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	Subject - correct wire size Joe M Installing a new main panel in a barn. Barn is located approx. 300 ft from feed source. #2AWG is supplied to the barn. What is maximum main panel amp I can install. Second question: If amp ratings of the breakers in a panel are added together and exceed the main breakers amp rating, Is this a problem? (example; 300 amp main panel has 480 of total amps of all breakers in the panel added together) skynrd First of all if it's a UL approved panel with a 300 amp main breaker that breaker is there to protect the breaker buss which is rated for the main breaker size. If your actual load of all your branch circuit breakers exceed the 300 amps your going to trip the main. As for the wire question is it aluminum or copper. kbsparky Your #2 wire can be connected to a 125 Amp breaker, if you are using copper, or a 90 Amp breaker if using Aluminum. This is assuming you are using a wire rated for 75C See Table 310.16. What is to be housed in this "barn" There are other rules pertaining to proper grounding and bonding that must be adhered to, depending on the use of the barn. blackrd Second question: If amp ratings of the breakers in a panel are added together and exceed the main breakers amp rating, Is this a problem? (example; 300 amp main panel has 480 of total amps of all breakers in the panel added together) no, in general. John A. Peters It goes by the load calculation not the total of the breakers. Look at the examples in the back of every code book.