Radon Fan Installation

Discussion in 'Electrical Forum discussion & Blog' started by The old college try, Aug 31, 2008.

  1. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    I have a question about mixing wire size. I'm installing a radon fan and need to tap into an existing circuit to supply power to the fan. There is a light extremely close to where I need power, so I'm considering tapping at that location. The breaker is 15A, however, much of the cable on that circuit is 12gauge (there is old knob and tube wiring at some points in the ceiling at various locations). Here is my question. I have 10 feet of 14/2 laying around and would like to use that rather than paying a premium for 12/2. I know that it could cause problems in the future if someone decides to randomly change the circuit to 20A, but will I break any codes by using the 14/2? Seems stupid to even ask the question over 10 feet of cable, but if you've been to the hardware store lately, cable is darn expensive. I should also mention that the existing wiring in this house is a complete abortion thanks to each previous owner screwing things up a little at a time... crap.. I just made myself think i should just go buy a chunk of 12/2. I hate when I do that.
    Last edited: Aug 31, 2008
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I will let bobnh or another of our professional electricians address the specific issue of the codes on this.

    I would make 2 comments..

    1) you mentioned tapping off a light.....this sounds like a source controlled by a switch, and I assume the radon fan should run 24/7. So you may have to rethink your approach.

    2) You mentioned K&T and other "mishmash". This can be a very confusing mess for a "weekend electrician" to jump into. It makes it much more likely that you might frankly screw something up. Maybe you need to call in a pro on this one.
  3. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    First off, a small DIY box of 12/2 is NOT that expensive.

    Second, IS THIS CIRCUIT GROUNDED???
    Meaning, is there are valid ground wire run with the other wires? If not forget the whole thing, you CANNOT use it. You will need to find another newer circuit to use, or run it to the panel.

    I agree with Jimbo, if you are thinking of using power from a light fixture, wouldn't that go on and off anyway???

    To answer your question, NO, do not mix wire sizes. It is just bad practice, and not worth it for $10 worth of wire.
  4. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    It's actually not that complicated. The supply to that specific light is not switched on the incoming side, and the light is about 6 feet from the panel (which has been upgraded in the past). At that point it's all modern wiring with a good ground. I went to HD and bought the 10 feet of 12/2 cable I need. I pretty much made up my mind to use 12/2 while I was posting this question, but was still curious.
    The worst situation I've run across in this house (other than the live bare knob and tube wires sticking up in the foil barrier insulation in the attic), was a run of cable that came out of a junction box for 6 feet to an exposed splice (no box) just above the foundation wall (buried in the insulation), up through the first floor wall to a buried junction box (obviously not code - had to rip apart wall to find it), then up through the wall to another splice (no box) where it connected to the old knob and tube. This was actually the cable that fed the bare exposed wires in the attic which were not connected to anything.
  5. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    It must be or you wound not have asked, would you.
  6. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    The actual hookup isn't complicated, my question was about mixing 12/2 and 14/2. I appreciate all of your input.
  7. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    As long as you are adding a conductor that is within the limits of the overcurrent device what is there to question?
  8. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    Well, I think it's more of a common courtesy to the next guy working on the electrical system. Someone could see 12/2 all over on a circuit and think it's ok to replace the 15 amp breaker with a 20 amp, not knowing a piece of 14 gauge wire exists in the circuit. It seems silly, but I've heard of it happening. Why someone ran 12 gauge wire all over the place on a 15 amp circuit, I have no idea. 12 gauge is a pain to work with when it's not needed. You could argue that it's for future planning, but when you've got 2 to 3 generations of upgrades in the wiring, you shouldn't assume anything's ok to do without deep examination.
  9. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    There may be some 14/2 on the circuit that you don't know about.

    I have seen several places where someone added 14/2 to a circuit that had 12/2 and changed the breaker to 15 Amps. That is a legal way to do it.

    It is pretty easy to mark the panel in some manner that there is #14 on the circuit and that the 15 Amp breaker should not be changed to 20 Amps.

    I think it would be unusual for someone to replace a 15 Amp breaker with a 20 Amp breaker. Most DIYers would not bother with it and professional electricians would (should) not do it without verifying that the conductors are adequate.
  10. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    No,
    It seems stupid not silly and it was probably done by someone who is not in the electrical field.
    This is one of the dangers of the Do-It-Yourself installers and a prime reason to not allow it to happen by anyone other than a licensed person.
  11. 99k

    99k Radon Contractor and Water Treatment

    Messages:
    460
    Location:
    Fairfield Co.,Connecticut
    I could not find this in the code, however, my electrician does and says it is ok to downsize one wire size on a tap circuit that is less than 6 feet. Hence a 12/2 could go to a 14/2 if the total length didn't exceed 6 feet. Comments please.
  12. Speedy Petey

    Speedy Petey Licensed Electrical Contractor

    Messages:
    996
    Location:
    NY State, USA
    Your electrician is WRONG!
  13. The old college try

    The old college try Engineering Technician

    Messages:
    104
    Location:
    MO
    Coming across pretty strong, JW. I'm thinking that a DIY advice forum isn't the place to take out your bitterness and frustration againt DIY'ers. The only advice you've offered is to not do it yourself. Ha.. how ironic.
  14. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    What matters is what the electrical inspector says. Ask your local electrical inspector and see what he says...
  15. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina

    I meant for it to sound harsh as always when I make a statement such as that.

    If a person does not have enough knowledge to know that a conducot rated for 20 or more amps would be okay on a 15 amp circuit or someone who would doubt it should not be making any type of electrical installation.

    There is at least 20 more question that should be asked instead of the question that started this post that would concern this installation.
    None of these have been asked and will not get asked.

    There is enough heat energy in a 15 amp circuit to start a fire or kill in just a couple of seconds. If someone does not know enough to size the conductor then they should just stay away from the circuit all togeather.
  16. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,559
    Location:
    North Carolina
    The inspector being human can be mistaken just as anyone else.

    What matters is what the code says.
  17. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    The code permits, because it does not prohibit, extension of a 12 AWG circuit with 14 AWG conductors as long as the overcurrent protective device is rated at 15 Amps or is changed to 15 Amps when the 14 AWG is installed.
  18. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    Correct and the code is not just the NEC or uniform building codes. Many states have their own modifications to these codes.

    For example I live in Oregon and we have what is called the "Oregon Electrical Specialty Code". On the following link, note that it says...

    Note: The rules and table are for use with your 2008 NEC code book.

    Oregon Building Codes Division, Electrical...
    http://www.cbs.state.or.us/external/bcd/programs/electrical.html

    So ask your *local* inspector for your local rules...
    Last edited: Sep 2, 2008
  19. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    P.S. I have heard of some areas in the U.S. rural south which have no building codes! Basically you are not required to get a building permit in these areas. I don't know if that is true or not or if this would include electrical permits of not? I also heard that it is impossible to get insurance in these areas as well. I wonder why?

    So if this is true, I suppose you could do whatever you wanted in these areas.

    Then what power does a local electrical inspector have? In my area if it is new construction, after you pass the electrical inspection, they give you a little sticker to place on your main electrical service panel. The electric company WILL NOT connect your electrical service until you have that sticker!

    I know of a case where someone remodeled a commercial building in Arizona and they did not get an electrical permit. They did a lot of work - spent thousands of dollars rewiring everything... Well the electric company would not connect the electricity! I think they had to rip a lot of it out and start over.

    So go ahead and argue with the inspector, but your not getting your power turned on if new construction (and you are not doing what the local inspector wants).
  20. jar546

    jar546 In the Trades

    Messages:
    432
    Location:
    USA
    1) Pull an electrical permit and see what the AHJ requires. If there is no AHJ then hire a professional qualified electrician.

    2) Most states regulate radon mitigation installations and the standard for installation is set by the US Government EPA. In my state only certified radon mitigation installers can put in radon mitigation systems. You can install your own but you need to provide paperwork to the state.

    3) The fan must be located outside or in the attic, not inside or you are violating the EPA installation protocol.

    4) A means of disconnect must be present and the circuit must be identified as a radon mitigation system. The termination point of the system is also part of the installation standard.

    5) Pre and Post testing is required.

    6) This is not a DIY job.
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