The "Carter System" Again.

mickeyco

I may owe someone a beer (or a pot stick with all the talk going on in the politics forum). Early last evening I received a call from an old school buddy (electrical engineer) needing a little help with some 3-way switches he was replacing in his apartment building in the Rogers Park area of Chicago. He was replacing the original switches that were brown to white after remodeling the common hallway and was having problems. Seemed easy enough, I've seen people mix up the wires and have problems before, not an electrical engineer though, and I wanted to get out of the house.

The apartment building is a 4 flat originally built by the Government (this may explain the cheap wiring) in the early 40's for sale to veterans returning home from the war. There are tons of them in the area and close by suburbs (I have one of them). The electric if untouched is cloth wire in metal conduit and fuses, although a lot of them have been upgraded to circuit breakers.

I go out there with just a meter, strippers, wire markers, flashlight, a long piece of wire and a screwdriver thinking it will be a ten-minute job and then some reminiscing about old times and back home. I figure out that everything in the hallway, the 2 outlets, and 5 lights (one exterior) are on a single circuit and turn it off. Then I start isolating the wires by continuity (couldn't tell the color of the wires, old cloth, they all looked the same) using my long piece of wire, get that done and it doesn't make sense, there are not enough wires. I started thinking about the recently covered topic and lesson on the "Carter System" on the board, but the house is from '40s, maybe an old electrician from the '30's using some fancy tricks? Didn't really know because my buddy had all the switches removed and didn't mark the wires. I asked him if he knew the neighbors (identical building) and if maybe they would let me pull a bulb and check, we went next door and the neighbor said sure no problem. I put one end of my wire to the ground lug on the outlet and the other to the meter. Then the other meter lead to the threaded part of the light socket and had my friend switch both switches, BAMM, the polarity is reversing, ie. the "Carter System", 2 of them in the front hallway and two of them in the back hallway, and I'd bet a few inside, same at the neighbors house on the other side. I marked the wires for my buddy and gave him the diagram (printed off CT) and let him hook the switches up and recommended pulling new wires. I'd bet that most if not all of these buildings, and there's a lot of them in the area all have this, I wonder if it was the electrician or to save money. The timing of this blew my mind, what are the odds, I should probably be buying lottery tickets. Thanks to mdshunk, RobertWilber and Speer007, although Speer007 didn't really do anything besides post the question, but without it, no answers, anyhow it saved me what I guessing would have been a lot aggravation and wasted time.

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Some people climb mountains. I take out the trash. But we both do it for the same reason.

mdshunk

I'm surprised to hear that in an electrically progressive city, such as Chicago is. Glad you were able to troubleshoot that so quickly. I'm sure you impressed your old pal. If he's an engineer, he was probably tickled to learn about the Carter system. Since he's all pipe in that place, I think he'd be nuts to not pull some new stuff before long and get that squared away.

747

Thats a great part of chicago to own a apartment complex in .He should have NO problem renting them. Alot of University students live in rogers park and lakeview.

JamesNLA

Glad you got that worked out, but I wanna know about your graphic!!! How or what program did you make that in?? If you photo shopped it, I'm guessing about 40 layers!

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"....And then we all switch places when I ring the bell"
-Adrock

mickeyco

I hope our kidding about Chicago being progressive, they're on their own electric code, and getting a permit is a royal pain in the a$$, so very few get them for small jobs (lots of bad, unlicensed work out here). I recently worked in a new home under construction in the city and all the guys doing the electric were laborers from god knows where, but they had a "licensed supervisor", I never saw him. The whole State is a mess every town has adopted their own code, usually a version of the NEC but quite a few have no electric code at all. Where I'm at we're '99 NEC but a block down it's '05 NEC, the unincorporated nearby areas are on the county code which is '02 NEC (this is within a 2 mile radius), same thing with the building codes, and every one of them have local amendments, it's a mess, you need have every code-book made. I'm hoping for State-wide codes.


The whole thing was kind of wasted on him, in school he was one of those guys that did great on tests but couldn't do a thing in the labs without help. I remember him having a problem with the neutrals on a GFCI years back. I was more exited about figuring it out than he was, all he wanted was working lights. I probably would have pulled new wire if I had brought it but I wasn't expecting what I found. I had him hook them up because, even though I strongly recommended he change it in the near future, I doubt he will.



I used Macromedia Flash, the picture was a vector (could blow up as big as a house with no quality loss) converted to raster for posting, no layers, and real fast, a few minutes (no exaggeration) to make that one (not that it's too good), I already had the switch drawn. Macromedia (now Adobe) makes a few vector drawing programs that are real good for quick illustrations and you can find older versions cheap on eBay. I've been looking for a free one to recommend on the board but haven't found one for vector. Second Look (member here) told me about Inkscape (www.inkscape.org), a free vector editor but I haven't tried it. I finally tried Gimp (www.gimp.org) and that is an awesome free program that is similar to PhotoShop and would be great for these types of drawings.

__________________
Some people climb mountains. I take out the trash. But we both do it for the same reason.

jbelectric777

mick, another thing too add on the "carter system" is that the switching circuit is not always on the same circuit. And in that case when you do get the 3 ways wired right ya gotta make sure that both circuits are on the same phase or the fixtures bulbs will pop because they see 240V across that lamp.....

__________________
" For all those whom beleive in Telekinesis, Raise my Right Arm"

George R

HA! I may owe someone a beer too. I came across a Carter system today.

Long story short, my niece just bought a house built in the 20's or 30's (Central Illinois). The whole family went over to fix-up a few things before she moved in. I do remodeling and proceeded to do some plumbing repairs, a bunch of others started painting. My brother is an industrial electrician/instructor (that yellow tractor company) and was told that the 3-way switches in the kitchen were acting "funny." No problem he thought, he'd just check the system out, maybe change out the 70 yr old switches and be done in a few minutes.

The rest is virtually a repeat of the mickeyco story. About an hour later, he's still scratching his head saying none of the meter readings are making any sense. He had checked continuity of the wires and the voltage of different combinations. Again no color on wires, no visible markings on 70 yr old switches etc

By this time, I'm done with the plumbing work I'm doing, and he starts to explain to me what he's got to deal with, and how nothing makes sense. He repeats all the continuity tests, voltage readings etc so that I understand the problem. I'm confused as well.

However, I casually browse this forum and I had vaguely remembered reading something about a weird 3-way switch configuration and something about its use in Chicago, but I didn't remember any details, nor did I care to at the time. Just one of those little tidbits you store in the back of your brain.

Basically we were out of ideas, so we drive to my house, jump on the internet and find this thread as well as the diagram posted by jbelectric777 on 6/12/07 (forum won't allow me to post the link)


Sure enough, we go back to my nieces house, "meter out" the wires again (now with a diagram in hand) and suddenly everything made sense.

So currently the house is wired the same way it has been for the last 70+ years (in a currently illegal manner) but they now have functioning kitchen lights. Two new switches of course.

My brother can't wait to share the wiring diagram with some of his electrical brethren come Monday morning, and see if anyone else has ever come across a "Carter system".

Amazing. This thread saved us hours (if not days) of scratching our heads. Thanks to all.

Hey mickey, I'm with you. I'm buying a lottery ticket tomorrow.