Instructions to electrician about dedicated line

Chazzbo, the current draw on a 20 amp line is a maximum of 20 amps (then the fuse blows). The actual current draw depends on the equipment being hooked up to it and will generally be much less than 20 amps in any typical home system. You are, I believe, correct in stating that the PS Audio 600 is not designed to handle the maximum amperage a 20 amp line can deliver (it translates to about 2200 watts). But it also won't be able to handel all the amperage a 15 amp line can deliver (about 1650 watts). That's OK so long as the equipment being hooked up toe the PS Audio 600 does not demand more than the 600 can deliver (BTW, you can still use the other outlet on a duplex plug for other things). Why get 20 amps? In my mind, for future upgrades only -- and probably for big power amps only. Sean makes a good point about mixing and matching on a dedicated subpanel.

What if you ever change amps? I put in a whole house surge protector as well. It prevents outside problems from interfering but will not protect you from inside trouble(ie feedback from your a/c compressor). For that reason, I also use a line conditioner/surge protector at the unit. I like using GFIs also.

The answer to the, "Why 15A or 20A circuits" is really a code question. The smallest wiring allowed by the NEC for a power circuit in a residence is 14 gauge with 12 gauge being common. Since a 14 gauge wire will carry 15A, it's typical to install a 15A breaker on a 14 gauge circuit. Likewise with 12 gauge and 20A breakers.

Sean's (and others') suggestion to use 10 gauge wire in a 20A circuit is to reduce voltage drop in that circuit. 10 Gauge wire will carry 30A and could have a 30A breaker installed in the circuit. From a power delivery standpoint (up to 20A, of course), this circuit won't be any different with a 20A or 30A breaker installed. However, one might be able to find a higher quality 20A breaker for the same price as a regular 30A breaker.

The thing to remember is that wire is sized to carry a load and the breaker is sized to protect the wire, not the other way around. So, while it's OK to install a 20A breaker in a circuit wired with 10 gauge wire (your electrician will look at you funny, but what does he know?), it is NOT good (or legal) to install a 20A breaker on a circuit wired with 14 Gauge wire.

Macdonj, thanks for clarifying why i stated what i did. In that respect, you were right on the money. However, i would like to add that i don't personally feel that 10 gauge is sufficient for 30 amp service. Regardless of what most "professionals" will tell you, 10 gauge will produce a very noticeable voltage drop under a 30 amp load if it is anything more than a few feet long. I have measured sizable voltage drops using 8 gauge at lengths of under 20 feet while trying to pull 30 - 35 amps through it. As such, i would consider 10 gauge "adequate" for a 20 amp load using the normal length runs that one might find in a house. 12 gauge should be considered minimum for a 15 amp circuit. That is, if one is looking to reduce series resistance / voltage sag to a minimum.

As i've mentioned before, i'm simply sharing / passing on my personal point of view based on the experiences that i've had. As such, my comments are worth just slightly less than what you paid for them : ) Sean
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Bear: While i can understand your thoughts about using one BIG isolation transformer to feed the A/V breaker box for sake of simplicity, what are your thoughts on using multiple smaller ( 15 - 20 amps each ) yet identical transformers wired in parallel ? Sean
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