Can I plug my 50amp cord from my class A into a dryer outlet?

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DonTom

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Depending on how far you want to go back, in the mid 1950's when I was wiring houses with my father, the ground and neutral was run as a single conductor from the panel.
I have no clue how dryers were designed back in the 1950's. Perhaps the entire drier then ran from 240 VAC unlike today where they usually have a 120VAC motor and 240 VAC heating element.

-Don- Medford, OR
 

DonTom

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But the unknown part is that what determines the current one receives is a combination of the voltage applied,
Yep, but the more voltage means the body draws more current. Double the voltage, you also double the current and then have four times the wattage or four times the power to kill a person. However, I know it's a bit trickier than that.

For an example, the old electric chair. If they increased the voltage and the body drew more current, you were more likely to live. Because what would happen is the heart would stop and then restart from the extra high current. The exact voltage was rather critical, could not be less or more for a quick kill than what was used (2,450 volts AC). 15 seconds at six amps average.

-Don- Medford, OR
 

DonTom

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"Can I plug my 50amp cord from my class A into a dryer outlet?"

Not only a "yes" but if you have a 50 amp 14-50P you can run BOTH your A/C units unlike the 30 -amp service in an RV park.

But if you have an RV30-P, it does you no extra good as it cannot use both lines.

Seems to me the 50-amp RV service is an overkill, unless you have three A/C units in your RV and more.

-Don- Phoenix, OR
 

Kirk

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If you really want to know how electricity kills and what it takes to do the job, read this article. In reality, most of the time when shocked we get lucky and are just fine but given the wrong circumstances it take only a tiny amount of current and not a lot of voltage to cause it. But the best practice is to be careful and avoid shocks from any voltage.

How Does Electricity Kill?


As they used to say in the Navy electric safety course: "There are old electricians and there are bold electricians, but there are very few who are both."

The short-term and long-term effects of electric shock on the human body

 
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DonTom

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I have too much power, said no one ever...
True, having too much power available is never an issue, but needing more than that 60 amps total available from a 30-amp DRYER outlet is unlikely. 24 amps per line is more realistic because of the 20% safety margin required, but that should be enough for a couple of A/C units, converter and more. Still is 2,880 watts per line.

IIRC, most RV A/C units are around 13 amps or 1,560 watts each. Too bad the RV-30 outlets at RV parks and all 30-amp RVs are not designed that way. I assume the RV-30 was an old (and very stupid) design. Again, somebody should have asked me first! :)

I would be thinking of the future and try to be ready for it. Perhaps the RV30 will soon be phased out and we will only have 14-50R/P. Like this RV. That will even be better than the drier outlet by 40 amps (20 amps more per side at 120 VAC than the dryer outlet).

-Don- Phoenix, OR
 

DonTom

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While I can't provide any sticical data to support it, there is absolutely no doubt in my mind that the answer is yes
I ain't that sure and I do have doubts. Especially if all the wires are connected correctly on the 3-prong. The frame of the drier will still be ground. One would have to try very hard to get shocked by only touching a ground. And if they also touch a hot somehow, you have the exact same issue as when on a four prong.

I am not saying it cannot happen, but I sure would like a real-life example of what makes the four-prong safer. I cannot figure out a way to shock myself on a correctly installed 3-prong to any more of a degree than on a four prong.

But as I said, I think four possible wires should have a plug to match regardless.

-Don- Phoenix, OR
 

Boat Bum

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I appreciate everyone's contribution to my thread and to show that I documented my experience with pictures.

Plugged in the 50amp extension cord into the four hole dryer outlet:
IMG_20220807_093404.jpg

Ran it out to the 50amp coming out of the coach:


IMG_20220807_092649.jpg
IMG_20220807_093103.jpg

50 amps, DonTom was right on.
IMG_20220807_093232.jpg
 

DonTom

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I appreciate everyone's contribution to my thread and to show that I documented my experience with pictures.

Plugged in the 50amp extension cord into the four hole dryer outlet:
View attachment 156341

Ran it out to the 50amp coming out of the coach:


View attachment 156342
View attachment 156343

50 amps, DonTom was right on.
View attachment 156344
The four prong drier plug is still a 30-amp outlet at 240VAC just as is the 3-prong dryer outlet. That means twice to current capacity of a RV-30 at 120 VAC, or 60 amps total with no more than 30 amps per each line of the two 120 VAC lines. 24 amps per line with the 20% safety figured in, so you're good for a total draw of 48 amps at 24 amps each line at 120 VAC.

So your total max current capacity at 120 VAC is double a 30-amp RV outlet but 40 amps below a 50-amp RV outlet when using that dryer outlet.

-Don- Phoenix, OR
 

DonTom

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If you really want to know how electricity kills and what it takes to do the job
"This (four-prong) eliminates the possibility for a ground current traveling to the machine, as it features a separate return path for unused power."

I found that here.

Still doesn't sound any safter to me. Frame is still ground either way, separate path or not. And the ground could still open on a four prong as easily as a 3-prong.

Any difference in ground current between the 3-prong and the 4-prong should be negligible and the difference certainly not dangerous when properly wired to a three prong.

So where is the safety issue?

-Don- Phoenix, OR
 

Gary RV_Wizard

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Boat Bum...
Your Power Control System display will show "50 Amps" whenever it sees more than about 200v between the two hot wires (L1, L2). It's not testing & showing the actual available amps - just distinguishing between standard RV 30A service and 50A service. It doesn't know or care that you are using a 30A/240v source instead of 50A/240v .
 

DonTom

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There is NEVER any current in a ground wire UNLESS there is a short.
Not always exactly true. See my link in message #51.

"The 4-prong dryer cord is comprised of two hot wires, a neutral wire and a ground wire. This creates a separate return path for unused current."

And if you want to include HF frequencies, you can get one hell of a burn from a ground wire. You may ask me how I know.

But I do not see the big danger difference between the 3 and four prong safety. At least not enough to be concerned with.

-Don- Phoenix, OR
 

DonTom

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Perhaps you should take that up with the professional electricians and engineers on the NFPA's Committee on the National Electrical Code, which is actually a set of 20 expert panels plus a coordinating group.
If I were on it, I would have to straighten out the other 19 people! ;)

But are you saying of all the electricians in this forum, and other technical people, like you, Mark, Kirt, Lou and others (and myself) have no idea how to answer such a very simple question about the safety difference between the 3 and four prong dryer outlet? I need to go talk to that committee to go find out?

If that's the case, I am already decided that the three-prong is equally as safe as the four-prong. And I am betting my life with it because BOTH of my homes have the three-prong.

-Don- Phoenix, OR
 
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Pedro Dog

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I have a BSEE from a very good university, plus many graduate courses on electromagnetism and 32 years of practical hands on laboratory work. I know what I'm talking about

"The 4-prong dryer cord is comprised of two hot wires, a neutral wire and a ground wire. This creates a separate return path for unused current."

The author of this sentence is not very clear. The "unused current" is actually current carried by the ground wire when there is a short.

Just google "do ground wires carry current"

You will find plenty of material that will make things clearer for you.
 

DonTom

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And that is the reason that there no point in any of us responding.
Kirk, sorry about the name. But I bet I am not the first to make that mistake! Just like I am often called "Tom". And I have even more issues with my last name.

And if somebody here can explain it, there is a very good reason to do such. But until then, I will not see the safety issue difference between the 3 and four prong, because I cannot figure it out. But perhaps somebody else here can. I am simply waiting for somebody to explain why a 4-prong is safer than a 3-prong when both are wired correctly, and each has a good ground.

The only difference is one ground also has the neutral wire and the other doesn't. Still a ground with very close to 0.00000 AC volts either way.

That just doesn't sound like the 3-prong is more dangerous to me. Does it to you? If so, why?

-Don- Phoenix, OR
 

DonTom

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do ground wires carry current
Of course they can. The ground can even have the entire current of all the loads. And it can also have no current at all. It depends.

Take a 12-volt car engine starter for an example. One side is hot, the other side is grounded. If the starter motor itself is not grounded at the case, the current in the grounded negative wire is the exact same as in the positive starter wire and that is a lot of current.

-Don- Phoenix, OR
 
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