Re-wired to 30 amps?

Mitch, check your local codes. Typical residential circuits are 15 and 20-amp for general power and lighting. Almost everywhere I know of you are not permitted to have more than one receptacle on a circuit rated greater than 20-amps. Not only that, a 30-amp branch circuit requires a 30-amp receptacle. Your conventional power cord plugs rated at 15 and 20 amp will not fit in a 30-amp receptacle.

No matter how power hungry your equipment is, they are all UL listed. This means that they are safe to operate in conventional 15 and 20-amp straight blade receptacles. And safety entails operation at peak performance.

Remember, the rating of a circuit is to protect it from overheating to the point of creating a fire hazard. Increasing wire size for a given current draw only reduces the voltage drop along the path. By going from a 20-amp #12 wire to a 30-amp #10 wire, the voltage drop only decreases by 0.024-volts per foot. Even if you have a 100-foot run, thats a 2.5-volt drop to the outlet; something a well designed power supply can handle with no problem. All day long.

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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It is a very good idea to go to a 30amp circuit. You will notice a big improvement. If you do go to a 30amp breaker, you must use 10awg wire! Either that or you better get more fire insurance. I have installed 10awg on a 20amp breaker and was tripping the breaker all the time. I went to a 30amp breaker and never had any trouble since. Now I use three dedicated 30amp 10awg circuits and love it. A friend of mine installed 8awg wire and said it was an improvement over his 10awg wire. But use atleast 10awg. John

Speakerdude, I disagree; probably many insurance adjusters will also. It is not a good idea to run a 30-amp circuit regardless of any potential sonic improvements. It goes against electrical codes and for good reason. The limiting factor here is the rating of the receptacle - the 20A straight-blades (both slots up/down) cannot safely handle more than 20-amps continuous. If a fault occurs in the outlet box and the circuit starts drawing a continuous 27 or 28 amps, say, the required 20-A circuit breaker will clear the fault by tripping. An electrician can then determine what happened. If you have the 30-A breaker, it will happily let the excess current through and the mounting strap on the 20-A outlet, the plug and cord will heat up and possibly fail. This is a fire in the making.

The purpose of a circuit breaker is to protect the wire, period. It will not protect the outlet or your equipment. If all of your equipment draw more than 16-amps combined, then they need to be on multiple circuits because you will keep tripping the breaker. If one piece of equipment draws more than 20-amps, then something's wrong because the plug, cord and the transformer primary fuses are rated for a 20-amp (max) circuit. Hence the UL rating.

So if you go for #10 or #8 wiring (or even 500MCM for that matter) there might be benefits based upon your situation. However, your equipment will still draw only what's needed regardless of how much extra fat you have on the wires. But the circuit breaker has to prevent excess current from shooting through via faults or shorts. It's a safety thing, that's all.

No one has even mentioned line surge impedance. The lower the better, let me repeat that: The lower the better.
Theories aside - always use at least 10awg wiring - your ears will thank you.
Any faults drawing significant current will hardly draw the line at just below the fused value. If you're worrying about that then you really need something to do.