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Author Topic: need help 50 amp 30 amp is this 220 volt ?  (Read 6675 times)
crown
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« on: August 09, 2010, 12:41:06 PM »

  ok trying to understand is 50 a & 30 a a 220v split in two i have 50 amp and have been testing things with a 50 - 30 a adaper then
  a 15 a adaper and 200 ft ex cord i have a long 220 volt cord for my welder 3 wire can i plug the 30 amp in to this ??
  thanks crown
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Lin
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« Reply #1 on: August 09, 2010, 01:01:25 PM »

Rv connections are 50 amp, four wire (hot, hot,neutral and ground), 240 volt or 30 amp, three wire (hot, neutral and ground), 120 volt.  Your welding cable can run 240 through three wires by using the out of phase hot as a neutral, so it has 2 hots and a ground.  This configuration used to be used for dryers, etc, but I do not think it meets modern codes.  In any case, you can not plug your 30 amp, 120, rv cord into a 240 volt connection.  If however, you are asking if you can take your welding cord and make it into a 120 volt extension cord by changing its plug and receptacle-- you could.
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robertglines1
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« Reply #2 on: August 09, 2010, 01:07:24 PM »

your welder cord even though it looks like a 30 amp receptable is 220 volts and more  should have a different plug pattern than the 30 amp rv 120 v0lt ..ck it out..is your welder 120? if so should work..mine that looks simular is 220 like a electric stove or dryer plug.was typing same time lin was.but will post anyway...Bob
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bevans6
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« Reply #3 on: August 09, 2010, 01:10:20 PM »

Going from highest to lowest...

A 50 amp RV service is 220 volts across two hot legs, each at 50 amps, so you get a total of 100 amps of service.  Each leg is 110 volts referenced to neutral and ground, so you get two 110 volt supplies in your  distribution box, and you balance the loads in the RV across them.  You can also ignore one of the legs, and treat it as a 50 amp 110 volt supply.  If you have appliances that use 220 volt, you connect them across both legs.  This connector and outlet has four leads, two power, one neutral and one ground.  The cord for a 50 amp service uses 6 gauge wire.

A 30 amp RV service is 110 volts on one hot lead, with neutral and ground.  You get 30 amps of 110 volts service.  If you want to plug in a 30 amp cord to a 50 amp RV service outlet, you can use an adaptor that connects your 30 amp plug to one of the hot legs of the 50 amp service only, and connects both neutral and ground to the outlet.  A 30 amp RV plug has three leads - power, neutral and ground.  The cord for a 30 amp service uses 10 gauge wire.  If you use an adaptor to connect your 30 amp RV plug and cord into a 50 amp outlet, it's very important to have a 30 amp main breaker in your distribution panel to protect the cord, since the outlet breaker is 50 amps which is well over what a 10 gauge cord can support.

You can adapt a 30 amp RV service to a 15 or 20 amp outlet using adaptors.  It's important to remember that you can only use up to 80% of the outlet rated amperage on a continuous basis, so you should only draw 12 amps from a 15 amp outlet, and 16 amps from a 20 amp outlet.  If you overload, you will simply trip the breaker, if there is one and it's working properly.

If you have a 200 foot extension cord, you can use it up to it's capacity to carry current and recognizing that a cord that long is going to have a voltage drop that may affect things you need to run in your bus.  You need to know the gauge of the cord wire to tell what will happen.  Personally, most common 14 gauge extension cords are going to be working pretty hard at 200 feet and I would maybe run a TV or some lights, not more than maybe 8 amps of load, but that is off the top of my head.

Your welder extension cord is designed to run a 220 volt welder, so it has two hot legs and ground, but no neutral.  Welders draw a lot of current, usually, so it is probably a heavier gauge wire, but you have  to know what it is and how long it is to understand what will happen.  Since it has no neutral, you can't use it for a proper 50 amp service extension.  You can re-purpose one of the hot leads to neutral and use it to extend a 30 amp or lower service, but you have to be careful about keeping track of what connections you have made.  The common twist-lock three prong outlet and plug is rated for both 110 volt and 220 volt use, you could use that standard, probably, I haven't checked to see what the connection standards are, but my preference would be to put new ends on it that match your bus cords.

There is more detail to all of this, but this is the readers digest version...should help get you started...   Wink

Brian

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Chopper Scott
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« Reply #4 on: August 09, 2010, 06:27:47 PM »

I do know one thing. I just know enough about electricity to get myself in trouble. OK. I know 2 things. I cannot plug my 50 amp 3 pronged plug from my bus into my shop 220 outlets that I use for my welders and such. It blows breakers as I tried to do that once. My main plug to the bus is just a typical 3 pronged 50 amp outlet and when I change it to the shore power the male end of that cord is a 4 pronged 50 amp that I can put adapters from 50 amp to 30 amp to 110. Other than that I am clueless!!! Cheesy
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crown
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« Reply #5 on: August 09, 2010, 06:49:42 PM »

 looks like its a good thing i asked first i thought 50 amp was 220v goining in then split at braker box in two 110 v lines .
 i was trying to test my a/c but when the comp. kiked in the lights dimed and my volt gauge went to 90 so i shut it down
 thats when i thought i could pulg it in to my welder cable but that plug is 3 flat blades and 220 volt how do i wire a cord
 for 30 amp ? thanks
ps i am clueless the 50 amp has 4 wires ?
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john
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TomC
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« Reply #6 on: August 09, 2010, 09:22:41 PM »

As demonstrated by Chopper Scott-there are two different types of 240vac. One is a three prong plug like what is used for a welder or your electric dryer at home.  This is wired for straight 240vac using a positive, neutral and ground.  This cannot be split into 120vac without a step down transformer.
The other type of 50amp service is what is called a two leg service.  You have two positives, a neutral and a ground.  Both positives are 180 degrees apart (or 120 degrees apart if it is split from 3 phase) electrically so that when one leg is positive, the other is negative-alternating the load to the neutral-hence only one neutral wire is needed.  This can be wired (and most commonly on RV) for two individual 50 amp circuits of 120vac.  If you cross the two positive, then you'll once again have a 3 wire 240vac.  Personally- I don't like the hassle of constantly being vigilant about keeping the two legs balanced as to load.  On my bus, my 10kw Powertech is wired straight 120vac, and I just use one leg of the 50amp plug.  6,000watts of power is plenty when parked, and I love that I don't have to think about balancing the loads out.  I like it so much, my truck is going to be wired the same, but using a 12kw Wrico International generator.  Good Luck, TomC
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crown
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« Reply #7 on: August 10, 2010, 04:45:53 PM »

 still confused my welder cable comes from the bracker box its hooked to a double 40 amp bracker one wire to each side then one to
ground so what type of 220 v do i have ? can i wire this a diferent way to get 30 amps thanks john
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john
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Eric
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« Reply #8 on: August 10, 2010, 05:16:57 PM »

The required outlet for a 50 amp rv or bus is a NEMA 14-50r and may I also mention stretching it 200ft will be hazardous without properly gauged wire.. Good luck be safe!
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Chopper Scott
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« Reply #9 on: August 10, 2010, 06:20:44 PM »

Eric (ekhedge) doesn't post a lot on electrical stuff because he doesn't want the controversy. Probably someone you should pm because he does campgrounds for a living.
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bevans6
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« Reply #10 on: August 10, 2010, 06:23:56 PM »

Crown, your welder extension is wired to 220 volt 40 amp service with no neutral.  You cannot adapt that directly to 30 amp RV service.  if you want to re-purpose that cord, you would need to re-wire it so that it is connected to ONE 30 amp breaker only, neutral and ground.  I respectfully suggest that your comments so far have shown you understand the basics and you're asking the right questions, but you don't quite understand the details, so I suggest you get a friend who really knows how, or hire an electrician to install a simple 30 amp RV outlet for you so that you can just plug in a 30 amp RV cord and be done with it.

I quite frankly regard electricity as my friend, but a friend that can bite you, kind of like a cat rather than a nice friendly dog...  I'm not a licensed electrician, yet i have been doing basic wiring for years and have yet to have a job I've done questioned by the State (or in my case Provincial) inspector.  The point is simply this - I've been working with electricity for 35 years, I'm trained in electronics, but that makes me step away from certain jobs as ones I just won't touch.  Just this past week I spent close to $1,000 having an electrician replace the main panel in my house.  Sure, I could have done it, he and his apprentice didn't do anything I couldn't have done, but I chose to spend the money so that I could rest easy knowing that every detail was 100% correct.  He caught some details I did not, so I was happy I asked him to do the job.  If you're not 100% sure about what you are doing with electricity, just back away and get a pro in to do the job.  No harm, no foul, just good old fashioned common sense!

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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