Any Electricians in the house?

Discussion in 'Off Topic [BG]' started by Chunk-O-Funk, Jun 29, 2008.

  1. Just went to hook up a ceiling fan, something I've done many times before. What I have is an older house with only two wires, no third ground. Pretty typical for an older house, except this time both wires are black. How do I tell which is hot and which is neutral?

    Now, I know if it was a typical lamp fixture or even a ceiling fan with the chain pull controls it wouldn't matter, but I will be hooking up a Lutron single pole wall switch to control the fan speeds and also dim the lights.

    This wall switch comes with a module that gets wired to the fan. The module has a wire for hot, neutral, and then the two wires that control the lamp and fan. It's my assumption that reversing hot and neutral on this module would not be a good idea. I could be wrong though, and it may work just like any two wire lamp fixture. I just don't want to fry it to find out.

    Thanks for any help.
  2. Get one of those tools that you stick on it and it tells you the voltage/wattage, the hot one is higher (I think). Sorry I forget what they are called. That is weird that they are both black, I have never seen that, even on an older house.

  3. Curtybob


    Jun 2, 2007
    Jackson, MO
    Usually, digital multimeters will let you know by indicating a "-" if you have the probes on the reversed wires. So, if it reads voltage with no -, you have the positive lead to your house's positive wire.
  4. Curtybob


    Jun 2, 2007
    Jackson, MO
    Oh, and you are right about those control units. Don't hook them up backwards, and make sure you get the fan set up on the "high" setting, then lose the chain so that nobody can mess with it. It'll kill it up that way, as well.
  5. Multimeter, huh. Wish I knew where mine was. :crying:
    Even if I had it I'm sure it would need a battery which is one of those round lithium types. Ahh, crap.

    I should be able to borrow one tomorrow from one of auto techs I work with.

    Just so I get you straight.
    If I have the positive terminal of the multimeter on the neutral wire I should get a "-" reading, right?

  6. JimK


    Dec 12, 1999
    That works great for a DC Voltage.
    I'm assuming Chunk-O is talking 120VAC.
  7. Curtybob


    Jun 2, 2007
    Jackson, MO
    Yep... although I had a cheap radio shack special that didn't read negative. But if it's good enough for a professional to keep in the toolbox, chances are that it's at least decent.
  8. Curtybob


    Jun 2, 2007
    Jackson, MO
    Holy cow.... thanks for the correction, JimK. Been working on a circuitboard all day and had DC stuff on the brain.

    I guess the best way it to test each lead to a known ground and see if you get voltage.
  9. :eek:
    Yeah, it's 120v.
    Never seen a DC ceiling fan. :D

    Okay, I do have a small 120v test light.
    If I hook one wire to the hot and a good ground it should light up.
    If I do the same to the neutral I should get nothing.

  10. Freddels

    Freddels Musical Anarchist

    Apr 7, 2005
    Sutton, MA
    You could do what I do . . . I just don't turn the power off to those wires I'm working on. The one that bites is the hot. :D

    It's only 110. :)
  11. Tingles, don't it. :D
  12. Curtybob


    Jun 2, 2007
    Jackson, MO
    Yeah, sorry about that. I popped some capacitors on my trusty old motherboard last weekend, and I just got it fired back up this afternoon. I've been using my multimeter on the DC settings to double check my work, and just had the DC settings in my mind..... even though I knew that the house wiring was 120VAC. :rollno:

    Your test light will do the trick.
  13. +1 You need a "voltage detector screwdriver" like this one:
    Handheld Voltage Detector

    Touch it to each wire. Only the hot wire will make it light up.
  14. My friend and I were installing a ceiling fan in our fraternity house the other day. I believe he used something called a "Wiggy", but I'm sure thats not the scientific name for it.

    Funny story though. This house was built in the 1890's and has a bunch of circuit breaker boxes in addition to switch gears, many of which aren't labeled. Instead of doing trial and error, he connected some of the wires to his screwdriver, causing a shower of sparks. This tripped the appropriate breaker and saved us a good deal of time.
  15. Curtybob


    Jun 2, 2007
    Jackson, MO
    I've done that as well, but I just can't give advice like that. ;) Of course, wrong advice on a multimeter? I can do that. :hyper:

    :D :p
  16. Thanks for the help everybody!

    Hey Curtybob, fahgettaboudit!
    I'm have a feeling you've forgotten more about electronics than I'll ever know. :)

    I finely picked up a voltage tester like this one:

    I have another question.
    Of course the tester works and it lets me know when I got the hot wire, but only when the switch is turned on. I thought the hot wire was supposed to be live even with the switch off. :confused: Does this mean it's wired backwards as far as the neutral or hot being at the switch? Or do I have it backwards?

    Also, as far as wiring up the fan, I suppose it doesn't matter as long as I am feed the hot wire to the black wire on the module for the new wall switch. Let me know if I'm wrong there. I probably won't tackle it till tomorrow.

    Oh yeah, one more question, if you don't mind.

    I tried using this tester in a couple wall outlets just for the heck of it. I had an actual electrician come in and add a couple new outlets in my living room. When testing those the tester seems to work as it should. I can plug it in tell which is the hot terminal. When I do the same thing to any of the other outlets in my old house the tester lights up before I even get the tester to the terminals on the wall. This doesn't sound right to me. Is it?

    Thanks again!
  17. Curtybob


    Jun 2, 2007
    Jackson, MO
    Well, I've picked up so much junk in my pea-sized brain, that I'm lucky to recall my name half of the time. :p

    But yes.... hot to black.

    And for the old outlets vs. new outlets/ tester issue, I get the same problem alot. I haven't ever figured out whether the problem is in the construction of the outlets, the grounding of the outlets, or the way some electricians like to use the holes in the back for the connection vs. the screw terminal lugs on the side of the outlets.

  18. Thanks again.

    I guess the main thing I was concerned about is how it's wired. The fact that the hot is not always on shouldn't cause any problems, right?

    I *thought* the hot should be live with the switch in the on or off position. Is this a correct assumption?
  19. Curtybob


    Jun 2, 2007
    Jackson, MO
    Without looking it up in the wiring code, I can tell you that I've seen alot of it both ways. I prefer it to be switched on the hot, because I can work on the fixture without messing with the breaker box/fuse panel.

    For your particular fan/light controller, double check whatever installation documentation is there for mention of stuff like, MAKE SURE THE HOT IS CONSTANT/ NEUTRAL SWITCHED. If there is no mention (I'm gonna bet there isn't), you are in good shape. ;)