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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: John Roberts {JR} on May 13, 2016, 04:07:51 PM
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I have been enlisted by my (86YO) neighbor to take a look at his house wiring. Last winter he had a minor fire (smoke?) incident, and I don't know all the details, but some wire(s) supposedly over heated because they had too much garbage stacked up on top of them?? I do not know that I buy the explanation, but their short term remedy was to cut the wires... ::) Probably stopped using the central heat, and reverted to the old in wall room heaters.
Now that warm weather is arrived, the wiring needs to be restored for the central air conditioning to work... So I promised to go over tomorrow and take a look. I'll know more tomorrow after I get some eyeballs on it. I'll beg off if it looks too dicey, but i'd like to save my neighbor a few bux if i can.
Anything obvious to look for? I think they said it was Romex, so not original (very old) house wiring, but could be a few decades old. There's a sub panel (or two) for the central air maybe 100 feet from the power meter and main panel.
The house was expanded upon, once or twice, which is probably why there are multiple electrical panels.
I ASSume romex is still legal for house wiring?
What could possibly go wrong, burn down a friends house?
JR
PS: BTW his house is better wired than mine with actual grounded outlets in the kitchen. 8)
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I ASSume romex is still legal for house wiring?
No offense intended, but, if you have to ask a question like that -- what exactly are you going to offer your neighbor by looking at his wiring? Even if you gave him some good tips regarding safe use of extension cords, he'll be knocking the next time his house starts on fire, saying "John told me this is how it was done!"... I'd tell him to get an electrician and stay far away from offering anything that could be construed as electrical advice. Just my humble opinion.
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No offense intended, but, if you have to ask a question like that -- what exactly are you going to offer your neighbor by looking at his wiring? Even if you gave him some good tips regarding safe use of extension cords, he'll be knocking the next time his house starts on fire, saying "John told me this is how it was done!"... I'd tell him to get an electrician and stay far away from offering anything that could be construed as electrical advice. Just my humble opinion.
Yes that is the correct advice... and like I said I may beg off if it looks dicey, but my neighbor is not exactly flush with excess cash. I will help him if I can.
The last time I did any DIY house wiring we were using BX, a real PIA compared to the (then) new fangled romex with plastic sheath. We had to cut BX with a hack saw, while being careful not to nick the wires. Even the BX outlets I wired up back in the 60's were grounded, better than my house is now.
Yes, I am ignorant of current NEC minutiae, but i am not stupid (well not extremely stupid, maybe just a little stupid for exposing myself to legal liability just to help a neighbor).
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I am still unconvinced by their explanation of how the original fire/smoke incident occurred... perhaps it was one of those arc-fault events, i have read so much about but never seen. ;D
I should know more tomorrow, or maybe not..
JR
PS: I do ASSume romex is still legal, but the branch may need AFCI or some new technology added (air conditioner compressor, fan blower motor, etc. .
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When I was doing renovations in the 80's of 40's-60's homes we could usually tell what was new construction and what was previous renovation by the amount and type of garbage between the walls.
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My guess is that the root cause of the smoke was trying to save a few bucks. So many people "know better" and get it to work so much cheaper than a real electrician. And everything is just cheeky-until it isn't. It is far easier to get something to work when everything is working correctly than to get it to fail safely and gracefully when something goes wrong. That is where a LOT of my time and cost comes from.
That said, AFCIs are not required or used on AC units in normal circumstances. If wire has "too much garbage" stacked on top of it, it was not installed correctly in the first place. Probably damaged or weakened essentially making it a smaller wire in the hot spot-assuming it was the correct size to begin with.
My policy has been to be hands off unless the resources are there to do the job right-(in this case it sounds like properly installing a new wire from the AC to the panel then thoroughly testing the AC unit before returning it to service). Usually that means the customers ponies up the money-or gets the bank too. I have "contributed" to the resources at times when a truly needy person was in serious danger-perhaps you can find a good qualified electrician that needs to do something nice this week?
Burning the house down might not be so bad-sending your neighbor to an earlier than necessary grave is a very real possibility. I suspect he would not be very agile in case of a fire.
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My guess is that the root cause of the smoke was trying to save a few bucks. So many people "know better" and get it to work so much cheaper than a real electrician. And everything is just cheeky-until it isn't. It is far easier to get something to work when everything is working correctly than to get it to fail safely and gracefully when something goes wrong. That is where a LOT of my time and cost comes from.
I don't get the feeling he did the wiring himself or he would know more about it. I suspect real electricians did the original work, while perhaps not white glove guys.
That said, AFCIs are not required or used on AC units in normal circumstances.
Thanks, I'm still trying to figure out where to use them (in my world).
If wire has "too much garbage" stacked on top of it, it was not installed correctly in the first place. Probably damaged or weakened essentially making it a smaller wire in the hot spot-assuming it was the correct size to begin with.
Yes, I literally have not been inside the room yet to inspect the evidence. I do not buy the simple explanation,,, active wiring should not be out in the open where stuff could be stacked up on top of it...I will know more tomorrow.
My policy has been to be hands off unless the resources are there to do the job right-(in this case it sounds like properly installing a new wire from the AC to the panel then thoroughly testing the AC unit before returning it to service). Usually that means the customers ponies up the money-or gets the bank too. I have "contributed" to the resources at times when a truly needy person was in serious danger-perhaps you can find a good qualified electrician that needs to do something nice this week?
I have been warning them since I agreed to look at this, that I'll bail in a minute if I do not feel confident. I declined several times already before agreeing to "look at it". I understand electricity better than most, but have limited experience with house wiring.
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I've found things in my house wiring that scared me a little... about 10-15 years ago, i noticed that my electric stove burners were not making full heat. Poking around in the cupboard under the stove top i found some wires hanging down that were just loosely twisted together and taped (shiny modern electrical tape, not the old school sticky friction electrical tape)... but no wire nut, and clearly not twisted tight enough. Loose connections like that could easily start a fire. I was lucky I guess (I put a wire nut on it and no problems since).
Burning the house down might not be so bad-sending your neighbor to an earlier than necessary grave is a very real possibility. I suspect he would not be very agile in case of a fire.
I am not sure he has much longer to go with or without my help, but i would like to help him get his air conditioning working again. It's already hot and humid here in MS. I want him to be comfortable in his twilight years.
My hit list is to first get a good understanding of what caused the fire/smoke event. I don't think the air compressor was even running (winter) so obvious suspects are blower motor, and heating element inside the air duct drawing current, in combination with faulty wiring.
If I find evidence where the wires were obviously compromised, I feel confident I can repair that. If i don't feel confident, I'm not going to gamble with their house or lives.
JR
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AFCIs are required in virtually all circuits in a new home by the 2014 code. The only exceptions are bathrooms (??), garages, outside and appliance circuits (including microwaves, etc). The are much better than when first introduced a decade or so ago.
Most near misses that I have seen would have been stopped much quicker with an "arc fault" circuit interrupter. Things like loose wire nuts and even arcing worn out receptacles should be caught. While not required in older homes, imo, they are a reasonable way to protect wiring that may not quite be up to snuff.
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OK, I'm not burning his house down yet...
It's interesting how I get three different stories from talking with the husband and wife both in their '80s and their grown son 50's separately.
It looks like from an abundance of caution, they cut two power feeds going into the blower/heat unit. Even though there is a sub panel right there with all four breakers turned off. They also cut the thermostat wires and anything that looked electrical.
My NCVT (I found it) detects voltage on two of the three cables coming into the top of the sub panel, nothing on the cut wires leaving the panel.
I found the smoking gun (wire)... A length of rather modest gauge romex was literally melted around the copper wire conductors inside.
The wire that melted is supposed to feed the outdoor compressor for the central air conditioning. I checked between the two melted conductors for a short and measured a few hundred K ohm, so no dead short that would explain the melt down...
When I went out to the cut off switch by the compressor. i measured completely open circuit both across the compressor, and the wire leading back into the house (with cut off switch turned off).
So I see several discrepancies,,, the gauge of the wire coming from the compressor cut off switch back into the house is much heavier gauge, than the puny wire in the closet supposedly connected to that. I read a complete open circuit, not a few hundred K but maybe my fingers touched the bare wire in the closet inadvertently.
Now here's where the multiple different versions of what happened comes in. The wife tells me the air conditioning wasn't on when the wire burned up, but the son tells me it happened the first time she turned on the air... That sounds logical, so I believe the son.
They told me nobody messed with the wiring but.... my neighbor used to have an outdoor wood burning heater that he sold off last year. The guy who bought the heater had to get down in the crawl space under the house to disconnect the power to the outdoor wood burning furnace blower.
So funny (wrong gauge) wiring under the house, with a splice down there between the good gauge wire coming from the compressor and the puny wire going up into the closet.
I can see what wire burned, but it is still unclear why exactly... A bad compressor might draw excessive current and over-heat the undersized wire, but that compressor is not that old....
I was told after joking about lightning, that the original compressor was hit by lightning several years back. :o
So now I have several suspects.
Scenario #1: Compressor went bad while sitting over the winter, and melted the undersized wire when first turned on.
Scenario #1A: Compressor hit by lightning again (yes, lightning can hit the same place more than once).
Scenario #2: Good old boy who disconnected wood furnace blower power feed, screwed up the compressor wiring under the house.
My conclusion so far...
A) Original wiring was substandard, the wire run between the closet and under-house splice on the way to the compressor is too small gauge.
B) Compressor may or may not be bad... I do not know easy way to test for that short of applying power.
C) Probably some funny business in the wiring under the house, and this was just the one wire that caught fire.
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Since I don't go down into my own crawl space I'm not going down into his. I advised them to first get an air conditioning service man to test the status of the compressor... Then find a somebody to trace out the wiring under the house and upgrade that. So regrettably I haven't saved him a penny.
They have lived in this town all their lives so surely know people who will do electrician work for pay. They already played their one free card and that didn't work out. 8)
JR
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If the compressor is bad, undersize wiring or poor connections could have contributed to its demise. Motors start hard and don't like undervoltage-undersize wire increases voltage drop and a bad scenario snowballs.
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If the compressor is bad, undersize wiring or poor connections could have contributed to its demise. Motors start hard and don't like undervoltage-undersize wire increases voltage drop and a bad scenario snowballs.
In my judgement, the wire feeding it was definitely undersized, but it apparently worked that way for several years. I don't know how long the undersized section of romex is, a few feet inside the closet alone.
I guess the first compressor start after sitting for the winter may have been even higher current draw than usual.
I need to tag in an air conditioning guy, and a crawl space friendly guy... my work here is pretty much done. It looks like they made the repair more expensive that it would have been if they didn't cut every wire in the closet (including thermostat).
I will try to stay involved enough that they don't repeat any bad practices, like wrong wire gauge. I feel bad because the guy just got out of the hospital, and they do not have spare cash around for such things.
If faulty, they need to replace the compressor with a heat pump so they can heat and cool the house more cheaply, but i don't see any budget for that.
JR
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I was actually on a short break during a continuing ed class for license renewal when I posted earlier. We started talking grounding/bonding and it occurred to me that romex (NM) is constructed with a ground wire located between the two current carrying conductors. When that wire started to melt, it should have shorted and tripped the breaker or blown a fuse fairly quickly. If it kept heating long enough to melt the insulation completely off, there may be a a bonding issue as well that should be addressed. Something you might ask the electrician about so he double checks it-in the interests of keeping your neighbor safe.
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I was actually on a short break during a continuing ed class for license renewal when I posted earlier. We started talking grounding/bonding and it occurred to me that romex (NM) is constructed with a ground wire located between the two current carrying conductors. When that wire started to melt, it should have shorted and tripped the breaker or blown a fuse fairly quickly. If it kept heating long enough to melt the insulation completely off, there may be a a bonding issue as well that should be addressed. Something you might ask the electrician about so he double checks it-in the interests of keeping your neighbor safe.
I think I have them talked into getting a real electrician to sort this out.
They shared a few more anecdotes about strange electrical noises coming from under the house, and some strange theories about how the wire fire started some where else and moved to the closet. I decided to not try to educate them about electricity and stop selling after they said they would get a real electrician to sort out the mysterious under the house wiring situation... 8) I can quit when I'm ahead (an early lesson from sales that stuck).
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I am trying to remember what i saw... the wire was pretty trashed but one end was still connected to the heater/blower assembly and it looked like romex (was) black wire was bonded to pretty heavy duty wire clamp with another big fat black wire, and maybe neutral was soldered (?) to a bus wire???? Inside the melted romex i only recall seeing two copper conductors, not three.
I could dig into this closer, but for now, I will let them sort it out using professional (?) help... This is poor small town MS, so who knows what they'll dig up for an electrician? I may try lurk around some just to make sure he isn't too scary, but i don't really have much say in the matter.
BTW looking at the compressor there was an extra small gauge brown wire coming from the compressor housing and into the basement bypassing the switch box... ???
The funny thing is the compressor may be OK (lets hope),,, just some red neck wiring mischief under the house when that guy unwired the wood heater blower.
JR
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,,, just some red neck wiring mischief under the house when that guy unwired the wood heater blower.
JR
Surely not in Mississippi?
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Never ask an engineer, "what's the worst that can happen?" You will get an answer. ;D
You might check around to see if there are any social services agencies (public or private) that could help them pay for repairs.
Your electric and/or gas utility may be able to direct you. They may not be able to recommend an electrician or HVAC contractor, but they may know an agency that has a relationship with some. Also check with food banks or other agencies; they may have connections with people that can help.
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Just a point of conversation. I have had the fan on the out side compressor unit go bad. The compressor would start out drawing normal current and then clime to just over 50A before the 30A breaker would cut out. This over draw could take a very long time to build up and trip. I strapped an industrial box fan to the top of the condenser unit till the 1/4 hp motor could be replaced.
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It looks like from an abundance of caution, they cut two power feeds going into the blower/heat unit. Even though there is a sub panel right there with all four breakers turned off. They also cut the thermostat wires and anything that looked electrical.
Ironically, by cutting the wires in "an abundance of caution," they actually created a more hazardous condition. Now, should the cutouts/breakers/fuses be reenergized, now they have bare live wires (I assume they didn't tape them off -- their total lack of understanding electricity suggests that they wouldn't) hanging out there. :o
And in the process, they complicated repairs, likely making the repair much more expensive than it could have been.
I think that some basic education in how electricity works may be in order. Not that we'd expect them to do their own wiring, but just so that they know how to stay safe around it. A little understanding goes a long way: it can prevent panic in an emergency, and it helps prevent people from doing stupid stuff out of ignorance. Fear is based in ignorance; understanding conquers fears.
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I have no idea what the electrical code is but I would worry about Romex in a crawl space and what might get under there and decides to chew on the wires. I would hope that they would use properly sized metal clad wire under there.
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Never ask an engineer, "what's the worst that can happen?" You will get an answer. ;D
You might check around to see if there are any social services agencies (public or private) that could help them pay for repairs.
Your electric and/or gas utility may be able to direct you. They may not be able to recommend an electrician or HVAC contractor, but they may know an agency that has a relationship with some. Also check with food banks or other agencies; they may have connections with people that can help.
Sorry if I gave the impression he was destitute, he isn't but, but lives on a tight budget, like so many people today.
A while back I lent him a few thousand dollars to buy a used pick-up truck and he is paying me back a modest amount every month. A couple times he has asked me to hold the check before cashing/depositing, so I can tell he is living month to month. He'll be OK, while a new compressor might put a dent in his finances, I can help him more if he needs it.
He just spent a week in the hospital (he's old) so that hospital bill will probably involve a co-pay.
JR
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Ironically, by cutting the wires in "an abundance of caution," they actually created a more hazardous condition. Now, should the cutouts/breakers/fuses be reenergized, now they have bare live wires (I assume they didn't tape them off -- their total lack of understanding electricity suggests that they wouldn't) hanging out there. :o
The wires are not taped off, and they cut them while energized. Now they are all cold and I trust any would be electrician, will make repairs before resetting the breakers.
And in the process, they complicated repairs, likely making the repair much more expensive than it could have been.
I think that some basic education in how electricity works may be in order. Not that we'd expect them to do their own wiring, but just so that they know how to stay safe around it. A little understanding goes a long way: it can prevent panic in an emergency, and it helps prevent people from doing stupid stuff out of ignorance. Fear is based in ignorance; understanding conquers fears.
I have tried over several years to impart better electrical understanding, but teaching a few 80 YO how electricity works, is not a good use of their or my time... I think they respect my opinion at least a little, but I can't force them to do anything.
I am pleased they will engage a (real?) electrician to undo the mess caused by a good old boy who wasn't.
JR
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I have no idea what the electrical code is but I would worry about Romex in a crawl space and what might get under there and decides to chew on the wires. I would hope that they would use properly sized metal clad wire under there.
I am not holding my breath for BX, but would be relieved to see at least a sensible gauge Romex,,,
The wire that burned up was too small IMO, while probably worked that way for years.
JR
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Just a point of conversation. I have had the fan on the out side compressor unit go bad. The compressor would start out drawing normal current and then clime to just over 50A before the 30A breaker would cut out. This over draw could take a very long time to build up and trip. I strapped an industrial box fan to the top of the condenser unit till the 1/4 hp motor could be replaced.
I am keeping my fingers crossed that the compressor is OK (it's not very old)... the anecdotal evidence suggests the wiring under the house may have been accidentally sabotaged.
In hindsight they are lucky their house didn't burn down. I hope their luck holds.
JR
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I have been enlisted by my (86YO) neighbor to take a look at his house wiring. Last winter he had a minor fire (smoke?) incident, and I don't know all the details, but some wire(s) supposedly over heated because they had too much garbage stacked up on top of them?? I do not know that I buy the explanation, but their short term remedy was to cut the wires... ::) Probably stopped using the central heat, and reverted to the old in wall room heaters.
Now that warm weather is arrived, the wiring needs to be restored for the central air conditioning to work... So I promised to go over tomorrow and take a look. I'll know more tomorrow after I get some eyeballs on it. I'll beg off if it looks too dicey, but i'd like to save my neighbor a few bux if i can.
Anything obvious to look for? I think they said it was Romex, so not original (very old) house wiring, but could be a few decades old. There's a sub panel (or two) for the central air maybe 100 feet from the power meter and main panel.
The house was expanded upon, once or twice, which is probably why there are multiple electrical panels.
I ASSume romex is still legal for house wiring?
What could possibly go wrong, burn down a friends house?
JR
PS: BTW his house is better wired than mine with actual grounded outlets in the kitchen. 8)
I am a bit behind here but...
Actually, Romex (RX) isn't legal for new work these days. What most people mean when they say Romex is NM or non metallic wiring meaning not armored.
So, if it is plastic coated it should be NM. If it is fabric/jute covered that might be RX.
Strange that the wire melted without tripping a breaker.
Also, note that many compressors are actually 240v and a 20a #12 is common.
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I am a bit behind here but...
Actually, Romex (RX) isn't legal for new work these days. What most people mean when they say Romex is NM or non metallic wiring meaning not armored.
So, if it is plastic coated it should be NM. If it is fabric/jute covered that might be RX.
Looking on the WWW there are still people selling wire called "romex", but they also call it "non-metallic" wire, which sounds a little odd to me (wire universally uses metal conductors). They probably call it romex in addition to non-metallic, because people want to buy romex, and the customer is always right.
Strange that the wire melted without tripping a breaker.
Also, note that many compressors are actually 240v and a 20a #12 is common.
yup... The sub-panel right there has breakers (not fuses like my house) and they were all in the off position by the time I got to look inside the closet. My sense is that the breakers did not trip from the fault that melted the wire, but i was not there when it happened, and I get different stories from 3 different people who were there. I think there is another breaker(s) at the main panel feeding the sub panel... my NCVT detected power on two lines coming into the top of the sub panel.
The melted romex was not very heavy gauge wire (definitely not #12). Start up current for a big compressor may be well up there.
The electrician may need to test/replace the breaker(s) too. In light of recent drama AFCI breakers might be useful, while it feels like closing the barn door after the horse is gone.
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I've already begged off the re-wiring gig, since I'm not going to crawl under his house (among other good reasons for me not doing it). I will try to look over the shoulder of the electrician they finally get to do the work, and ask appropriate questions, if i can without being too intrusive.
JR
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I am a bit behind here but...
Actually, Romex (RX) isn't legal for new work these days. What most people mean when they say Romex is NM or non metallic wiring meaning not armored.
So, if it is plastic coated it should be NM. If it is fabric/jute covered that might be RX.
Strange that the wire melted without tripping a breaker.
Also, note that many compressors are actually 240v and a 20a #12 is common.
Sent from my iPad using Tapatalk HD
Romex is not used in new residential construction in MA anymore? Still is in Ohio
Personally I always use BX, it's not that much more.
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Romex is not used in new residential construction in MA anymore? Still is in Ohio
Personally I always use BX, it's not that much more.
I remember working with BX when I was a kid, and it is definitely more labor, but I guess a professional has tools nowadays to cut the armor instead of using a hacksaw like we did.
JR
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Actually, Romex (RX) isn't legal for new work these days. What most people mean when they say Romex is NM or non metallic wiring meaning not armored.
So, if it is plastic coated it should be NM. If it is fabric/jute covered that might be RX.
Romex® is a registered trademark. It was originally owned by the Rome Wire Corporation, a predecessor to General Cable. The brand is currently owned by Southwire. http://www.southwire.com/romex.htm
What many think of as "Romex," properly called nonmetallic sheathed cable, was the stuff sheathed with asphalt-impregnated fabric. Originally, the conductors were rubber-covered with a fabric outer covering; the conductors were bundled in an outer fabric jacket.
As technology progressed, the individual conductors became covered with thermoplastic rather than rubber and fabric, but the outer jacket was still fabric. Sometime in the last 25 years the cable became color-coded, with white designating 14 AWG, yellow 12 AWG, and orange 10 AWG. Prior to that, most was either white or black. (Personal anecdote: a few years after the color coding, I purchased a dusty coil of 12 AWG wire with a white jacket, labeled and priced as 14 AWG. Someone wasn't paying attention.)
Side note: when an equipment grounding conductor was first included in nonmetallic cable, it was sized smaller than the current-carrying conductors. So while the current-carrying conductors may have been 12 AWG, the ground wire was 14 AWG. That is no longer permissible in the smaller gauges; code allows for the larger gauges -- I think 8 AWG and larger, but I could be wrong -- to use an EGC one size smaller.
With further advancements in materials technology, the outer jacket also became thermoplastic.
But it was all still Romex® when made by Rome, General, or Southwire*. And it was all type NM (though the modern thermoplastic version is, technically, NM-B).
Type NM-B -- thermoplastic insulation on the conductors, thermoplastic jacket, kraft paper filler -- is still allowed by the NEC for residential construction.
Many jurisdictions, however, have stricter requirements with a minimum of armored or metallic-clad (type AC and MC) cable or conduit. "BX" is not an official designation (at one time it was a brand), and generically refers to either AC or MC, or colloquially as really old armored cable that may have rubber/fabric covered conductors.
* Just like it's only Kleenex when made by Kimberly-Clark.
P.S. -- the stuff with a fabric jacket isn't legal for new installation partly because the insulation doesn't meet the temperature rating. I believe it is no greater than 60°C. Thermoplastic NM-B is typically rated for 90°C.
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I remember working with BX when I was a kid, and it is definitely more labor, but I guess a professional has tools nowadays to cut the armor instead of using a hacksaw like we did.
JR
Yup. The selection of tools to cut, trim, and otherwise prep BX and MC are much better than days of yore. I hope I never have to use them. ;)
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The EGC size is determined by the breaker protecting the circuit it is part of-in larger sizes it can often be more than one size smaller-sizes commonly used by those on this forum would be the same up through #10, #10 is acceptable up to a 60 amp breaker.
NM has a temp rating of 90 deg C-but is still limited to the 60 deg ampacity column.
Technically, the code doesn't limit NM to resi only-it is restricted by the type of construction-but a wood frame commercial building in an area that is only limited by the NEC proper can use NM. But then code is minimum-local jurisdictions and insurance companies might demand more. My experience is that government entities spending your money are more than happy to include specs way above and beyond NEC minimums.
But none of that helps JR's neighbor!
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A lot of what people call BX these days is actually FMC (Flexible Metal Conduit). MC and AC are for practical purposes nearly the same. I just looked at my NEC 2014 and after reading the sections on MC and AC I can't really tell you what they practical differences are. FMC is the stuff that you can pull new wires into. I've got it all over my 80yo house and it's fantastic because I can replace all the rotten old wire with new THHN2. Just make sure you're using stranded when pulling it into old FMC!
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The EGC size is determined by the breaker protecting the circuit it is part of-in larger sizes it can often be more than one size smaller-sizes commonly used by those on this forum would be the same up through #10, #10 is acceptable up to a 60 amp breaker.
NM has a temp rating of 90 deg C-but is still limited to the 60 deg ampacity column.
Technically, the code doesn't limit NM to resi only-it is restricted by the type of construction-but a wood frame commercial building in an area that is only limited by the NEC proper can use NM. But then code is minimum-local jurisdictions and insurance companies might demand more. My experience is that government entities spending your money are more than happy to include specs way above and beyond NEC minimums.
But none of that helps JR's neighbor!
I am pleased that we are all vertical to debate this dispassionately.
It could be much worse.
JR
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I am pleased that we are all vertical to debate this dispassionately.
It could be much worse.
JR
Yes, we could be on our backs trying to work on our neighbors electrical wiring in a crawl space under a house. :P
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Time for a follow up...
While I wasn't looking they got an air conditioning man in to fix the air conditioner and now it is working, turns out that the wire that burned was not the wire going to the compressor, but a wire going to their old wood burning heater. Apparently if they didn't cut every wire in their closet when the fire happened the air conditioner wouldn't have stopped working.
The wire that caught on fire was a modest gauge romex that IIRC was wired directly into the electric heater/fan in the closet, not to the breaker panel. The breaker for the central electric heat unit may be more than 20A (guess, probably 240V). Apparently this wire going to the blower for the outdoor wood heater was not properly tied off, when the heater was removed (by a non-professional DIY) sometime last year.
I do not completely understand the cause and effect time-line that said the fire occurred coincident with the air conditioner being powered on. It appears there was a quasi-short across the improperly terminated romex that was enough current to char it, but not enough current to trip the probably pretty robust breaker on the heater. I did get three different stories from 3 different people about the event so the fire may have been random waiting to happen, when a butterfly flapped it's wings nearby.
The burnt wire is still unfinished business that they plan to have a real electrician replace (air conditioner guy didn't do electrical work). They have unused breakers in the sub panel, so can wire some proper gauge wire into an actual breaker out to their shed. I strongly advised using a more robust wire than was in there before, but hopefully a real electrician will not repeat the previous bad behavior.
I feel slightly better about the situation as they dodged an expensive repair to the air conditioner, and appear on a path toward a professional electrical repair.
JR
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Time for a follow up...
While I wasn't looking they got an air conditioning man in to fix the air conditioner and now it is working, turns out that the wire that burned was not the wire going to the compressor, but a wire going to their old wood burning heater. Apparently if they didn't cut every wire in their closet when the fire happened the air conditioner wouldn't have stopped working.
The wire that caught on fire was a modest gauge romex that IIRC was wired directly into the electric heater/fan in the closet, not to the breaker panel. The breaker for the central electric heat unit may be more than 20A (guess, probably 240V). Apparently this wire going to the blower for the outdoor wood heater was not properly tied off, when the heater was removed (by a non-professional DIY) sometime last year.
I do not completely understand the cause and effect time-line that said the fire occurred coincident with the air conditioner being powered on. It appears there was a quasi-short across the improperly terminated romex that was enough current to char it, but not enough current to trip the probably pretty robust breaker on the heater. I did get three different stories from 3 different people about the event so the fire may have been random waiting to happen, when a butterfly flapped it's wings nearby.
The burnt wire is still unfinished business that they plan to have a real electrician replace (air conditioner guy didn't do electrical work). They have unused breakers in the sub panel, so can wire some proper gauge wire into an actual breaker out to their shed. I strongly advised using a more robust wire than was in there before, but hopefully a real electrician will not repeat the previous bad behavior.
I feel slightly better about the situation as they dodged an expensive repair to the air conditioner, and appear on a path toward a professional electrical repair.
JR
That’s nice to hear, thank you for the follow up.
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Wow - I wish you were my neighbor John - you are a good kind man!
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I feel slightly better about the situation as they dodged an expensive repair to the air conditioner, and appear on a path toward a professional electrical repair.
Doing things right is usually cheaper than doing things cheaply. 8)
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Doing things right is usually cheaper than doing things cheaply. 8)
Doing things wrong can certainly incur extra costs.
In this case improper treatment of the wiring when disconnecting power from the external wood burning heater, resulted in the melted insulation event (months later) and two service calls.
I still haven't received a straight story about who actually handled that specific electrical wiring task. At this point I am more focussed on who handles it from here.
JR