Page 1 of 2 12 LastLast
Results 1 to 15 of 18

Thread: Electrical Question Wire Gauge

  1. #1
    Join Date
    Apr 2004
    Location
    Comfort, TX
    Posts
    557
    Blog Entries
    1

    Electrical Question Wire Gauge

    Hi all, installing my ClearVue Cyclone. I had it installed in previous shop but I used standard electric cable that goes behind walls and it is too stiff (barely bendable). I want to use something more pliable.

    The 5 hp motor draws 20.8 FLA at 230V. I have a heavy duty extension cord (3 wire) that is 12 ga wire. Can I use the wire from this to power the motor? With appropriate connectors of course and proper plugs.

  2. #2
    You really need that on a 30 amp circuit which requires 10 gauge.

    Mike
    Go into the world and do well. But more importantly, go into the world and do good.

  3. #3
    Join Date
    Apr 2004
    Location
    Comfort, TX
    Posts
    557
    Blog Entries
    1
    Forgive my ignorance on things electrical. I have an outlet that is 30 amps and it was actually wired from outlet to the circuit breaker for 50 amp service. This is from the motor to the outlet. Still need the 10 ga? And thanks

  4. #4
    Join Date
    Sep 2016
    Location
    Modesto, CA, USA
    Posts
    9,879
    12 gauge is max 20 amps. 10 gauge is max 30 amps, 14 is pretty much banned it was max 15 amps. 8gauge is 40 amps etc. runs over 100 feet or so may get downrated.
    Bil lD.

  5. #5
    Join Date
    Jul 2007
    Location
    NE OH
    Posts
    2,615
    The common flexible cords, such as type SO, SOW, SOOW, etc, 12 ga, are rated for 25 amps provided there are only two conductors carrying current (which there would be in this case). So your 12 ga cord is fine. This rating is based on the cable not being installed inside a wall or the like (which doesn't meet code anyway). If you're just running it from your motor to the receptacle on the wall, you're fine.
    --I had my patience tested. I'm negative--

  6. #6
    Join Date
    Apr 2020
    Location
    Tennessee
    Posts
    451
    Blog Entries
    1
    There are several items to evaluate in determining the adequate wire ampacity per NEC. 12 AWG may be adequate given the proper cord insulation ratings and thermal overloads for the motor.
    Is this circuit dedicated to the single motor load?.

  7. #7
    Join Date
    Feb 2014
    Location
    Lake Gaston, Henrico, NC
    Posts
    8,973
    Current flows mainly along the outside of conductors, so stranded wire has more surface area for this flow than the same gauge of solid wire-why there is a difference in the amp ratings.

  8. #8
    Join Date
    Sep 2016
    Location
    Modesto, CA, USA
    Posts
    9,879
    I would not use #12 in a attic in Texas for 25 amps. That supposed 25 amp rating is at 86F. Above that and the allowed ampacity is reduced. I would consider a DC a CONTINUOUS LOAD that means the load is 20.8amps x 1.25 or 26 amps. So your cable needs to be rated for 26 amps at 86 F. #12 is max 25 amps so you are already overloaded at normal temeratures. At only 100F the cable is rated. at 88%. At only 122F it is rated at 75%. I assume the DC is up at or in the ceiling or attic. My attic can go over 150F.
    Bill D

    http://www.interfacebus.com/Cable_Derating_Guide.html

  9. #9
    If this is inside walls I would say definitely it is a no-no. I wouldn't do it outside the wall either because it will cause the cord to get hot and the insulation may degrade over time. If you want something more flexible to go in the wall, I would use 8 gauge wire. At least where I live, it comes stranded. It is overkill for 30 amps but there is no issue going up in size (other than cost). You can probably also find stranded 10 gauge.

    I don't even like running 12 gauge in the walls. 14 is so much easier. But I think it pays to not cut corners with electricity.

  10. #10
    OP Wrote:

    Forgive my ignorance on things electrical. I have an outlet that is 30 amps and it was actually wired from outlet to the circuit breaker for 50 amp service. This is from the motor to the outlet. Still need the 10 ga?



    I may be misunderstanding, and I'm not electrician, but I believe that the outlet should match the breaker. This is either in the electrical code, or at least good practice. That is, if you have a 30amp outlet it should be paired with a 30 amp circuit breaker...that way everyone gets what they are expecting. If you have a 30amp breaker connected to a 30amp outlet with 50amp wiring in between, then I think there is no issue however.

    I have a 5hp ClearVue cyclone. I have a 30amp breaker and 30amp locking outlet, which I ran with 8 gauge Romex. The romex is tucked up into the space where the cinderblock foundation meets the ceiling, with the other wiring. I made an extension cord with 8 gauge stranded rubber-coated extension wire of the SO/SOW type mentioned above to go from the outlet to the remote control box of the dust collector. From that box to the motor is another section of the rubber extension wire. My DC is in a closet...well 3/4 of one. Eventually I will close it off completely at which point I will switch the motor wire from the rubber cable to armored cable (can't have cords in an enclosed space), i'll use new 8 gauge solid wires inside the armored flex....the rubber extension cords should not be run inside armored flex tubing.

  11. #11
    Join Date
    Jul 2007
    Location
    NE OH
    Posts
    2,615
    Quote Originally Posted by Tom M King View Post
    Current flows mainly along the outside of conductors, so stranded wire has more surface area for this flow than the same gauge of solid wire-why there is a difference in the amp ratings.
    This is true for AC current but is dependent on frequency, being much more pronounced at high frequencies. At 60 Hz, the skin depth is about 8 mm which means for conductors on the order of 12 ga the effect in negligible. The main reason stranded conductors are used in this gauge range is to improve physical flexibility.
    --I had my patience tested. I'm negative--

  12. #12
    Join Date
    Feb 2013
    Location
    Tippecanoe County, IN
    Posts
    836
    Quote Originally Posted by Paul F Franklin View Post
    This is true for AC current but is dependent on frequency, being much more pronounced at high frequencies. At 60 Hz, the skin depth is about 8 mm which means for conductors on the order of 12 ga the effect in negligible. The main reason stranded conductors are used in this gauge range is to improve physical flexibility.
    Yes. And the reason for the higher current rating is all about temperature. It's easier for an extension cord to stay cool than it is for romex buried in insulation inside a wall. Of course the temperature rating of the insulation plays a big role too.
    Beranek's Law:

    It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
    L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

  13. #13
    Join Date
    May 2017
    Location
    Metro Atl, GA
    Posts
    20
    Quote Originally Posted by Scott Bernstein View Post
    I may be misunderstanding, and I'm not electrician, but I believe that the outlet should match the breaker. This is either in the electrical code, or at least good practice. That is, if you have a 30amp outlet it should be paired with a 30 amp circuit breaker...that way everyone gets what they are expecting. If you have a 30amp breaker connected to a 30amp outlet with 50amp wiring in between, then I think there is no issue however.
    What if the OP outlet was a standard 15A 110V Plug and had 50A wiring and a 30A breaker? I don't think you are suggesting the outlet be replaced with a 30A capable 110V outlet. The breaker is there to protect the wiring and the outlet. The outlet configuration is chosen to limit the possible current draw from the device (load) - and assumes the device wiring and plug are consistent with its load. Outlets for some devices - welders for example, often have breakers rated above that for wiring and outlets.

  14. #14
    Quote Originally Posted by Mark McClurg View Post
    What if the OP outlet was a standard 15A 110V Plug and had 50A wiring and a 30A breaker? I don't think you are suggesting the outlet be replaced with a 30A capable 110V outlet. The breaker is there to protect the wiring and the outlet. The outlet configuration is chosen to limit the possible current draw from the device (load) - and assumes the device wiring and plug are consistent with its load. Outlets for some devices - welders for example, often have breakers rated above that for wiring and outlets.
    As I said I'm not an electrician....but the electrical code I believe really gets into the weeds and says something along the lines of this: If there is a single outlet on a branch circuit, the amp rating of that one outlet should not be less than the amp rating of the circuit (breaker). Again, I could be wrong about that however that is my understanding... If there is more than one outlet on a branch circuit, the individual outlets may be rated at a current less than that of the circuit (breaker). A typical double (or "duplex") outlet counts as two. So if there is a single outlet (not a double...one single receptacle) on a circuit with a 30amp breaker I personally would use a 30amp outlet. I assumed that the OP had a dedicated branch circuit specifically for his dust collector with a single receptacle on that circuit (again, not a double outlet with two receptacles).

    In my garage, in addition to three 220V 30amp circuits each with a single 30amp locking receptacle, I have 5 20amp 120V circuits, each with a single duplex outlet rated at 20amps. I had noticed before I did the additional circuits that some of my tools popped the breakers on the existing 15amp circuits, so I added those additional 20amp circuits. I purchased individual wire strands and ran them all in armored flex line, mounted around three sides of the garage just above waist level. I am planning to add a few more dedicated outlets for the three infra-red heaters I have in the shop, mounted on the ceiling.

  15. #15
    Join Date
    Feb 2013
    Location
    Tippecanoe County, IN
    Posts
    836
    Quote Originally Posted by Scott Bernstein View Post
    As I said I'm not an electrician....but the electrical code I believe really gets into the weeds and says something along the lines of this: If there is a single outlet on a branch circuit, the amp rating of that one outlet should not be less than the amp rating of the circuit (breaker). Again, I could be wrong about that however that is my understanding... If there is more than one outlet on a branch circuit, the individual outlets may be rated at a current less than that of the circuit (breaker)...
    Here's what the code says:

    210.21(B).jpg
    210.21(B)(1).JPG
    Beranek's Law:

    It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
    L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •