Wire Cost

About

• SER cable is preferred, no conduit needed [1]. XHHW and THHN can be used but require conduit.
• NM-B house wire is specified for 60C by the NEC, but it can withstand 90C. [2]
• 2AWG is rated for 95A at 60C, 1 AWG is rated for 110 at 60C [3]
• USE-2, RHW-2 and RHH - sunlight, heat, moisture resistant [4]
• Aluminum ampacity - 1/0 aluminum does 100A at 60C. Good chart of wire types and their T resistance [5]
• Terminations at panels must be rated at 60C - [6] - thus you must specify wire for 60C. For example, if you want 100A, oversize 100A 90C wire to something larger at whose 60C rating you get the required ampacity.
• THHN to subpanel - yes if in conduit - [7]
• Standard practice - individual THHN through conduit or NM-B through stud holes [8]
• Romex or BX wire can be run without conduit - [9]
  • Romex goes up to 2 awg [10]

Cost

• THHN 6 ga copper - $1/ft [11]
• 6/3 NM-B is $5/ft [12] or [13]
• 2/3 NM-B is $9/ft [14]
• 4/0 is same price - [15] or [16]
• 1/0 aluminum is 100A and $2.50/ft [17]