuit, that is true. HOWEVER, that would be under "normal use" conditions. It is possible that large amps running at very low impedances with a low efficiency load can pull more than 15 or 20 amps.
As a case in point, the "standard" Sunfire two channel amp rated for 300 @ 8, 600 @ 4, etc... WILL blow a 15 amp breaker if you are throttling it. If you supply a "real" 20 amps of current to this amplifier, it is capable of producing almost 1500 wpc RMS ( NOT "peak" ) @ 2 ohms. I have an actual review where they ran into this problem. Not only did the amp blow the factory supplied 10 amp fuses installed, they had to up the supply to 20 amps to drive the amp into clipping at 2 ohms. Once they did that, it was able to SUSTAIN a whopping 1450+ wpc.
Now if you compound that type of power draw by adding multiple channels to a high powered HT amp ( like the 200 / 400 wpc X 5 channel Sunfire Cinema Grand or the 400 / 800 wpc x 5 channel Sunfire Cinema Grand Signature ) and / or simply go to a larger 2 channel amp ( 600 / 1200 wpc Sunfire Signature ) or an amp that is both high powered and in-efficient ( Krell, Perreaux, Threshold's, etc... ), you can see where this is going. One might never get into such a situation unless they have low impdedance / low sensitivity speakers and / or like to listen at very loud levels.
In my specific case, some of my systems fall into ALL of those "bad" / "tough to deal with" categories. As such, i found out about this the hard way. About two months ago, i had an amp that was going into thermal shutdown due to current starvation. I sent it back to the factory for an inspection and everything checked out fine. It is at this time that they brought up the amount of current necessary to sustain the levels that i was running at. This forced me to do some checking on my end. Needless to say, I had to change how i had some things set up on my end to correct the situation. The good thing about this is that while they had the amp, they performed some newer upgrades / heavy duty modifications to the amp at no charge and even covered the return shipping. Sean
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