I am planning to install recessed light in ceiling of my 2nd floor condominium. Here are some facts.

  1. There is truss framing (picture attached) in the ceiling, between my ceiling and the upstairs unit's floor.

  2. There is fiberglass insulation in ceiling.

  3. I live in New Jersey and I don't think there is local code in addition to NEC.

I am planning to cut holes in ceiling for can lights and pull the power source from existing switch which currently controls receptacle. I am thinking to change wiring inside the receptacle to make it always hot and then I will connect my recessed lights to existing switch.

I have some questions.

  1. Given truss type of framing in ceiling, can I just run the cables from one can to other can in straight line or I have to run the cable only parallel or perpendicular to framing ?

  2. Is it OK to run Romex cables through fiberglass insulation ?

  3. NEC requires that Romex cable has to be supported to framing members, within ceiling or walls, every 8 inches (I don't remember exact distance) with staples. - How can support it when I don't have access to the ceiling or walls ? I would have to tear apart lot of ceiling and wall to satisfy NEC requirement.


  • 4
    You don't have to staple when retrofitting in existing construction where it would be onerously destructive to tear things up so you can attach cables.
    – Ecnerwal
    Dec 1 '20 at 0:34
  • 2
    NEC 300.4, D, Exception 2
    – Ecnerwal
    Dec 1 '20 at 0:40
  • 2
    Some cans require minimum spacing from insulation to allow for heat to escape, others have the space built in and you can butt the insulation right up to them. Read up on the cans you're selecting to see which kind you have. You may want to change to the "direct contact" type (if you haven't already selected them) to minimize the effort of moving existing insulation out of the way.
    – FreeMan
    Dec 1 '20 at 15:48
  1. You can run from one can to another in any way that makes sense. Typically this would be done to minimize the cable length. It is easier to run parallel to the trusses and minimize truss crossings (this depends somewhat on your insulation). If you have a single line of recessed can lights this should be an easy run from switch to end, but if you have a grid like I did you should plan the cable route in an S or U shaped pattern.

  2. You can run Romex through fiberglass insulation but you should minimize the runs "through" insulation if possible i.e. don't cut a slot in the insulation and wrap it around the Romex. Poke holes if necessary, insert through it, run over the top or around the side of the insulation. More than Romex interacting with insulation though, be aware of installation safety instructions with the can lights, most of which require minimum clearance between the can and any insulation in the ceiling. LEDs which don't heat up the metal housing quite as much have lower clearance requirements, but be sure to check.

  3. Ecnerwal answered succinctly in a comment:

You don't have to staple when retrofitting in existing construction where it would be onerously destructive to tear things up so you can attach cables. NEC 300.4, D, Exception 2


Don't install cans, use canless LED pucks that are IC rated and come with a junction box.

  • I do like slick design of canless lights but down the road if one of them goes bad for any reason and if I cant find exact replacement, I will have to change all lights for asthetics. With cans, I just need to replace bulb/ retrofit LED light. Dec 2 '20 at 9:57

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