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    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #1

    Dec 7, 2007, 01:58 PM
    Armored cable carry two sets of wire for two circuits?
    Strange question. I opened up my fuse panel box to see which fuse was for what circuits as its really old and although it was labeled, it wasn't completely labeled. Fuse 1 and fuse 3 hots, go into the same armored cable it seems. And this isn't the neutral either, as the neutrals go to a bus bar. So there is 4 wires. The armored cable then goes to a junction box. And out of the junction box another armored cable goes to an outlet in the basement, romex goes out into the back porch which runs an outlet there, and another armored cable goes out of the house and from what I can tell must go to the garage. As it disappears into the ground and then armored cable comes out of the ground into the garage. Plus the panel says that fuse 3 is garage. When I unscrew fuse 1 the outlet in the basement and porch stops supplying power. When I unscrew fuse 3, those outlets are still hot. But here is my problem.

    Wired into the fuse panel is a switch that turns on and off the garage outlet. The hots are marreted together, from the armored cable to the marret to the switch and to the fuse 3 hot. The outlet in the garage doesn't work period. I am not sure if this is related to the switch or the actual outlet. The fuse has been replaced so that takes that out of the question.

    So my questions are, can armored cable carry wires for two separate circuits? In regards to thee garage, which is the likely suspect that isn't working and what is the best method for checking without getting electrocuted. I test the outlet, but no power. I want to test the switch or power from the actual cable in the garage that the outlet is connected to safely. Or is this so called "two circuits per armored cable" business the problem?
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #2

    Dec 7, 2007, 04:15 PM
    You can have a red and black share a white , if on opposite phases.
    Also between fuse 1 and 3 you could get 240 Volts. Maybe switchleg(s) were run later, and separately.
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #3

    Dec 7, 2007, 04:23 PM
    You could be right about a shared neutral. I don't have the panel off anymore and can't remember. But otherwise, I don't really understand the rest you mentioned. They can't be 240 because from the junction there is two outlets, both 120, and then the one in the garage which doesn't work, is also a normal 120 outlet.
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #4

    Dec 7, 2007, 04:54 PM
    I was thinking 2 hots, no neutral, likely 240 volts. The fuses are 2 120 volt circuits on opposite phases.
    Opposite phase is the other hot. If you have a #12 neutral shared with a black and a red.
    If on same phase neutral could see up to 40 amps. Where if on opposite phases, neutral would carry the difference of the 2 loads. If one was drawing 15 amps and the other was drawing 14 amps. Neutral would draw 1 Amp.
    Multicircuits MUST be on opposite phases.
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #5

    Dec 7, 2007, 06:37 PM
    Sorry for my ignorance, but I still don't really know what you mean really. I think I kind of do? Now that you mention it, one of the hots is red. But again, they are running two separate 120 circuits. I believe that the armored cable is #12. I can't really tell, but the romex coming out of the junction box is labeled #12. Plus the outlet in the basement has a 20 amp outlet in it (not that that is the way to tell). So should this be wired this way? Shouldn't fuse 3 just have its own wire coming out to power the garage? And would this explain why the outlet in the garage isn't working?
    Cobraguy's Avatar
    Cobraguy Posts: 140, Reputation: 11
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    #6

    Dec 8, 2007, 06:26 AM
    Let me see if I can help you understand Stratmando...

    If you have a multiwire circuit sharing a neutral, the 2 hots must be in opposite phase. This means that they must be on opposite buss bars in the main panel. If they are on the same bar, then the neutral sees the sum of the amps on each circuit. In this case, 40A would be possible which would melt the neutral. When they are on opposite bars, they see the difference between the two circuits. This means the neutral would see a maximum of 20A... which a # 12 wire is rated for. You need to make good and sure you have a multiwire circuit properly wired as the neutral is not overload protected. In fact, I think you'll soon see that all multiwire circuits will be required to have the breakers tied together. This will ensure that the circuits are on opposite phases and that someone who doesn't recognize a multiwire circuit doesn't just shut off one of the two breakers and go work on a fixture and get bit.
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #7

    Dec 8, 2007, 07:51 AM
    Hey Cobra, Hope all is well, Before GFI's in Kitchens, In some Kitchens, I used to have a multicircuit going to same recepticle(Break the hot tab). You could not trip a Kitchen Breaker. Breakers would need to be tied in those instances.
    I think you may be right on future tying of multicircuits.
    I am amazed how long it took for Dryers and Ranges to go to 4 Wire.
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #8

    Dec 8, 2007, 06:57 PM
    I still don't really know what you guys mean, and whether it applies to my situation and garage outlet not working problem? Or whether I should be concerned and have an electrician rewire it. How can I tell inside my panel what to look for?
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #9

    Dec 8, 2007, 07:15 PM
    I think when you said fuse 1 and 3 , we were thinking 2 120 Volt circuits or 1 240 volt circuit.
    Since 120 and 2 circuits, was thinking at least a white, red and black. A switched outlet would be another conductor, making it 4 conductors, not counting ground. 3 conductors if 1circuit, a neutral and 1 switched outlet.
    What are all the wires going out to garage?
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #10

    Dec 8, 2007, 08:56 PM
    Well I opened the junction box to take a look, but it is tight in there (older box, so I suppose size wasn't as important, or the person who put it in didn't use the right size) and since it was so tight I didn't want to mess around. So really, I'm not sure what wires are going out there. Also, when I say fuse 1 and 3, they aren't actually labeled that specifically, I gave them those numbers. There are four fuses in the box, two on top and two on the bottom, and I numbered them left to right, top to bottom. Or clockwise it would be 1, 2, 4, 3 if that makes sense. So 1 and 3 are beside each other with 1 on top etc. I don't know if that matters at all.

    Also, there is a switch wired into the panel that goes to a wall in the stairs that says garage on/off switch. And when you look at it in the panel, its wired into the 3rd fuse (rather pigtailed etc.). I bought the house from my brother and he changed nothing while living here, but he did say that the garage outlet worked for him. It never has for me. Maybe its me:) I don't think so though.

    So I guess, does this info help? And should I use electrical probes to test the switch and outlet to see which is the culprit? And why would this be wired this way, as opposed to just wiring the two circuits separate? They aren't really related. I have a 20 amp fuse in number 1 and a 15 amp fuse in 3. I don't know if this is right or safe either. And also, thanks for all your help!
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #11

    Dec 8, 2007, 09:04 PM
    And just to add some more (I forgot to mention this) I've been researching this subject, and I've read this thing about splitting a receptacle. It says that some codes require outlets to either be split or alternating. I don't really understand the differences, and why code would mandate this set up, when you can easily run a different circuit for each outlet etc. The reason it states to do this (in the book I have) is because hi amp devices can overload a circuit. But why wouldn't you put in a 20 amp circuit in that case with #12, or like I mentioned above different 15 amp circuits for each outlet if the device is hi amp like a heater or something? I know I asked a lot of questions in two posts!
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #12

    Dec 9, 2007, 07:30 AM
    I always use #12 on a 20 amp. Not sure what you mean "split or alternating"?
    If each 15 receptacle had its own breaker, the panel would fill up fast.
    With 20 Amp circuits. A heater won't usually trip the circuit.
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #13

    Dec 9, 2007, 09:24 AM
    What I read mentioned three conductors plus groud, going from a double pole breaker to one outlet with the tab broken off, with black hot to the top outlet and the red hot going to the bottom part of the outlet. They mention you might want to do this if there is going to be two high amp devices on one outlet. That makes sense to me. Alternating, they show again 3 conductors plus ground, where the black hot connects to outlet 1, and the reds continue, and then the red connects to outlet two with the black continuing, and so on. Which makes me think that this might be my situation? But in that case, other than to save on running wire (and since there are two fuses anyway for both circuits) I don't really see the point. But I suppose it might make sense to run one wire instead of two to save time and money. But in my case, its maybe an 8 foot run from the panel to the junction, and then it's individual wires from there on out. So to save time and money on wire doesn't make much sense to me. Plus it mentions that because it is a double pole breaker when you shut off one circuit, they both shut off (or trip etc). But in my case I can pull out the third fuse and power is still supplied to the outlets in the porch and basement. I can't test for the fist fuse because I have no power in the garage at all right now.
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #14

    Dec 10, 2007, 07:33 AM
    Pulling separate neutral is OK. Then they don't have to be on opposite phase.
    Test power out of all fuses, then in and out of switch.
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #15

    Dec 10, 2007, 07:47 AM
    How do you test the power at the fuse? I know how to test at the switch and outlet, but not sure at the fuse. Do I just probe the internal threads, and the contact point in the middle? Thanks again.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #16

    Dec 10, 2007, 08:02 AM
    Remember that in the main panel white and bare are tied to the same bar and that bar is tied to the ground of the box. I'l call these G (bare) and N (white)

    240 has two hot legs, 180 degress out of phase with each other. I'll call these L1 and L2.

    Between L1 and L2 there should be 240 V.

    Between L1 and (G/N) there is 120 V. Between l2 and (G/N) there is 120 V.

    Between G and N there is ~ 0V.

    The background out of the way.

    Usually one set of fuses get power from L1 and the other from L2.

    You should check for power at the load terminal of the fuse.. If that's not present, remove the fuse and check for power at the center tab of the screw base. The power test at the box is respect to ground/neutral.

    They are at the same potential at the box. Neutral carries return currents and ground carries fault currents.
    ceilingfanrepair's Avatar
    ceilingfanrepair Posts: 5,733, Reputation: 109
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    #17

    Dec 10, 2007, 11:01 AM
    Quote Originally Posted by KingsX
    Strange question. I opened up my fuse panel box to see which fuse was for what circuits as its really old and although it was labeled, it wasn't completely labeled. Fuse 1 and fuse 3 hots, go into the same armored cable it seems. And this isn't the neutral either, as the neutrals go to a bus bar. So there is 4 wires. The armored cable then goes to a junction box. And out of the junction box another armored cable goes to an outlet in the basement, romex goes out into the back porch which runs an outlet there, and another armored cable goes out of the house and from what I can tell must go to the garage. As it disappears into the ground and then armored cable comes out of the ground into the garage. Plus the panel says that fuse 3 is garage. When I unscrew fuse 1 the outlet in the basement and porch stops supplying power. When I unscrew fuse 3, those outlets are still hot. But here is my problem.

    Wired into the fuse panel is a switch that turns on and off the garage outlet. The hots are marreted together, from the armored cable to the marret to the switch and to the fuse 3 hot. The outlet in the garage doesn't work period. I am not sure if this is related to the switch or the actual outlet. The fuse has been replaced so that takes that out of the question.

    So my questions are, can armored cable carry wires for two separate circuits? In regards to thee garage, which is the likely suspect that isn't working and what is the best method for checking without getting electrocuted. I test the outlet, but no power. I want to test the switch or power from the actual cable in the garage that the outlet is connected to safely. Or is this so called "two circuits per armored cable" business the problem?
    Reading the original question, I can't quite see how this thread got so complicated.

    In my parents house, all of the circuits that are original to the house are wired on 3-wire BX cable. Each armored cable has three wires, black red and white. Each cable ran to a section of the house (two bedrooms, the living room and kitchen lights, two sets of kitchen outlets, etc) so that two circuits would share the cable and the neutral. Each set of circuits was wired on opposite phases. This house went up in the 1950s, originally had fuses, then had Federal Pacific breakers, now there's some other breaker box.

    It sounds like your armored cable has four wires rather than three-- two hots and two neutrals. This is fine.

    The way I understand it, one of the hots goes directly from the fuse to the armored cable, the other goes through a switch and then to an armored cable? Am I correct?

    Do you have a voltmeter? If so, measure between the hot lead and ground and several places along the circuit and find out where it drops out. From right off the fuse to ground should read 120. After the switch to ground should read 120. At the junction box where it splits off to the ground should read 120. Etc. if you get all the way to the outlet and you still have a problem, the open may be in the neutral rather than the hot, in which case you trace that back.

    Get back to me on how many neutrals you have, if it's only one you can measure across the two fuses to confirm that everything's cool with that. We'll explain later.

    And wires that are stamped with the number 14 require 15 amp fuses. Wires that are stamped with the number 12 require 20 amp fuses. See if you can make out anything.
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #18

    Dec 10, 2007, 07:53 PM
    Okay, I opened the panel again to take a closer look.

    Just to lay some visual, at the top of the fuse box, the armored cable comes in that we've been speaking about. It comes from the junction box that feeds the outlets in the porch and the basement, and the outlet in the garage.

    Coming into the side of the fuse box, is the cable from the switch that is located on the wall in the stair well.

    There is only 3 wires in the armored cable. None of them seem to be ground (I assume the armor is ground)

    The black wire from the armored cable goes to fuse 1 hot.
    The white wire from the armored cable goes to neutral bus bar.
    The red wire from the armored cable goes to a nut that joins it with the black wire from the switch cable coming into the side of the box.

    Therefore,
    The black wire from the cable from the switch is "pigtailed" to the red wire from the armored cable. (same as what I just wrote above just reversed)
    The white wire from the switch cable goes to fuse 3 hot.
    And there is no ground wire from the switch.

    And I can't tell what is going on in the junction box, as it is too tight to tell.

    I hope this helps?
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #19

    Dec 10, 2007, 09:31 PM
    Armour is ground.

    So, does this mean you have two hots feeding the garage outlet?

    With the switch on. Measure from the wide blade of the outlet to ground and the narrow blade of the outlet and ground and report back.
    KingsX's Avatar
    KingsX Posts: 231, Reputation: 10
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    #20

    Dec 10, 2007, 10:00 PM
    Before I do that, this might be something important or not, I'm not sure. The lone outlet in the basement had an outlet in it that is pretty old and everything I plugged into it would slowly fall out. So I decided to put in a new outlet. So I did last night. But, the old one was wired backwards. Being that the white was connected to the brass, or narrow side, and the black wire was connected to the steel or wide side. Which is backwards. So thinking that maybe someone before wired it backwards at the junction, I decided to match what was there (should have tested first). After I was done, I put the black probe on the screw and tested for hot. And sure enough, the wide side was hot. Which is wrong, from what I know. So I opened it again and rewired it right. And tested again, and now it seems right.

    But would this have anything to do with everything else we're talking about, or did someone just connect this outlet wrong and its all good now?

    In regards to checking which is hot, do you mean at the switch? At the switch, there is not ground. The wire coming from it is black (unknown to me age) with only two wires in it. The switch is a museum piece as well. Should I just test for current at the switch instead? Or did you mean the outlet in the garage? Sorry for the confusion...

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