CALLING ALL ELECTRICIANS ... !
While working up my materials list for a barn power feeder, I have run into a speed-bump in the form of dueling wire size calculators ...
The specifics of the job are, I intend a 60 amp 240VAC single phase service from main disconnect panel adjacent to my transformer with a 300 run of 3 THHN copper conductors in buried conduit to the barn sub-panel, where a #4 copper ground to a ground rod to provide the discrete ground required by a sub-panel service.
The loads anticipated are a steady state of 4,000 watts if the AC in the office, the freezers, small appliances, all the lights in the place are on and every receptacle has an appliance plugged in and running at one time, and an additional surge of 2,400 watts if I crank up my wire feed welder....
The first calculator inputs 1/2 of the run in its calculation and gives #4 copper wires as a result, the second asks for 100% of the length of the run and returns #2 ....
#1
Wire Size Calculator
#2
Wire Size Calculator
So ... which calculator is correct in this situation?
In addition, in consideration of the high cost of wire I would like to compare the cost of aluminum vs copper for this application.
Another question regarding the service....Would it be better to :
- Run the conductors for the barn sub-panel directly off the busses in the main panel and let them be protected by the 200amp main breaker (this is a feed-thru type breaker panel) and install a 60 amp main breaker at the barn sub-panel...
OR
- Run the feed to the barn off a 60 amp breaker in the main panel and use a load center at the barn....
As usual, all opinions, advice and anecdotes are welcomed ...