How do I relocate and possible extend the cabling for a ceiling light without having access to attic?

Question

In the below picture the black spot in the wall (14' side) is a switch that controls the light (a small chandelier) that hangs of the ceiling off the center of the room (the ex owner had a dinner table there). I need to relocate that light (the black spot at the end of the red arrow line) to the red dot in the below picture. I am not sure if the cable in the attic has any slack there, probably not. I do not have access to attic (or more exactly I am afraid to access it because I might crack the glaze of gypsum that was put on the ceiling to cover an old and ugly design. That probably added some 0.5-3/4" of mud to the ceiling. I would be probably stepping on joists and insulation but I would prefer not to if I have the option. I could use some large sheets of plywood to distribute my weight (tall heavy guy) but I would still avoid the hassle if I could.

I guess I would have two problems here: -first find an acceptable solution to decom the old box and extend the cable to the new spot -install a second box there -challenge with how to attach it to the joists or if there other options I would be curious what they are

The light I am installing looks like this one and its weight is 13 lb

Answer 1

An "old work" style junction box is installed from the finished room simply by cutting a hole in the drywall and inserting the box. The common style clamps to the drywall only but several brands offer a box with internal screws for fixing the box to wooden structure rather than drywall alone. One example is pictured below (photo: homedepot.com). It happens to be rated for fixtures up to 50 pounds so it'll manage your choice just fine.

NEC allows for electrical retrofit work (when the drywall is not cut open and cable is fished blindly through the structure) to skip the cable stapling that is normally required when installing NM-B cable.

You could cut the hole for the old work box in the new location, push new cable from the room into the attic through the existing box, and pull it through the hole at the new location. Much easier said than done, however. Fish rods can help.

You mention that there is an attic, it's just that you prefer not to enter it. If somebody is willing to go up there it'll make the wiring job much simpler. It'll also open the opportunity to delete the existing junction box: NEC requires that junctions remain accessible. If the attic can be accessed then a junction box can be placed there. Code doesn't require that junctions be in places you like entering! ;-)

Answer 2

You can't decom the old junction box without attic access and a lot of luck with cable slack and joist positioning. You'll have to splice the new cable to the old cable in that junction box and put a cover on it and it must remain accessible. You'd have to cut your new light hole and fish the cable to the old box and enter the old box with the proper connector and make your connections. As far as mounting the new junction box, you'll either be under a joist so you could screw right into it or be in between two joists and use a box with the bar that connects to two joists. As a last resort, you could swag chain from the existing box to the new location or use cable molding.

You should really re-consider getting up into the attic. Get a small, lite electrician and pay them... you've done the whole house, take a break and have someone do this.