Should I finish installing this porch light?
October 31, 2022 2:10 PM Subscribe
I've partially completed work on replacing a porch light fixture for my home, which is on an old knob & tube circuit. While K&T wiring is indeed potentially dangerous if manipulated, I also know there's a lot of misinformation out there about just how dangerous it is. Having mostly completed the job, I'm now debating whether I should go ahead and finish it, or dive into a much more complex rewiring with Romex. I'd appreciate any help thinking it through!
I have a good working knowledge of electricity and a reasonable DIY-er level knowledge of household wiring. A few years ago, my porch light burned out, and on trying to replace it, I discovered that the very old light fixture had rusted shut such that I couldn't access the bulb. I determined I'd need to replace the whole fixture. Normally this would be a pretty simple job, but the house still has some knob & tube wiring, and the porch light is on the K&T circuit. Consistent with that era of wiring, there was no junction box at the fixture, just two K&T wires poking through a hole in the plaster into the base of the old fixture. Since the job was slightly more complex than I'd hoped, I back-burnered it. Suffice to say, we've been living without a porch light ever since.
Flash forward to today, and we're trying to get our house ready to sell, and a lack of a porch light is definitely not ideal. I finally went ahead and installed a low-profile pan junction box to double as both a safer site for electrical connection and a mounting point for the new porch light. Getting it installed securely in the plaster ceiling turned out to be a bit of a chore, but it's mechanically very secure now. About 2-4 inches of the two K&T wires, which are protected by cloth insulation, enter through one of the punch-outs in the back of the junction. I connected them up to the new light fixture's wires with wire nuts (it being K&T, there is of course no ground wire available though) and mechanically at least everything is stable.
Back when I first took the porch light out of service, I went ahead and removed the light switch controlling it, just as an extra safety measure to ensure no power would ever flow to it while I was "in the process of replacing it" (read: not touching it for several years). Now that I'm done, though, I'm debating whether to go ahead and install the light switch again. I've been assured by multiple electricians in the past that knob & tube wiring is really quite safe as long as you don't touch it, and even some minor work at a fixture is safe. But I did have to do some manipulation of the protruding K&T wires in order to get the junction box & fixture installed, and I could clearly see that some of the cloth insulation was degrading before my eyes. (Just the outer layer, though: there are at least 2 layers of cloth insulation, the outer of which appears to have been deliberately removed from the last several inches of one of the two wires back during the original wiring.) While I couldn't see anything concerning that I couldn't keep well protected, I'm having visions of just a little bit of movement of wiring inside the ceiling of my porch leading to enough degradation to cause a spark and a fire. I really don't think that I moved the wires around enough to cause any problems, and so I'm not sure if I'm being reasonable to worry about this, or if it's just a manifestation of anxiety.
If I scrap the work I've already done, my alternative is basically to run Romex to the porch from our main panel in the basement. This would be a significant job, as I'd have to fish the Romex into position and probably make a mess of several interior and exterior walls. There's a K&T-wired electrical outlet directly in the path I'd need to take, so this would very easily escalate to needing to just go ahead and fully rewire the entire K&T circuit, which definitely requires an electrician and more money than I have. The alternative alternative is to leave the porch light unwired and just disclose that it's nonfunctional and needs rewiring when we sell the place.
You are not my electrician, but if you are an electrician or someone else experienced working with household wiring, especially old wiring, I'd appreciate your thoughts on this. Based on what I've described, does this have you screaming to leave it alone and rewire? Or is this pretty much what you'd do with your house?
I have a good working knowledge of electricity and a reasonable DIY-er level knowledge of household wiring. A few years ago, my porch light burned out, and on trying to replace it, I discovered that the very old light fixture had rusted shut such that I couldn't access the bulb. I determined I'd need to replace the whole fixture. Normally this would be a pretty simple job, but the house still has some knob & tube wiring, and the porch light is on the K&T circuit. Consistent with that era of wiring, there was no junction box at the fixture, just two K&T wires poking through a hole in the plaster into the base of the old fixture. Since the job was slightly more complex than I'd hoped, I back-burnered it. Suffice to say, we've been living without a porch light ever since.
Flash forward to today, and we're trying to get our house ready to sell, and a lack of a porch light is definitely not ideal. I finally went ahead and installed a low-profile pan junction box to double as both a safer site for electrical connection and a mounting point for the new porch light. Getting it installed securely in the plaster ceiling turned out to be a bit of a chore, but it's mechanically very secure now. About 2-4 inches of the two K&T wires, which are protected by cloth insulation, enter through one of the punch-outs in the back of the junction. I connected them up to the new light fixture's wires with wire nuts (it being K&T, there is of course no ground wire available though) and mechanically at least everything is stable.
Back when I first took the porch light out of service, I went ahead and removed the light switch controlling it, just as an extra safety measure to ensure no power would ever flow to it while I was "in the process of replacing it" (read: not touching it for several years). Now that I'm done, though, I'm debating whether to go ahead and install the light switch again. I've been assured by multiple electricians in the past that knob & tube wiring is really quite safe as long as you don't touch it, and even some minor work at a fixture is safe. But I did have to do some manipulation of the protruding K&T wires in order to get the junction box & fixture installed, and I could clearly see that some of the cloth insulation was degrading before my eyes. (Just the outer layer, though: there are at least 2 layers of cloth insulation, the outer of which appears to have been deliberately removed from the last several inches of one of the two wires back during the original wiring.) While I couldn't see anything concerning that I couldn't keep well protected, I'm having visions of just a little bit of movement of wiring inside the ceiling of my porch leading to enough degradation to cause a spark and a fire. I really don't think that I moved the wires around enough to cause any problems, and so I'm not sure if I'm being reasonable to worry about this, or if it's just a manifestation of anxiety.
If I scrap the work I've already done, my alternative is basically to run Romex to the porch from our main panel in the basement. This would be a significant job, as I'd have to fish the Romex into position and probably make a mess of several interior and exterior walls. There's a K&T-wired electrical outlet directly in the path I'd need to take, so this would very easily escalate to needing to just go ahead and fully rewire the entire K&T circuit, which definitely requires an electrician and more money than I have. The alternative alternative is to leave the porch light unwired and just disclose that it's nonfunctional and needs rewiring when we sell the place.
You are not my electrician, but if you are an electrician or someone else experienced working with household wiring, especially old wiring, I'd appreciate your thoughts on this. Based on what I've described, does this have you screaming to leave it alone and rewire? Or is this pretty much what you'd do with your house?
There apparently are GFCI protected light switches, although I didn’t see any that didn’t include a plug outlet, that doesn’t mean they don’t exist, and even if that’s all you can find, you could also glue in one of those prong shields if it turns out there's no way of keeping the outlet from getting power when you install it.
I would consider that GFCI protection more than made up for the drawbacks of knob and tube.
posted by jamjam at 3:12 PM on October 31, 2022 [1 favorite]
I would consider that GFCI protection more than made up for the drawbacks of knob and tube.
posted by jamjam at 3:12 PM on October 31, 2022 [1 favorite]
Provided there aren't any issues with using one on a K&T circuit, and there are options for your panel, I'd prefer a GFCI circuit breaker.
posted by snuffleupagus at 3:16 PM on October 31, 2022 [1 favorite]
posted by snuffleupagus at 3:16 PM on October 31, 2022 [1 favorite]
Response by poster: GFCI breaker for the K&T circuit is a great idea, thanks! Unfortunately because of the design of the porch (it's really more of a covered entryway), a solar-powered light would be tricky, though not impossible, to install. The point about a plastic or ceramic collar is also really good, I think I'll go ahead and take the fixture down to put something like that in.
posted by biogeo at 4:38 PM on October 31, 2022
posted by biogeo at 4:38 PM on October 31, 2022
Response by poster: Actually, I wonder if an arc fault (or combination arc/ground fault) interrupter might be a better idea? Or is that likely to just nuisance trip too frequently on a K&T circuit?
posted by biogeo at 4:46 PM on October 31, 2022 [1 favorite]
posted by biogeo at 4:46 PM on October 31, 2022 [1 favorite]
I was also wondering, and am not sure. It would certainly be cheaper peace of mind to purchase from an electrician (including selecting the appropriate breaker) than rewiring the branch (or maybe even an estimate on re-wiring the branch, given it's pretty cut and dried and you can send a photo of the panel to get a bid). And having that invoice to show might help in case an oversensitive property inspection flags it.
I picked up a home inspection certification during the pandemic as a side hustle idea (and out of boredom), and both K&T wiring and retrofits to the panel are the things the training calls out for closer attention.
I know it's ugly when you're staring right at it, but if it's up against a wall a painted wiremold conduit tends to disappear outside, and you can use the really itty bitty ones for 12v solar. Or if it really bothers you there's probably enough clearance under very narrow c-profile or corner wood or plastic trim.
posted by snuffleupagus at 5:35 PM on October 31, 2022 [1 favorite]
I picked up a home inspection certification during the pandemic as a side hustle idea (and out of boredom), and both K&T wiring and retrofits to the panel are the things the training calls out for closer attention.
I know it's ugly when you're staring right at it, but if it's up against a wall a painted wiremold conduit tends to disappear outside, and you can use the really itty bitty ones for 12v solar. Or if it really bothers you there's probably enough clearance under very narrow c-profile or corner wood or plastic trim.
posted by snuffleupagus at 5:35 PM on October 31, 2022 [1 favorite]
(not to imply the pandemic is over)
posted by snuffleupagus at 5:41 PM on October 31, 2022
posted by snuffleupagus at 5:41 PM on October 31, 2022
One option, since it’s a janky old porch to begin with, is to just run a new circuit out from the basement in conduit. No fishing of wires, and things go together really fast. I have this in my porch right now as a temporary solution until we get to the bigger remodel in the future.
posted by rockindata at 5:58 PM on October 31, 2022 [4 favorites]
posted by rockindata at 5:58 PM on October 31, 2022 [4 favorites]
I've been assured by multiple electricians in the past that knob & tube wiring is really quite safe as long as you don't touch it, and even some minor work at a fixture is safe.
K&T wiring is so old the insulation can crack and disintegrate even from road vibration or something. It really is something that should be replaced where possible though if I was selling a house I'd let the new owners worry about it.
Actually, I wonder if an arc fault (or combination arc/ground fault) interrupter might be a better idea? Or is that likely to just nuisance trip too frequently on a K&T circuit?
Will your panel handle a Arc Fault breaker? Does the K&T go right into the panel? Arc fault protection is a theoretically good idea but it's possible the breaker will never set (even if the insulation is otherwise in good shape it was pretty common for electricians to just grab whatever neutral was passing by when wiring a circuit and mixing like that will prevent an Arc Fault device from setting). Suddenly you know you have a problem that you could previously be ignorant about.
If there are any more modern circuits available near the porch I'll note that porch lights are not required to be switched. You can just grab power from anywhere, run an extension to a porch light location and then install a fixture with either a motion sensor or photoeye (comes on when it is dark) or both. For _reasons_ this is what I've done on one of my porches and it works fine. Modern LED fixtures draw so little power it doesn't make much difference if they just burn 12 hours a day. Complication: you don't want to be fishing a cable through a wall cavity with K&T wiring.
posted by Mitheral at 7:18 PM on October 31, 2022 [2 favorites]
K&T wiring is so old the insulation can crack and disintegrate even from road vibration or something. It really is something that should be replaced where possible though if I was selling a house I'd let the new owners worry about it.
Actually, I wonder if an arc fault (or combination arc/ground fault) interrupter might be a better idea? Or is that likely to just nuisance trip too frequently on a K&T circuit?
Will your panel handle a Arc Fault breaker? Does the K&T go right into the panel? Arc fault protection is a theoretically good idea but it's possible the breaker will never set (even if the insulation is otherwise in good shape it was pretty common for electricians to just grab whatever neutral was passing by when wiring a circuit and mixing like that will prevent an Arc Fault device from setting). Suddenly you know you have a problem that you could previously be ignorant about.
If there are any more modern circuits available near the porch I'll note that porch lights are not required to be switched. You can just grab power from anywhere, run an extension to a porch light location and then install a fixture with either a motion sensor or photoeye (comes on when it is dark) or both. For _reasons_ this is what I've done on one of my porches and it works fine. Modern LED fixtures draw so little power it doesn't make much difference if they just burn 12 hours a day. Complication: you don't want to be fishing a cable through a wall cavity with K&T wiring.
posted by Mitheral at 7:18 PM on October 31, 2022 [2 favorites]
Combination arc fault is the kind of breaker that would detect any theoretical problem which could occur with those wires and turn off. You do not need GFCI, though it would also not hurt.
I would just install the switch and move on, though.
posted by flimflam at 7:46 PM on October 31, 2022 [1 favorite]
I would just install the switch and move on, though.
posted by flimflam at 7:46 PM on October 31, 2022 [1 favorite]
Response by poster:
We actually had the main service connection and panel upgraded when we moved in five years ago, as the old panel was kind of overloaded. So the panel itself is pretty new and high quality, and I think an arc fault breaker should be possible. At some point in the more distant past, presumably when it was still code-acceptable to do this, someone installed a junction box in the basement for the K&T circuit to terminate in, and that box is connected to the main panel via armored BX cable. (Our house is like a weird little history lesson in 20th century electrical wiring, we have a little bit of almost everything.) So the main panel itself doesn't have any K&T wiring terminating directly into it, fortunately, which makes it more feasible to do that kind of work. If the K&T wiring went right into the panel, there's no way I'd consider doing anything with it.
Thanks also to those of you suggesting running some low-profile conduit with new Romex wiring. I'd thought about that but rejected it because I'd still have to get the wiring to the switch inside, but the point about an exterior light not needing to be directly switched might make that a more viable option.
All of these answers have been extremely helpful so far in letting me think through my options! Very much appreciated all of you.
posted by biogeo at 8:08 PM on October 31, 2022
Will your panel handle a Arc Fault breaker? Does the K&T go right into the panel?
We actually had the main service connection and panel upgraded when we moved in five years ago, as the old panel was kind of overloaded. So the panel itself is pretty new and high quality, and I think an arc fault breaker should be possible. At some point in the more distant past, presumably when it was still code-acceptable to do this, someone installed a junction box in the basement for the K&T circuit to terminate in, and that box is connected to the main panel via armored BX cable. (Our house is like a weird little history lesson in 20th century electrical wiring, we have a little bit of almost everything.) So the main panel itself doesn't have any K&T wiring terminating directly into it, fortunately, which makes it more feasible to do that kind of work. If the K&T wiring went right into the panel, there's no way I'd consider doing anything with it.
Thanks also to those of you suggesting running some low-profile conduit with new Romex wiring. I'd thought about that but rejected it because I'd still have to get the wiring to the switch inside, but the point about an exterior light not needing to be directly switched might make that a more viable option.
All of these answers have been extremely helpful so far in letting me think through my options! Very much appreciated all of you.
posted by biogeo at 8:08 PM on October 31, 2022
I would just direct wire, and I have AFCI protection on my outdoor outlets, and I would rip it out if I could - it nuisance trips far too often, and IMO other than the really necessary spots, 120v AC power is not going to kill most people vs the amount of nuisance trips, which sours people like me on the product. IMO it's like if your bicycle tires went flat on a regular basis to keep you from going over 20mph.
posted by The_Vegetables at 7:27 AM on November 1, 2022
posted by The_Vegetables at 7:27 AM on November 1, 2022
"and we're trying to get our house ready to sell" Will the house pass the buyer's inspection with knob and tube? I know it wouldn't here (Kenton County, Kentucky).
posted by tizzie at 10:25 AM on November 1, 2022 [1 favorite]
posted by tizzie at 10:25 AM on November 1, 2022 [1 favorite]
Response by poster: K&T wiring is grandfathered-in in my locality. As I've had explained to me by a local electrician, you can't modify K&T wiring by extending it or doing the kind of reworking with BX wiring I described above (if that sort of work was done some time in the past, it's also grandfathered-in as long as it was code-compliant at the time though). The presence of K&T does have to be disclosed in the seller's report, but many of the homes in my area are 100+ years old and some K&T wiring is still pretty common. In a perfect world I'd go ahead and have an electrician pull out all the K&T in our house (if I could have afforded it, I would have done it when we moved in) and upgrade it to Romex, but since that work also involves tearing open & repairing plaster & lath walls, it's been prohibitively expensive for me. Some buyers do shy away from K&T, but since it's so common in our area I think most just accept that there's a good chance they'll need to live with it if they like the house otherwise. That was our experience when we moved in a few years ago, anyway.
Short answer, yes, K&T should pass inspection in our area, as long as any visible wiring appears safe.
posted by biogeo at 2:46 PM on November 1, 2022
Short answer, yes, K&T should pass inspection in our area, as long as any visible wiring appears safe.
posted by biogeo at 2:46 PM on November 1, 2022
Original knob and tube wiring may be grandfathered in in your locality, but updates almost certainly aren’t - especially not home handyman jobs. In my locality, this would require a building permit, which would require updating the electrical. This may be one of those situations where it will be more financially beneficial in the long run (eg. house selling cost) to do the job the right way rather than the expedient way.
posted by eviemath at 2:56 AM on November 2, 2022 [1 favorite]
posted by eviemath at 2:56 AM on November 2, 2022 [1 favorite]
AFCIs aren't about protecting people, at least directly, they are to prevent electrical fires. When they first came out quality control wasn't the greatest but with new stuff it's been my experience that 50% of the problem is poor installations, 49% poor quality often unlisted equipment, 0.9% detecting damage (nails hitting wire in the wall mostly) and about 0.1 defective breakers.
Combo devices especially (GFCI +AFCI in a single breaker) have really forced residential electricians to step up their game because they can't get away with loose splices, overdriving staples or loose back stabs that previously would take years to spark a fire and now won't let a breaker set.
At some point in the more distant past, presumably when it was still code-acceptable to do this, someone installed a junction box in the basement for the K&T circuit to terminate in, and that box is connected to the main panel via armored BX cable.
OP your panel being only five years old means supply issues not withstanding you should be able to swap a AFCI breaker in. Your system has probably been updated at least twice as the orginal instalation would have had a fuse panel rather than a breaker panel. Making a transition to BX/NMD (Loomex) is still a perfectly valid way to handle K&T wiring barring local admendments baring it. It certianly isn't unsafe IMO if done properly.
posted by Mitheral at 5:28 AM on November 2, 2022 [2 favorites]
Combo devices especially (GFCI +AFCI in a single breaker) have really forced residential electricians to step up their game because they can't get away with loose splices, overdriving staples or loose back stabs that previously would take years to spark a fire and now won't let a breaker set.
At some point in the more distant past, presumably when it was still code-acceptable to do this, someone installed a junction box in the basement for the K&T circuit to terminate in, and that box is connected to the main panel via armored BX cable.
OP your panel being only five years old means supply issues not withstanding you should be able to swap a AFCI breaker in. Your system has probably been updated at least twice as the orginal instalation would have had a fuse panel rather than a breaker panel. Making a transition to BX/NMD (Loomex) is still a perfectly valid way to handle K&T wiring barring local admendments baring it. It certianly isn't unsafe IMO if done properly.
posted by Mitheral at 5:28 AM on November 2, 2022 [2 favorites]
AFCIs aren't about protecting people, at least directly, they are to prevent electrical fires.
Electrical fires IMO just aren't common enough for the trouble of them, and haven't been basically since romex was invented. Modern fire departments handle about 1-2 fires a day, and that's often multiple crews/fire stations responding to the same fire.
That's why they have shifted from being fire departments to basically dealing with car crashes all day long.
I'm not saying that fires don't suck for individuals, and can be deadly, but that's true of lots of things. The incremental gain of AFCI/GFCI overkill isn't accomplishing much.
posted by The_Vegetables at 7:59 AM on November 2, 2022
Electrical fires IMO just aren't common enough for the trouble of them, and haven't been basically since romex was invented. Modern fire departments handle about 1-2 fires a day, and that's often multiple crews/fire stations responding to the same fire.
That's why they have shifted from being fire departments to basically dealing with car crashes all day long.
I'm not saying that fires don't suck for individuals, and can be deadly, but that's true of lots of things. The incremental gain of AFCI/GFCI overkill isn't accomplishing much.
posted by The_Vegetables at 7:59 AM on November 2, 2022
There's statistics, and then there's not wanting to become one. But, perhaps a choice for the next owner.
posted by snuffleupagus at 6:18 AM on November 3, 2022 [1 favorite]
posted by snuffleupagus at 6:18 AM on November 3, 2022 [1 favorite]
This thread is closed to new comments.
In terms of alternatives, maybe you could install a solar powered rechargable unit, the kind that has a little remote panel hanging off the side of the house? I know they make sconces, pendant and carriage lights in that style, not sure about ceiling mounts. There are bulb kits too, you might be able to fit one into the fixture you have.
The circuit should be fault protected if it isn't already.
posted by snuffleupagus at 2:47 PM on October 31, 2022 [1 favorite]