5

enter image description hereenter image description hereWe have a beautiful house built in the 1920s. I was changing over a light fixture when I found that the ceiling of the room is wired with rubber wrapped 12(?)gauge wire that goes into a metal pancake box attached to what I believe is a ceiling joist. Based on current code I think it's overfilled as it has one pass through common wire (that goes in and out without any termination), the common line, and 2 load wires that are spliced together (I'm not sure why there are 2 loads). The visible insulation appears to be in good condition. If I'm just changing a fixture I know I'm not required to make this code compliant.

My understanding with the reason for the code is excess heat causing damage to the conductors leading to insulation failure --> fire. The fixture is a chandelier that will be 3 feet lower with LED bulbs so heat and wattage should be much better than it ever was before.

My questions are:

  1. Can I cut the pass through wire and wire-nut it? I figure yes but I wanted to make sure.

  2. The box covering the ceiling has ample room to leave wires in it, to my mind that would be safer from a heat standpoint. I don't know if that's code compliant or stupid for a reason I'm not aware of.

  3. Replacing the pancake is possibly doable but I'd then have to cut into the wood rafter to make room. I'd prefer not to do that out of concern for opening up a can of worms. I'm wondering if I need to replace the box.

  4. Current wiring does not have a ground line. If I attach a ground to the metal box does that provide any safety gain?

Thanks for your help. Elmo

  • Are you asking #1 because you intend to change the box, or what? Is #2 asking about using the fixture housing as part of the box? What's the question for #3? – isherwood Mar 29 '17 at 17:59
  • Thank you for replying. The mount for the fixture requires a thin, long, steel bar that sits flush with the ceiling. The way the wires enter the box they will run straight into the bar. If I cut and re-splice the pass through wire I can move it so there isn't a sharp bend which I think is safer. Also I will have to cut/splice in order to remove the box if I did that. For #2 - essentially yes. The box is only 0.5in deep. I'd like to let the wires sit within the enclosure a bit (I doubt I could pack them into the pancake as is). #3 - basically do I need to do this? – Elmo Mar 29 '17 at 18:26
  • 2
    Remember that to cut and splice a wire there must be slack from somewhere. Cutting a wire with no slack opens a can of worms as you'll need to double splice and probably need a new nearby junction box. – Tyson Mar 29 '17 at 19:18
  • @Elmo, please edit your post to add all that information. It shouldn't be buried in a comment. Thanks. – isherwood Mar 29 '17 at 19:20
  • 1
    A "saddle box" might be used here to provide more volume in the box without having to cut into the ceiling joist. homedepot.com/p/… – Jim Stewart Mar 29 '17 at 20:37
1

On this site there have been discussions from knowledgeable people about the importance of having every hot and its paired neutral conductor in the same cable or conduit. This is so the net time varying magnetic fields surrounding the wires are zero and so will not induce currents in surrounding metal. Induced currents cause heating of the metal.

I think you should find out what this pass through wire is being used for. This seems like a situation requiring a current clamp meter to find out the current (including the direction) in each wire under load. You may really need an expert electrician to look at this.

0

Well, that's a first I've seen and I've seen a lot...but a pancake box with NO 8/32 side threads?

Looks like the original original fixture was hung from the center all-thread and was actually probably fed by gas, not electricity. At some point, it was converted over. But all that is speculative and I digress.

I see no point in adding a ground and changing the box out as long as the fixture is secured properly. I'd first remove the center all-thread if possible, then use long wood screws to grab into the ceiling joist to secure the chandelier.

If you really had to yank the box out and replace with new wiring, then best to replace the entire circuit, switches and all. Little more work there. The new box could be a inch 1/2 deep and 3"or 4" diameter and needs to be rated for the weight of the chandelier.

Edit: Regarding the unbroken loop. My gut feeling is the electrician who wired the light was, and how to say this politely, going over and beyond. A unbroken loop is more reliable. Heck, its even crossed my mind to do it in my practice, but it's just not realistic. But again, I digress. In the box is a one 3 wire with extra conductor cut off to save space which gives the impression of a 2 wire. In situations like this the 3 wire provides a continuous hot or neutral at the other junction. No worries.

  • I basically worked with it and have the fixture mostly installed now. One question. The fixture is heavy, 85lbs in total. I've got one 3/16 toggle bolt through the wood holding the pancake box (it feels 1 inch thick, is it a joist or a piece of wood bridging the joists?) and 3 more into the plaster and lathe. I would guess the plaster and lathe is 3/4 thick based on what I went through. I couldn't get into a second ceiling joist no matter what I tried. I can further reinforce it into that piece of wood in the pancake. Would you do anything else? – Elmo Apr 2 '17 at 3:15
  • Doesn't sound good. Never use the wood lath as a support, and absolutely not the plaster. The 1" board is probably bracing or intentionally put in place to support a fixture. Not gonna beat around the bush on the importance of safety here. – Kris Apr 2 '17 at 9:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.