Ultimately for type nm romex this is directly referenced in the 2011 nec 334 23 but only points you to comply with 320 23 type ac as does 330 23 type mc.
Running wiring in the attic.
You must protect all cables running perpendicular and atop the joists.
Concealed knob and tube wiring shall not be used in the following.
If you drill holes in the joists and run wire through those holes you ll be disturbing the insulation.
This is usually a moveable piece of drywall or plywood that covers a rectangular hole in.
5 hollow spaces of walls ceilings and attics where such spaces are insulated by loose rolled or foamed inplace insulating material that envelops the conductors.
The presumption is that the cable run will be looped from one box location down or up into a basement crawlspace or an attic then across floor joists before entering the stud cavity where the next box is located.
A the upper faces of ceiling joists.
Raul no this is not a standard practice and is most likely the result of improper installation of electrical attic wiring.
How to run wire through an attic step 1.
To run the wires inside rigid conduit you ll need a hacksaw a pipe bender capable of bending 1 2 in.
Attics with permanent access stairs ladder.
Rigid conduit with an outside diameter of 3 4 in and a fish tape long enough to reach through the buried pipe.
Yes this should be corrected and it would be good to have the wiring and all the circuit connections inspected as well.
Cables shall not be run on or across.
The lower faces of rafters in attic or roof spaces where the vertical distance.
If the wires are within 7 of the attic access hole or along any attic flooring you ll need.
Between the joists and the rafters exceeds 1 m i so where the cable is running under the rafters the rafters have to be 1m above the joists.
Measure the distance between the two sites you want to run wire between and make sure you will have enough wire.
The attic wiring should be protected and secured to ceiling joists or other wood structural supports.
You must protect cables located within 6 of the attic access hole.