Q. I am going to use the AC powered tubular motors for the roller blinds in our new building home, how should the electrician pre-wire the main AC power cable?

A. You can choose either left hand or right hand according to which side is easy to pre wire the power cable, you need one switch to control the power on or off (isolation) as well, this switch doesn't control the blind up or down, it's pure just for the isolation purpose . If you want to drill a hole on the window jamb, then the hole is better to close ( like 15mm ~20mm ) to the window glass to avoid the position where the blind bracket will be installed, it can be 55mm~60mm down from the top ( molding ) ,  if the bracket is larger like for the dual roller blind one, then you need to be careful, it's better to drill a hole from the top ( Molding ), then it can be 30mm from the left or right hand side jamb,but sometimes it's difficult or impossible to drill a hole from the top since there may be a steel beam something like that. The size of the hole and the space behind of the hole should be big enough to push the power cable back to inside of the hole after electrician finish the wires connection, because the rated power and rating A of the AC powered tubular motor are quite small,  so you can choose 1 mm2   or 0.75 mm2   power cable to easily push the connected cable back to hole.