Originally Posted by Randell Tarin
The panel is rated at 200 AMPs. I never said I was pulling 200 AMPs. It's more like 150 AMPs. So, you're right; it works just fine.
The OP never said what his final load was going to be. THAT will determine the size of his conductor at 325 feet (not 600 feet).
If the wire is protected by a 200 amp over current protection device, it must be a minimum of 4/0 aluminum wire. It doesn't matter if your pulling 3 amps. See table 310.15 B 6. See also table 310.16. Use the 75C column.
You are correct, the load will determine the voltage drop and thus the conductor size for his 325 foot run. But it no case will the feeder be allowed to smaller than that required for his over current protection device. For a service feeder, it is common practice to use the service size to calculate voltage drop as loads can and do change in dwelling units. In the OP's case that would be 100 amps. A 4/0 aluminum wire would give him a 2.5 percent voltage drop on the feeder if his load was 100 amps.
Your feeder works just fine for you. But it is not in compliance with the National Electric Code, and you would have been required to replace the 2 ungrounded conductors (600 feet of wire) had the inspector been doing his job. Unless it is a lateral, installed and owned by the POCO as Petey mentioned.
It is never prudent, nor morally justifiable for an electrician to tell Do It Yourself people "what they can get away with." We must tell them what is correct and code compliant.