I am rewiring several fixtures in the basement. Can I attach electrical cables to the underside of the rafters in the basement?
Joists actually, but I get you. Otherwise, only if you want to nick them & have to re-wire after every electrocution. To do wire on the joist bottoms you have to use Armored Cable or some kind of approved conduit. Really just not a good idea, much easier yes but definitely not better. Plus, drilling through the center of the joists isn't that bad & the basement could be finished in the future with less corrections to make.