Ceiling Fan vs. Insane Electricians

Discussion in 'The Projects Forum' started by m4yh3m, Feb 13, 2008.

  1. m4yh3m

    Thread Starter Senior Member

    Apr 28, 2004
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    So I bought a ceiling fan to install in an apartment bedroom. I took down the light fixture and low-n-behold.... someone installed wiring that conforms to the "i don't give a damn about standards" standard. 1 exposed ground, 2 black coated wires. Just out of curiosity... I turned off the light switch and tested the cables. Black to black generated around 4 volts. Black #1 to ground generated 232 mV, and Black #2 to ground generated around 4 volts. I decided to flip the breaker to the room to ensure safety. After getting ceiling crumbs in my eyes, cutting my hand, swearing, having to go buy extra anchor screws since there were some missing, buying a new drill to show those screws who's boss, and somehow managing to get a small shock from the wiring even though the breaker was off, I finally had my new ceiling fan working. I'm still wondering/worried -- how do I know if I connected the wires properly? How can I tell which wire is hot?

    And if need be...what kind of paint-like substance can i put on the wires to make sure they're not exposed anywhere they shouldn't be?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    With the breaker OFF, between the ground wire and the neutral wire would measure very low resistance, and the hot wire (either L1 or L2) would measure as open to either ground or neutral. Ground and neutral are connected together at one place only; the bus inside the breaker panel.

    When you measured voltages with the switch off, it was probably due to voltage drops in the wiring of the circuit while having a fairly heavy load(s) on the circuit at the same time, like an electric room heater and halogen lamp, and wires running parallel inductively coupling current for the open hot circuit.

    Heavy current would cause voltage drops across both the neutral and hot wires.

    It's hard to tell for certain which wire was hot, and which one was neutral from the tests you did and the information you presented, but if you know what other loads were being powered by that breaker at the time, you could make a reasonably good guess.

    14 gauge copper wire has a resistance of 0.001485 Ohms per foot. Let's assume for the moment that your 15 Ampere circuits are wired with 14 gauge copper wire.

    I'm just going to suppose that you had a couple of 60 Watt bulbs lit, and a 10w clock radio plugged in, for a total of 130W power being used. So, let's figure the current:
    I = P/E
    I = 130/110
    I = 1.182 Amperes
    I'm going to guess that your circuit breaker panel has 40 feet of wiring between itself and where those items were plugged in.
    40 * 0.001485 = 0.0594 Ohms
    That's the resistance of the neutral wire. Let's see what happens when we put current through it:
    E = I x R
    E = 70.2 mV (approx)
    Well, you measured 232mV instead of 70.2mV.
    Perhaps you were running 360 Watts worth of appliances at the time?
     
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Ideally, there should be no hot wire in the box for the ceiling fan. There should be a switched hot lead from the wall switch. This switched hot lead should read roughly zero volts to ground with the switch off and roughly 120 or 240 to ground with the switch on. (Depends on which nation your apartment is in.) The wires would have to be measured with the breaker and switch both on to determine which was hot. Exercise extreme caution.

    If you are in the US, the box supporting the fan needs to be rated for a dynamic load in excess of the fan. A regular old box for lights isn't good enough to please the inspectors. (NFPA-70 314.27(D))
     
  4. m4yh3m

    Thread Starter Senior Member

    Apr 28, 2004
    186
    42
    Thanks a bunch for the info!

    thinkmager3: Eh.... Georgia inspectors don't really give a damn about doing the job properly :p We've probably got some of the laziest in the country. What gets me is these electricians are THAT lazy that they can't use color schemed wiring. Friend of mine had a house that was built in the 70s that had colored wires running from the switch to the ceiling box when I put their fan in. This is a fairly new apartment complex. I can't believe they're still getting away with some of the things they do!
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    Funny how building inspectors always sign off on cruddy work like that - and if you ask, they were just by yesterday.
     
  6. m4yh3m

    Thread Starter Senior Member

    Apr 28, 2004
    186
    42
    just a quick follow up for anyone interested... the piece that connects the fan blade to the motor was bent badly on that fan causing it to shake violently, so i took the whole thing down and returned it then went to a different store and bought a different brand. Before I connected the wiring I inspected it a little closer. Parts of the insulation seemed to have "dried out" and fell off, so I taped portions of them up. Still freaks me out how bad this stuff is... but I eventually got my fan up and running. Much nicer than the old one :p
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    I am NOT an electrician!

    But it sounds to me like someone used bulb(s) that had a much higher wattage than the original fixture was rated for, which cooked the wiring's insulation. This has led to an unsafe condition, and is probably not the fault of the original electrician, but the fault of an uninformed person using an incorrect bulb or bulbs.

    Many ceiling fixtures are rated for 60W bulbs, but I've found 100W bulbs in some of them. :eek: It was this exact scenario that caused a fire in the basement of a 112 year old church in my hometown, causing it to be levelled :(

    I suggest that using "electrical tape" or other kinds of tape to patch the insulation is not a good way to repair the damage. You should notify your landlord that you need an electrician to come and repair it properly. In the meantime, I suggest that you leave the fan off.
     
  8. m4yh3m

    Thread Starter Senior Member

    Apr 28, 2004
    186
    42
    The fixture in the room was a simple overhead light. I installed a fan because its gets so freakin hot in here. I'm going to get the LL to come up and see what's going on. The intelligent people that built this complex also hooked the bedroom up with the bathroom that's running 220W worth of lights and the ceiling fan + any additional accessories that might need to be used (hair dryer, etc.).
     
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