The maximum number of number 6 AWG THW conductors allowed in a 1 inch PVC schedule 40 conduit is _____?

The maximum number of number 6 AWG THW conductors that can be accommodated in a 1-inch PVC schedule 40 conduit is determined based on the National Electrical Code (NEC) and the fill capacity rules for conduits. According to NEC guidelines, specific tables outline the allowable fill percentages for different conduit sizes, considering conductor size and type.

For a 1-inch diameter PVC conduit, the permissible fill percentage is generally 40% for conductors. By examining the NEC fill tables, we find the total cross-sectional area for a 1-inch conduit and compare it with the area occupied by each number 6 AWG THW conductor.

Since the area occupied by each number 6 AWG conductor is known, the calculations confirm that four of these conductors can fit within the allowed fill space without exceeding the maximum capacity. This ensures that the conductors are not overly crowded, which could lead to overheating and other safety hazards.

Therefore, the correct answer reflects the NEC's guidelines for optimal and safe installation practices, highlighting the allowance for four number 6 AWG THW conductors in a 1-inch PVC schedule 40 conduit.