Lisp to create wiring loop (arc) between selected blocks
Not enough information. Do a Search [there are things here already, for instance, or probably on any number of other sites], but if you don't find anything that does what you want:
Between any number of selected Blocks [I assume not just between 2, but your (arc) in the singular could be interpreted that way]? What are the Blocks like, and to where on them should the arc/loop/whatever connect? Do you want to actually "select" the Blocks [in AutoCAD's meaning of that word], or do you want to Object-Snap to some place on them within the process of drawing the loop? A series of Arcs, or a Polyline of arc segments? Including connection to a switch at one end [or more]? Etc., etc. A sample image or drawing would go a long way.
Kent Cooper, AIA 
@Anonymous wrote:
.... A series of arcs. For example , i want to loop 10 light fittings( blocks or circles) together. Loop from center point of block to next block center point. Is it possible to add such loops when i select those ten blocks, with a provision to adjust the arc radius? ....
....
Another thing I did a while back that you could try [linked to in Post 11 of the thread I posted a "for instance" link to before] is the WA command [that stands for Wiring Arcs] here. It wants you to pick on the Blocks in series [not all at once -- figuring out the order to loop through them could be very challenging], and it snaps to their insertion points. They need to be Blocks, so if you have circular fixture symbols, they should also be Blocks, not Circle entities. You can decide the degree of bulge in the arcs that you want [see instructions in the code], but it uses the same one for each Arc.
Kent Cooper, AIA