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Thread: Small motor connection

  1. #11
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    Quote Originally Posted by Paul Alciatore View Post
    A terminal block would need to be properly mounted. They should never be laying around loose. I seriously doubt that there is any provision for mounting one in that connection box. Perhaps in other areas of the world that is common, but I have not often seen such provisions in the US. And yes, you could create that mounting method, but few installers would.
    Not only common, pretty much standard. I was pretty confused that WTF you guys are talking about screws+nuts+heatshrink or electrical tape! as all I have ever seen is these already mounted in motors:


    For generic junction box I'd use spring loaded Wago Compact series but no idea if they are alloved in your "code"

  2. #12
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    Quote Originally Posted by Bob Engelhardt View Post
    Yeah ... NFPA 79 is the "Electrical Standard for _Industrial_ Machinery".
    In N.A. It is an extension of NFPA70, National Electrical Code, (NEC).
    The Canadian CEC generally follows this.
    Max.

  3. #13
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    Quote Originally Posted by MattiJ View Post
    I was pretty confused that WTF you guys are talking about screws+nuts+heatshrink
    Wire nuts (screw-on) were banned altogether in the UK about 60+ yrs ago!
    Max.

  4. #14
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    I was unaware of the NFPA prohibition against wire nuts. I don't know why they would not be allowed for motor lead connections, at least for low voltage applications. And since most three phase motors are 240/480 (also low voltage < 600V), I would assume they would be OK for the series connection as well.

    Some info on wire nuts (also called scruits and Marrettes):
    https://en.wikipedia.org/wiki/Twist-on_wire_connector

    Discussion of NFPA 79 - does not apply to residential applications

    https://www.eng-tips.com/viewthread.cfm?qid=194533

    https://forums.mikeholt.com/forum/ac...nnection-boxes

    Raychem Gelcaps were mentioned as an appropriate connector, but they are almost $30 each !

    https://www.te.com/usa-en/product-566376-000.html

    https://www.mouser.com/ProductDetail...20Connectivity



    https://www.ecmweb.com/content/wirin...rial-machinery

    Apparently the "right" way is ring tongue crimp terminals, bolted together, then covered with varnished cambric splice tape, rubber splicing tape, and finally PVC electrician's tape.

    http://www.plctalk.net/qanda/archive...p/t-85156.html

  5. #15
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    Quote Originally Posted by PStechPaul View Post
    Discussion of NFPA 79 - does not apply to residential applications

    Apparently the "right" way is ring tongue crimp terminals, bolted together, then covered with varnished cambric splice tape, rubber splicing tape, and finally PVC electrician's tape.
    No, but a motor is motor, whether home use or Industrial.

    As a Industrial installer, the "right" way is still my preference, in the absence of threaded terminal block.
    Max.

  6. #16
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    Quote Originally Posted by PStechPaul View Post
    I was unaware of the NFPA prohibition against wire nuts. I don't know why they would not be allowed for motor lead connections, ...
    I don't know the reason, but the concern might be the wire nuts falling off. Depending on the application, the motor may be subject to vibration.
    Thermal cycling due to differences in motor temperature when running vs when off might also come into play.

  7. #17
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    First off I have to wonder about the idea that 5hp can be called a "small motor" with a straight face....

    Second I seen my share of machine tool motors that have a fixed terminal plate under the cover.... but I've also seen about an equal number of motors in factory made home appliances that use wire nuts.

  8. #18
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    Home shop? Check.
    Good ol' USA? Check.
    Wire nuts and tape. Check!

    Also, like everything: size is relative. I work in the electric generation industry and have stood next to a motor that is almost 7 feet tall. I don't recall the horsepower but it turns a pump that displaces 250,000 GPM. So to me, 5 HP is relatively small.



    Thanks for the suggestions!
    Tom

  9. #19
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    So to me, 5 HP is relatively small.
    OK, I'll let you have that one....

    Some years back I was on a Honda CBX motorcycle rally that was held up in the interior of BC at a resort just a bit outside of the local town. The resort was almost a town of it's own. And the owner family had at some point dammed a creek on their property where it ran down a cut in the hill they owned. They ran the water backwards through a couple of high capacity pumps which drove some big motors rewound to act better as generators. The system originally ran the resort for a few years independent from the local grid. Eventually the grid arrived on their doorstep and they had to connect. But not a month has gone by other than when they need to shut down for maintenance where they didn't MAKE money selling the power back to the electric company.


    The guy confirmed that running the pumps that way isn't the most efficient. But they had more water than they needed so it worked.

    And the rewound motors converted to generators were around 4 ft in diameter. And old school motors similar to "old sparky" as seen in another recent thread but grown up.

    It was all pretty darn impressive.

  10. #20
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    Quote Originally Posted by flathead4 View Post
    Good ol' USA? Check.
    Wire nuts and tape. Check!
    Tom
    And with the help of a Canadian Invention!
    Max.

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