Hi All,
I have an old house with some original armored cable circuits and some newer romex ones. One of the old circuits runs much of my kitchen lighting, one bedrooms’ lighting and a few outlets as well – probably too much load, but usually not everything is on at the same time. I had an air conditioner plugged in to this outlet (I know, not a good idea, but it was the only nearby outlet) overnight and woke up to the power off. The circuit breaker now won’t reset – it buzzes for 15-30 seconds and then trips.
My guess is that the A/C unit overheated the old wiring causing a fault – is that a likely occurance?
Could it be just the circuit breaker that went? Is it worth trying to swap that out?
Short of rewiring the house with new runs to replace the Armored Cable, any way I can fix this? I’m not looking forward to some major drywall work in my future.
Any replies greatly appreciated,
Ben
Replies
I'm fairly sure its the breaker--if the wiring had a fault, the CB would be (should be!) off entirely.
To check this out, try swapping the lead with another CB. If it still buzzes, change it---if not, don't tear apart the walls, just disconnect all the connections in that circuit until you find the one that stops the buzzing
In your situation, I would check that all the 15 amp leads are #14 and all the 20 amp leads are #12. usually in old houses with different kinds of wiring, some people just pogue stuff in any old way. I once saw an illegal unit in an attic with a heater fed by SPEAKER WIRE!! and Ive seen other stupid stuff like buried junction boxes and ungrounded 3 prong outlets
James
Edited 9/11/2002 10:36:16 AM ET by EXLRRP
Ben,
Unplug everything on the circuit including the Air conditioner. Then try the breaker. If it buzzes swap it with another breaker in the panel.
In the big picture buy yourself a VOM Volt Ohm Meter. Cheapies are as good as fancy ones for your needs. 10 to 20 bucks.
Go and disconnect the circuit either turn the breaker off or unwire it. Lightbulbs need to be switched off as well. Put the VOM on AC. Touch the VOM leads to the black & white wire of the circuit and check to se there is NO meter reading. If it moves there is AC current still on the lines you are reading. Cure that problem, because you are either looking at the wrong circuit, or you have two breakers feeding the same circuit.
Then after you confirmed there is no AC on the circuit in question, switch the VOM to Resistance and check the circuit again. If the meter moves then check the circuit to see everything is unplugged again. If the meter moves when set to resistance when given a connection between the black wire and either the white or the ground (of the BX armored cable) then you may have a wiring problem.
(PS touch the probes on the VOM to your skin when you have it on resistance. If the needle moves set the resistance to a different setting as you are reading the resistance in your body one sweaty hand to the other.) Remember this when you touch the probes to a circuit you are testing it could give you a false resistance reading.
Most likely you fried an old outlet, or you fried the breaker. Replace the breaker with the appropriate size 15 a for 14 ga, and 20 A for 12 ga wire. The wire determines the size of the breaker.
I replaced all of the old outlets in my home. Get good ones. look for 20A size outlets 110 V. It'll keep you out of the 39 cent bins. Brass connections internally are the prime difference. Hospital grade can cost you up to 8 bucks a piece. (you don't need that) Do a few a night and you'll learn your homes electrical system.
If it is the in-wall wire, use the VOM to trace the circuit throughout the basement & go box to box. Likely it is one bad connection that fried.
PPS If you have the old BX with Fabric over rubber over tinned copper wiring I have a tip. This is an old house if so. But before you start messing with rewiring a connection, clip the old connector off or ease off the old wirenut leaving as much of the original wire as possible. Gently straighten it trying not to flake off the old insulation. Then slide a piece of shrink tubing over the old insulation. You can get shrink tubing at any reputable electrical supply house. It generally has a 600 volt insulation rating.
Here is the part where you need to use your head. I use a match or a butane lighter to lightly shrink the tube in place. But, if you have newspaper insulation in your walls I'd use a heat gun. You could start a fire with a match.
The shrink tubing keeps the old insulation in place and makes it easier for you to rewire the old outlets.
Final subnote. Much of the fabric in this type of wiring is asbestos. Be gentle it will last forever.
Thanks for your kind replies.
I do have a voltmeter and I've been popping out some outlets and checking just as you advised. I don't think there are two breakers feeding the same circuit - once the breaker pops there's no more juice in the line. I did get one very odd reading of 6 volts from one of the supposedly "dead" lines, but besides that, nothing. Once I isolate some of the circuit the breaker acts fine, so I'm assuming that it's ok. Am I right to assume that?
The circuit seems to be wired in a very strange way. As far as I can tell, it's new 14 gauge to the kitchen GFCI, then old armored upstairs to the bedroom where it feeds one light and the plug where I put the A/C on. If I cut it there, no fault, so I'm assuming the A/C outlet is not triggering the fault. Then it goes back down to some more outlets in the bedroom, then my kitchen lights. So currently I'm without kitchen lights.
I'll let you know when I map the circuit further with resistance testing.
Ben
The 6 volt reading is a crappy common (white) connection. Tighten screws and nuts as you find them and keep circuits separate (black & white wires). They only connect in the panel to the same point. You can't use one common wire for two separate circuits. Otherwise you get the Phantom voltage.
If someone ties a common of one circuit to the common of another circuit anywhere except the load center there is some power that leaks back into your disconnected circuit if the original (common) path has some resistance from a bad or marginal connection.
It isn't the old houses that cause problems it is people who don't take the time to fix it or install it right like you are.
> The 6 volt reading is a crappy common (white) connection.
Given that it was 6 volts to a supposedly dead line, it's more likely that the culprit is capacitance between that dead -- actually floating -- conductor and other hots. Meter designers work to get the highest impedance they can, so the meter doesn't load the circuit under test and change the voltage you're trying to measure. That's what you want in troubleshooting electronics. But for power systems, you really want low impedance. Try strapping a 15 watt incandescent light across your meter leads, and if the 6 volts goes away, then it was just capacitance. If it's still there, then it's the neutral being pulled away from ground by the current it's carrying and the resistance in it between where you're testing and the service entrance. I hope it's capacitance, because 6 volts out is a very crappy neutral. If you have a good ground handy, you can also measure between the neutral and ground, and between your dead line and ground.
>You can't use one common wire for two separate circuits. Otherwise you get the Phantom voltage.
Actually you can use one neutral for two circuits, provided that they're on opposite hots. The current carried by that neutral is the difference between the two hots. The trouble with that is that if somebody who doesn't know about it re-arranges things in the panel, the two circuits can end up on the same hot, and the current in the neutral becomes the sum, not the difference. That can result in an overloaded neutral.
The problem with an old house is that many different people of various levels of competence have probably done lots of different things in lots of different places down through the years. Getting it all figured out and fixed up is a very good idea.
-- J.S.
JS makes some learned points.
I just got spooked on the common side due to the issues in my old house. Commons & ground wires in all of my circuits go back to the load center. I don't like the concept of sharing too much.
My house was built in 1910, it is amazingly structurally sound. Poured 12 inch basement walls helped. Electrically, I wasn't impressed.
I had a strange occurrence when cooking in the deep well of the stove that came with the place. Of course the pinto beans boiled over and shorted the element in the stove. What happened next ought to be a lesson for the people with old homes & wiring.
All of a sudden the refrigerator next to me cut out, The lights in the house started going brighter then out, the stereo sent out a sacrificial puff of smoke, and beyond that all that I could see was my wife and I tearing around the house unplugging all the appliances we could think of.
WTF was heard probably out of my mouth. Looking at the Fuse panel. (Yes, Buss plug type panel) there was nothing blown. The 30 A Buss plug fuses in the stove wasn't blown either. From there I was mystified. Pre load center there was a cast iron box with a 2 inch lever arm. Swinging that lever did nothing. It was tagged by the electric utility with one of those lead & wire seals. Somehow hooked into the box was a 6x6 pull box with a decal in red decrying a hotwater auto shutoff controlled by the utility. (at that time my hot water heater was gas). Everything pointed tword that cast iron box as being the culprit. But it had the Utility's seal.
I was at that time, out of my depth. ( I hope I learned something in 20 years) I called the Utility. They came out and I was greeted with the statement that Thomas Edison must have been on the installation crew for this setup. They popped the seal and showed me 3 fuses inside the CI box.The middle one was blown. Wait... 3 fuses? This is a home. 2 legs of 110, together 220v? OHhhh A fused neutral. No ground rod inside the house.
This lost ground yielded 220 volts at every outlet. Not damaging to the building wire cause it is all 300 to 600 volt rated. But Lightbulbs, all toast. The stereo and other appliances were hit or miss in terms of harm. Refrigerators have a klixon bimetal thermal device that protect them. The stove element was garbage anyway.
So with a new service I later became the ground police. Department of redundancy department for me. That goofy common wire can cause havoc if not big enough nor hooked the right place.
Near as I figure it was a factory electrical guy (notice I don't say electrician) that cobbled this mess together. Day one I figured the guy was different as all of the ceiling lights switched the common not the hot. Try replacing a broken bulb with that setup.
As long ago was stated, get the VOM and go room to room, outlet to outlet, switch to light. Clean up the mess and rest only when you know it is done right.
As a passing note, don't blame the fuse. Those never fail, it is when they are misapplied, as was this case, where the problems arise. Never fuse a GROUND
Good "lesson learned" history, had not know some old houses fused the neutral. My Grandma's house built in 1913 had pieces of solder between posts for fuses, but the neutral was solid.
One comment on "never" in the following - "..don't blame the fuse. Those never fail.."
Everything has a failure rate, for fuses it may be due to mfg defect, tin whiskers, fuse metal crystallization, etc. Specifications for many complex high reliability systems prohibit the use of fuses due to an unacceptable failure rate. The faiure rate is however low enough that a 50 yr old house with 10 fuses would likely not have a fuse failure per se.
Yes, Never is a big word.
Fun fact, I sell both Fuses and breakers in the industrial market to OEM's etc.
Those 1/4 by 1-1/4 glass fuses if wrapped with one thin layer of aluminum foil have a fuse rating of 1025 amps. The traditional "penny in a burned out fuse" has a rating of 2200 amps.
Frightening what grandpa used to do isn't it?
I remember a story from an FAA tech about a VORTAC station that kept going down every couple of months.
They checked everything it. Never found a problem. Would sit on it for days with any problems. Then a week later it would be donw again.
Every time that got there the same fuse was blown.
Happened to go to the station one day for require checks just as it happened to go down. Went to replace the fuse and the holder was hot.
It seems that the holder (clip in) was sprung just enough that it did not make solid contact. The connection would heat up and melt the fuse.
Size of the fuse causes some heating problems too.
Type CC fuses. Per the NEC you can rate them 300 percent above the load for certain amp & volt& load situations. (read the NEC before you do this)
The rule of the road is this. The bigger (in size) the fuse, the more heat it can dissapate.
All that happens in a fuse is a link melts when the amperage is too much. the link is a stamped piece of metal of certain gauge & cross section.
It is easier to sweat in a hot box than it is to sweat out in the wind. If you get nusance trips for a correctly sized amp fuse then consider putting in the same rating with a larger physical size fuse. (RK-1, or LPJ, size for the CC replacement would be examples) Make certain the voltage capability of the fuse is beyond the load. ie 600 volt rated fuse for a 480 volt load. NEVER PUT A 300 VOLT RATED FUSE ON A 480 VOLT LOAD. It may explode when it blows.
Sometimes the designer is ignorant of the load. Sometimes the fuse that replaces the original is what is handy rather than what is right. Load type determines the fuse, Transformer vs, HID lighting, VS incandecent lighting, vs a motor. All behave differently electrically. Consult a fuse catalog or manual or the guy behind the counter at the Electrical supply house.
Re: the 1910 house, think back to the days of K&T wiring when there really wasn't a polarity as we know it today. All wires were black. The fact that all of your lights switched the neutral tells me that someone at the start made the mistake, or there was a rewire (like my 1910 house had in 1949) where things got screwed up and reversed. That is why I have suggested people check the polarity of all the outlets on a circuit before reversing the hot and neutral in the box. You might just find that a different 50% of the devices are now reversed. Its the guys who are random in their habits that scare me. I don't believe anything in a pre-1950's house should be believed until tested. And in the case or receptacles, a visual inspection is called for too. Most of my grounded outlets had the neutral and ground connected at the device. When you see grounded receptacles but only 2-wire old romex at the panel, look further. ;-)
Re: not pulling another 12-2 when you had the chance, is the new wire stapled in place where it is hidden behind the wall? If not, you might consider using the recently installed wire to pull a couple of pair up if there is room, or locate another wire which is not stapled to use to pull a couple of runs. When we decided against central air and figured we could do it as easily with window units, we used a 14-2 that fed outlets in two bedrooms to pull up a couple of 12-2's that would each supply a room. I would not reuse wire that was used to pull other wire in a circuit since 30 ft of 14-2 is like a buck eighty, so why risk it. But it sure made it easy to get the 12-2 to where it was needed. Just think what it would have cost to drill holes and blind fish wires from the basement to the third floor. Now as a matter of habit I will often pull a piece of twine or rope with the wire so that I have an easy way to repull along the same path in the future if necessary, or even better, I'll pull a couple of runs in the first place. I'd bet there is about 300 ft of unused pulled wire in my house at the moment that is sitting there for future projects/repairs.* And the toal investment in that wire is less than $20. Compare that to the cost of having someone else come in to pull wire, or the time it would take you to pull it again. I also install the biggest J-boxes I can when possible. They are only 80 cents more and it is nice to have the room to install 4 circuits instead of 2. My redundant wire pulls are all sized to get me to an existing J-box with extra room at the far end. The extra $40 I have wrapped up in material is going to save lots of time down the road.
* In order to sort out who is who in all those unused pulls near the service panel, I connect the ground conductor of the run at the device end to a j-box, and then use my VOM to locate the romex whose ground conductor measures 0 resistance at the service panel. And yes, I test all of the wires to make sure there aren't two. ;-)
Ditto on using the biggest boxes, 4 11/16" square. I'm doing all new work at home in 3/4" EMT with compression fittings. That way you can always pull most anything you can think of.
-- J.S.
The reason I got this place back in 1981 is that the owner was the 2nd guy to own the place. The first was the architect. (I've got a sistered floor joist under the main floor that contradicts that title) He moved out after only 5 years. The owner was the nicest guy you ever met. The best thing was he did nothing to the place except clean it. (he was a janitor in the local school)
All the woodwork is original. w/o the latex paint on the nice old oak. Back-in-the-day when they used straight grained heartwood and no molding is less than 1" thick. The mop boards (baseboards) are 10" tall with a 1-3/4 cap on top of that. It was love at first sight. Nothing fancy and not trendy enough to be Craftsman style. I like to think of it as guy-with-big-screwdriver style. You ought to see the mantle. Not too thick to be gaudy, but thick enough to make you think about the tree that supplied it.
Spooky thought for me was that there was a cigar box of Knobs from the k&t in the basement when I moved in. Despite all my destruction of redundant doorways (I bet I took out 5) I never found evidence of K&T in this building. I've rung out every wire and frankly don't have a bad feeling about the BX. It would be a nightmare for a production guy but it sure takes the worry out of hanging pictures.
To finish this bungalow (yes this was an unfinished to be finished by owner building) I bet I put 500 Bd foot of Oak into the upstairs. Most wouldn't see the difference but If you live with it you can feel that it was close but I didn't hit enough antique stores to find the correct hardware. With kids antiquing everything every day it is only a matter of time till it looks the same.
Back to the wire. Yes extra wire and circuits are a blessing. It really helps when you realize you need a separate circuit for the washing machine.
Last strange thought on the original wiring was that every connection was made in a mechanical (not crimp) screw lug. wrapped with rubber then friction tape then Cambric wrap? I Sh.. you not, these were the most intense connections I ever saw. You'd think this was a medium voltage termination. Take a few of those apart and rewire the box and you feel like you are in Texas with wiring room. I went thru lots of shrink tubing to get to this point.
In almost all cases a new circuit breaker will solve this problem. These units don't last forever and the springs can get weak with age. We all make a bit more noise as we get older. While its out look closely at the bus bar for corrosion or arcing. Putting a new breaker on a damaged stab will shorten the life of the breaker.
A few beaker tips:
1) Once a year turn off all the breakers. This distributes the grease around the pivots and makes sure everything is still operable. While they are off I usually do a quick check with a wiggy. Some times I find one that fails closed.
2) While your in the breaker box and the main is off, double check to make sure the power is actually off at the main, make sure the lugs and bus screws are snug. This is a bigger issue with aluminum feeders as they can migrate away from a connection. Don't forget the ground and neutral bars. No need to prove your manhood on them. Just tight enough. If you want to get technical use a torque wrench. Most electricians do it by feel. Some would do better using the wrench.
3) Inspect the connections for heat damage or corrosion. If it is an aluminum connection go ahead and redo the connection. Be sure to wire brush the oxides off and then rebrush with oxide inhibitor. Taking the lug screw out and greasing its threads with the same goo can save problems later.
4) While your at it go around the house and test all the GFIs.
Thanks All,
a further update:
Fortunately I don't have to deal with aluminum.
I think I found the problem wire in one of my boxes - rubber had fallen off one of the neutrals - I'm going to try the shrink-wrap tubing trick to protect it and hopefully all will go well. Now I have to put all the outlets and switches back that I pulled trying to figure this thing out.
I'll pull the breaker if all doesn't go well and swap that next.
Amen on doing things in a mediocre way screwing things up - when I bought this house, several of the "junction boxes" consisted of two armored cable ends tied together with wire nuts hidden underneath some flaps of wallpaper. I've found all those (I think) and replaced them with true junction boxes. The problem is always, what do you fix and what do you leave alone.
I'm still kicking myself for not running another 12/2 romex to the attic when I had the walls open last year.
Thanks again,
Ben
The bad breaker does have some internal parts that are considered friable. Friable is a term used electrically the same way brake shoes are on your car. The electrical contacts on a breaker have only a specific life. With resistance circuits (lights) it is longer than with Inductive (motor) circuits. Motors have Inductance that is created by the magnetic nature of a motor. Quickly put, it is the desire not to turn off all at once. The motor spins and doesn't want to lose the electrical relationship so it pulls an arc on the contacts. Arc's or corona's aren't free. Those vaporized ions of metal are your breaker contacts in that light show. Breakers have an arc chute that contains and supress the arc. Suppression or not that arcing of an inductive load makes the breaker contacts pitted. Pitted contacts are bad conductors. bad conductors cause resistance (heating) and greater load on the breaker. The breaker is at the switch point when it buzzes. There isn't any fix except replacement.
This supression is the AIC discussion held in a different thread of this area of Energy Heating etc. of Breaktime.
Motors and inductive loads eat up the breakers. Lighting circuits don't. (Unless you are talking about the first 10 milliseconds of a lightbulb circuit. That is another electrical anomoly that only relates to solid state relays.)
Ben,
Trying to salvage that line is a bad idea. You not only risk "blowing" more breakers but also damage to appliances and fire. Do yourself a favor. Disconnect all of that old BX garbage from the breaker box, pull it out of the walls or cut it off and leave it in place. Then buy some Romex and run it to the old boxes for outlets, switches etc. and back to a new breaker. Split up as many outlets and switches as you can; the fridge should be on its own 20A #12 line. I don't know if you have a QO laod center or what because you didn't mention it but, it is an extremely simple operation to run new cable. There is no major drywall work involved. You will be alot happier with new ectrical work. I worked for an electrician for a while. When we came across this situation many times we did not hesitate to pull all of that BX #### out of the walls. I know what that old wiring looks like, taped and tarred connections, frayed ends, etc.. It is dangerous and at the end of its useful life.
I hope I was helpful.
Thanks Henry for the advice;
The circuit does have several outlets on it and a whole bunch of lights, but that's all. No "dedicated," appliances - the fridge, washing machine, dishwasher are all on dedicated new circuits. I will think twice before plugging in the A/C unit into that circuit. I will think about ripping out the circuit - I know that's the right way to do it. The circuit is properly grounded (I checked) and all the really poor work that was done I did repair. Unfortunately my wire-fishing skills are a bit subpar - unless I get better, I'm going to have to repair some wall damage. Let me get through redoing the Living Room (another mess, electrically and otherwise) before I tackle this extensive circuit. I have another year before I need the A/C again! Like I said before, I'm kicking myself for not running a spare 12/2 line to the attic when I redid the bathroom and had the walls open for the plumber.
Thanks everyone for the advice,
Ben