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Thread: NEMA 14-50P to L14-30R

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    NEMA 14-50P to L14-30R

    If I purchase such a pre-manufactured cable (in the title), what is the desirable AWG wire size? Is 10 sufficient? Home Depot has one available. It would be going into a generator panel from (hopefully) a Miller 260 Bobcat. Thanks for any feedback.

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    Re: NEMA 14-50P to L14-30R

    Quote Originally Posted by mule47 View Post
    If I purchase such a pre-manufactured cable (in the title), what is the desirable AWG wire size? Is 10 sufficient? Home Depot has one available. It would be going into a generator panel from (hopefully) a Miller 260 Bobcat. Thanks for any feedback.
    I've never heard of a 260 Bobcat. 250 Bobcat is a 10,000 watt generator. National Electrical Code requires an upsize to 125% but I'm unclear if the circuit breakers integral limit that. I would size the adapter cord 3'? long to not overheat. I make it a 41.66 Amp generator. It won't likely carry full load for long periods. #8 cable (copper) is good for 40 Amps at low temp, but often, manufactured cords are made of 90 or even 105 degree Celsius rated.

    In a less confusing answer, I'd look for #8 or #6, preferably #6.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

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    Re: NEMA 14-50P to L14-30R

    Thanks Willie B. Miller no longer makes the 250 Bobcat. If they did, I would buy it. The replacement is a 260 with a remote start FOB. Check out Millerwelds.com for details. I appreciate your advice which confirms my suspicions . My reason for posting is that I already have a Honda 5000 generator which connects to a generator panel with a L14-30 into the generator. I just want to be able to switch the cable from the Honda to a Bobcat (which I'm in the process of buying but delivery is not expected to my local provider until late April.) I was suspicious that the #10 wire is not enough but that is what is in the pre-fab cable selling at HomeDepot.ca. I'll continue to search until I find heavier wiring and perhaps have an electrician to fab the cable. Thanks so much.
    If anyone knows of another source for the pre-fab cable, a link would be appreciated. Allan

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    Re: NEMA 14-50P to L14-30R

    To Willie B - I just checked the cable normally used to hook up the generator. It's about 50 feet long, 600v, 10/4 wire and plugs into a 120/240 receptacle which goes back to a generator pony panel . I checked the Honda manual and the 120/240v is 37.5/18.8A in AC output. Extension cables under 60 meters wire should be 1.5mm sq. I went to a Metric/AWG sizing chart and it puts the size at between a 14 and 16. Over 100 M at 2.5 mm sq the AWG size is between 12 and 14. I'm not an electrician but it seems the cable size at 10/4 would be ok. It's probably not the same as would be required if a plug from a panel was to be set up for the maximum voltage equivalent of the Bobcat. Does that sound right? Not understanding electricity makes it hard for me to even get the terminology correct.....
    Last edited by mule47; 03-26-2021 at 09:06 PM.

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    Re: NEMA 14-50P to L14-30R

    Quote Originally Posted by mule47 View Post
    To Willie B - I just checked the cable normally used to hook up the generator. It's about 50 feet long, 600v, 10/4 wire and plugs into a 120/240 receptacle which goes back to a generator pony panel . I checked the Honda manual and the 120/240v is 37.5/18.8A in AC output. Extension cables under 60 meters wire should be 1.5mm sq. I went to a Metric/AWG sizing chart and it puts the size at between a 14 and 16. Over 100 M at 2.5 mm sq the AWG size is between 12 and 14. I'm not an electrician but it seems the cable size at 10/4 would be ok. It's probably not the same as would be required if a plug from a panel was to be set up for the maximum voltage equivalent of the Bobcat. Does that sound right? Not understanding electricity makes it hard for me to even get the terminology correct.....
    Will the Bobcat have a circuit breaker protecting the NEMA 14-50R? Will you have an input breaker in your generator panel. Miller specifies 11,000 Watts Surge. 11,000/240 Volts is 45.83 Amps.

    I don't know the temperature rating of your cord, it won't likely be rated more than 90 degree C. #10 is good up to 40 amps, but code limits circuit breaker size protecting #10 to 30 amps or less.

    Thus far, we have discussed overheating the cable. Voltage loss is another matter. The formula is: (K x I x L x 2)/ Ed = CMA
    K is resistance in ohms for a 1 CMA (Circular Mil Area) Copper K factor is 12.9
    I is Amps
    L is length in feet
    2 because electrons travel round trip.
    Ed is your acceptable voltage loss

    12.9 x 45.83 x 100? x 2 / 7.4 = 15978

    #10 is only 10380 CMA
    #8 is 16510 CMA

    You will plug in your own values for each factor , so your answer is maybe.
    I would choose #8, or if I choose #10, I'd add a breaker for input limiting load to 30 amps. Even a 40 amp breaker would prevent overheating a #10 cord if it is rated at 90 degree C.

    My adapter cord for my Bobcat 250 came from Miller. It is outdoor rated. An assembled cord from components won't likely be outdoor rated, and it'll cost more.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

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    Re: NEMA 14-50P to L14-30R

    To Willie B - I just checked the cable normally used to hook up the generator. It's about 50 feet long, 600v, 10/4 wire and plugs into a 120/240 receptacle which goes back to a generator pony panel . I checked the Honda manual and the 120/240v is 37.5/18.8A in AC output.
    Bill (Willie B) will never steer you wrong. But I have to ask. Are you changing anything on the load end of the equation? That is to say are you adding more circuits, or are you still going to run the same loads that you were feeding with the Honda generator? If the load end (i.e, the current demand) isn't changing, why not just go with one of these and keep the cable you have today?


    https://acworks.com/products/s1450l1...50p-to-l14-30r
    Miller Multimatic 255

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    Re: NEMA 14-50P to L14-30R

    Since the first caveman got his first Homelite generator, man has searched for a cheaper way to connect his whole cave to a generator without a transfer switch.
    These days most manufacturers of breaker panels offer interlock kits. Available for many from their manufacturer, other panels can fit one from Interlock Technologies. These work only on panels with a main breaker & use an added breaker in position 2-4.

    The reason I say this, is the added breaker could be sized to protect the cord & the generator from overload. Then, if you add too much load, it trips and you have to reset it.

    I haven't installed a Gen Tran style transfer in at least ten years.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

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    Re: NEMA 14-50P to L14-30R

    Willie B -

    Thanks for sticking with me on this matter. I appreciate your input and can clearly see you are interested in sharing your knowledge, as is Louie1961.
    The CSA approved (yes, in the Great White North) generator panel (in which the critical circuits are located), is 60A rated with some room for circuits still available. We are careful not to cause the breaker on the Honda to shut down, by using energy efficiently in emergencies, and it never has. With the panel output on the Honda rated as "120/240v is 37.5/18.8A in AC output.", I thinking I'm safe as far as demand is concerned. The power receptacle on the 260 shows a 50A breaker.

    The Bobcat is intended to be a hobby welder (expensive hobby) primarily but I wanted to have the generator option. I'll use the Honda until it dies. I find regular running, under some load, oil changes every 6 months at the latest, ethanol free gas (High Test) with stabilizer, keeps it smooth and it will be 20 years old this year. My reasoning for getting the Bobcat is my concern about impending inflation. I'm not wealthy but if we go into serious inflation I'll never be able to get the Bobcat as the value of the dollar drops. Critics tell me I can't eat a welder, but I can't eat worthless dollar bills either. The welder would hold value much more than paper or digital dollars as long as gas is available.

    Thanks again to all! Allan

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    Re: NEMA 14-50P to L14-30R

    Louie1961 - I did write a thank you note for the link (which I had been eyeing) and I've decided that's the one for me. I'll get one after I get the welder. I obviously forgot to hit the submit button after getting called away from the computer. Thanks again. Allan

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    Re: NEMA 14-50P to L14-30R

    At the last minute I was offered a new Trailblazer 325 EFI with Excel, after a deal fell through with another customer. I bought it and am ecstatic. There is still quite a wait for a Bobcat, not that I'm in a hurry. I was wrong about the cable requirements. I had ordered a NEMA 14-50P to L14-30R and later received the welder. Then I discovered that the receptacle I needed to accommodate the power plug at the end of that cable was a L14-20R, not the 30R. They have one different prong shape. Apart from the electricians on this site, directed to people like myself, one prong tab on the 30R goes inward to the centre of the plug. The 20 plug pin had a tab which points outward from the core of the plug or receptacle. Not being literate in electrical terminology, I eventually got through, with the help of a very understanding and helpful clerk at an electrical outlet. So I bought a L14-30P and a NEMA L14-20R, attached them to the ends of a meter long 10/4 cable as per clear instructions. Now I have a successful setup to use the Trailblazer as an emergency generator. The cost total of the combined cables was about $134CAD. While that's a lot of loot, it’s well worth it if a power outage occurs. This is feedback to those who gave advice on my question. I'm impressed with the knowledge of these seasoned welders/fabricators, etc. Thanks!

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