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  • Bubba
    replied
    I don't know if Menards are national or just in the midwest but I got my connectors there. They were $10 each. Yes $10. I actually built a strip out
    of 4 females of 6-50-R for the MM210, Dyn200DX, and the plasma.
    I never use 2 at the same time so all could be wired in the same 40A circuit.
    This way I have all plugged in. I know the Supply houses prices I started there myself......

    Leave a comment:


  • Sberry
    replied
    I see this thread got pretty deep. 15 and 20A recepts,, hmm,, they are defined that way to allow the type of plug to be used. They want to make sure true 20A equipment doesnt get plugged in to less than 20A circuits. As for the wire having to match the breaker ampacity, no it doesnt. Read ART630.11 NEC specifically to welding machines. Some of them allow number 10 wire and 60A breakers. For the 180 in question here use a common 6-50-R recept and a P plug, number 8 wire and a 60A breaker as per the manual. As for the small air comp if this is a dedicated circuit (so you cannot plug other devices into it as was indicated) you can change the breaker to a 30 to keep it from tripping on startup. The motor has its own thermal to protect the wire from overload, the breakers purpose it to provide short circuit interuption.

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  • INTP
    replied
    Originally posted by hankj
    ...
    Later guys. I'm gonna open a beer...

    Hank
    Not fair at all. I'm still at work!

    Leave a comment:


  • hankj
    replied
    Hey, Karl,

    I know some civil engineering stuff, like the "three guarantees for poured concrete": 1. It'll get hard. 2. It'll crack. 3. Nobody will steal it!!

    Later guys. I'm gonna open a beer...

    Hank

    Leave a comment:


  • INTP
    replied
    The compressor trips the breaker because it's a crappy single stage unit. Starting current is just over 50A, but only for a fraction of a second. Running current is 13A. FWIW, the circuit it is on has exactly one receptacle, something I forgot to mention earlier. The compressor will get replaced with a 240V 2-stage one, as other priorities are accomplished.

    Karl, as I read what you're saying, the only thing we are seeing different is about the rating of the receptacles. I see your point, and I tried to express mine. I am certainly not trying to dissuade anyone from following your advice. Just my side of the discussion.


    The 15A receptacle allowance on a 20A circuit is an interesting example of the ambiguity of the NEMA ratings. The NEMA rating can be seen as an indicator of the ampacity of the receptacle itself, or it can be seen as an indicator of the ampacity of the circuit. I interpret that in the 15A receptacle on the 20A circuit, it is the latter. In any case, I think the NEMA 'ratings' are ambiguous in some situations.

    Perhaps we should all just hard-wire our 180SD's, since there doesn't seem to be a single phase, 240V, 3-conductor, 70A option (or none that I could find).

    Barry

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  • kdahm
    replied
    15A Receptacles, 20 A Breakers

    Because NEC expects that multiple point loads will be applied to the circuit, such that each receptacle is loaded to below 15A, but the total load on the circuit is below 20A? I would ecpect there is another provision that requires a 20A receptacle if a single load on the circuit is expected to exceed 15A.

    You can follow the NEMA spec if you use a item in accordance with its manufactured intent and labeled rating. But that's just quibbling. Follow the code, and use products as labeled.

    Besides, I'm a civil engineer, not an electrical one. If something is moving, it's got to be broken.

    Karl

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  • hankj
    replied
    A little water (or more fuel?) on the fire:

    There is no NEMA spec to "follow". The National Electrical Manufacturer's Association (NEMA) has adopted a set of standards that define minimum production requirements. As a standard, it just exists. You can't "follow" it. NEMA references appear in the National Electric Code (NEC) because the National Fire Protection Assoctiation (NFPA - the publisher of the NEC) recognizes the validity of the standard.

    I also read a statement somwhere in the replies that said something to the effect that the receptacle should always be rated higher than the expected load? If this is the case, why does the NEC allow 15A receptacles on branch circuits protectd with 20A breakers?

    Ahh, the nuances!!

    By the way, INTP, if you can rewire that compressor motor for 240V, it'd be happier!!

    Hank

    Leave a comment:


  • kdahm
    replied
    Sorry for being unclear

    My response was to INTP

    I agree that 3 phase plugs can be wired as single phase. My only problem is that if the receptacle is wired single phase instead of three phase, a future user may plug in three phase equipment and expect it to work. I don't know enough to say if it could be a safety hazard, but it should be clearly labeled as single phase both in front and inside the box, possibly with a tag on the wiring.

    I probably sound a bit paranoid about doing thing correctly, but I have tried to repair machinery at work that is 30-40 years old. Previous people working on them had changed the wiring so it didn't match the factory diagrams (when available), and nothing is ever labeled. After a few hours of tracing leads to find a problem, the urge to cause bodily damage to those who don't label things or don't do them correctly becomes appealing.

    Personally, I'd rather have a SD 180 and wonder how to wire it, than not to have a SD180 (or anything close) and not need wiring.

    Karl

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  • ASKANDY
    replied
    He said he could get 60 amp 3 phase plugs free and the answer is still yes, you can run it single phase at 60 amps no problem.

    A-

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  • kdahm
    replied
    INTP - 20 Amp plug, 30 amp breaker??

    That is A Bad Ideatm

    If you really have a problem with the air compressor tripping the breaker on startup, go to a 20 amp slow blow breaker. If you want to use a 30 amp breaker, you MUST use a plug rated at 30 amps minimum.

    Anything else is folly.

    Sure, you can get away with it for a while. The NEC has a bit of slack built into it to allow for transient loads and natural variabilty. Responsible manufacturers put in a factor of safety because of variations in quality and to allow for end user error. One person, with one receptacle, can beat the odds temporarily.

    One thousand people, each with one receptacle, will experience fires and shorts.

    Sure, you know that the socket you labeled "30 amp" is a 20 amp socket. When you sell, will the next owner of the shop know? Will you remember to change the breaker, the receptacle, or the label before leaving? When a fire starts because he plugs in a 30 amp load, you will be at fault.

    Look at the fire this weekend on a Canadian submarine fresh out of refurbishing. One officer died and at least six are seriously injured due to an electrical fire that started in one subpanel, spread to the main panel, and knocked out power to the entire boat. Millions of dollars damage, and hte investigation is just starting.

    If the breaker is tripping, and it is the recommended size, find out why. Don't just flip a bigger breaker in and assume the problem is solved.

    Finally, if you suggest someone else follow NEC and NEMA spec, don't turn around and tell them that you are disregarding it.

    Respectfully
    Karl

    Leave a comment:


  • INTP
    replied
    It's analagous to the reason that you always use red or black for the hot wires and white for the neutral. As far as conductors go, the color doesn't matter. But someone later may be servicing the circuit and if you didn't follow the standard, they could get hurt or could wire something in a way that damaged equipment that is hooked up to the circuit. Switching the hot and neutral on a lamp circuit can make the difference between getting shocked and not getting shocked, although the light will work either way.

    So if someone comes along later and sees a three phase receptacle, but it's wired for single phase, they may think they can plug in their three phase motor and instead of it working correctly, it could overheat and start a fire. That's where I was going on this.

    Part of the NEMA spec is to act as an indicator of the circuit capacity (or ampacity as it were) and prevent misuse of the cirucuits. The dryer outlet that is rated at 30A tells you that the capacity of the wire is 30A (10GA) and is on a 30A breaker. You can tell by looking at it that you shouldn't put your 50A welder on there. Similarly, you generally shouldn't use a 50A receptacle with 10GA wire, because someone should be able to assume that the conductors can handle 50A, which would be untrue in this case.

    The NEC has many rules, and many exceptions, and I'm not up to speed on all of the exceptions, though I have a grasp of the basics. Dedicated welding circuits are one case of exceptions, as are motors that have a higher starting load than running load. If it really interests you, you can spend a lot of time getting to know it (years, actually).

    The breakers are there to protect the wires from being overloaded, (which causes them to overheat.) I never put a breaker on a circuit where the breaker rating is greater than the ampacity of the conductors. I've put a 115V 20A receptacle on a 10/2 wg wire with a 30A single pole circuit breaker and labeled the receptacle as '30A' though, and I am confident I'm not going to overheat the receptacle. (This was to prevent my air compressor from tripping the 20A breaker on startup, since it surges to as much as 55A on startup.)

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  • deepcj7
    replied
    Originally posted by INTP
    I would think that using a 3 phase receptacle, wired as single phase would be more dangerous than putting a NEMA 6-50 on 6/3 wire and a 60A breaker. Part of the safety of the NEC is to avoid danger to persons who will service the wiring, as well as preventing damage to connected equipment.
    Could you expound on what your saying. I don't understand what the danger is, I can't tell the difference between single and 3 phase plugs except that it's printed on the body of it. I am by no means a electrician.
    Thanks for all who have posted.

    Leave a comment:


  • INTP
    replied
    I would think that using a 3 phase receptacle, wired as single phase would be more dangerous than putting a NEMA 6-50 on 6/3 wire and a 60A breaker. Part of the safety of the NEC is to avoid danger to persons who will service the wiring, as well as preventing damage to connected equipment.

    Leave a comment:


  • ASKANDY
    replied
    Sure.
    A 3 phase plug can be wired for single phase, just drop one hot lead. The only thing is that it now is a dedicated plug and receptacle that no other machines can plug into. At least no one can come and borrow your machine!

    Andy

    Leave a comment:


  • deepcj7
    replied
    Originally posted by kdahm
    worth exactly what you paid for it.

    Having the exact plug rating for the amperage is irrelevant. It is critical, though, that the plug is rated higher than the expected amperage.

    The breaker should have the lowest rating in the system. Always!

    Looking at two examples:

    1. Your coffee maker is busy running all day, and it's a real power hog. It even runs on 230v. You change the plug out to a 50a,230V Nema 6-50 and change the power cord to a #4. The line from the breaker box is a #2. The breaker you select is rated at 10 amps.

    Regardless of how much coffee is made, the breaker will always trip before the rest of the system gets close to melting. You may have spent a lot of money that you didn't need to, but the circuit is safe.

    2. Frank D. Clueless is wiring a Synchro 180 in his garage. He sees that it needs a 70 amp breaker, so he goes to the Orange Store and gets one. The circuit is wired with some 14/3 lying around from a ceiling fan project, and a standard 3 prong 110 volt socket used. There is a spare lamp cord hanging up, so it replaces the original cord and plug. The ground is not connected between the machine and the socket. Of course, it is wired at 230v.

    He starts welding. Several things may, and probably will happen.
    a. He gets the shock of his life when touching the case, because of no ground and poor maintenance.
    b. The lamp cord melts
    c. The plug and socket melt and catch on fire
    d. The wiring between the breaker box ond the socket melt and catches on fire
    e. The new 70 amp breaker does its job nicely and stays closed, because it never sees 70 amps.

    If Frank had used a 15 amp breaker, wired everything at 110 volts, and used a ground between the machine and the plug, he may have been acceptable. Welding performance will not be very good though.

    In other words, use a 50 amp circuit if that is what is cost effective. Do not, however, install a larger breaker without making sure that the wiring and the plug are rated at least as high as the breaker.

    Note: See NEMA standards, the NEC and local codes, and consult a licensed electrician for actual requirements. I am not, nor have I ever been, a professional electrician.

    Karl
    You are absolutly correct. That is why I'm avoiding the easy route and purchasing 50 amp products. I think I may have a lead on free 60 amp plugs, but they are for 3 phase 240V. Can these products be wired up for single phase? The plug has 4 blades and a pin, hopefully instructions come with it.

    Leave a comment:

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