Plugging 30A 5th wheel into 50A service

Spridle wrote:
this is the definitive answerer. You cannot safely connect a 30 amp #10 gauge cord to a 50 amp service using an adaptor without proper 30 amp protection. 2008 National Electrical Code NEC/NFPA 70 240.4.(D)(7). The adaptors from Wal-Mart and elsewhere are not protecting the 30 amp cords and are a violation of the NEC NFPA70. Yes they work but violate the National Electrical Code. You are simply skating on thin ice. Find a way to protect the cord with a 30 amp maximum 120 volt or greater fuse or circuit breaker directly after the adaptor. This is a simple engineering rule. No unprotected or under-protected wiring. Protection goes ahead of the wiring not after.

Correct!!!!

The adapters that are sold up here in Canada have a CSA approval on them but do say "must be used with a 30A circuit breaker". So this would cover their azz. But no one is going to replace the 50A breaker with a 30A.

We all have them and we all either use them or have used them. Some knowing the minimal risk, some not.

full_mosey wrote:
Hi Coach-man;

You don't get a single Volts reading from a 50A receptacle. There are two 120 Volt circuits, one at the 9 O'clock and the Other at 3 O'clock. You measure each separately to Neutral(6 O'clock).

It is likely that one of the 50A legs was 90V.

Now, back to your 50A -> 30A pigtail question. I use one whenever I can. I also use a 30A -> 20A.

However,it is wrong to do so by the book. The long answer, which I already explained but you have not grasped yet, is that circuit breakers protect downstream wiring. The 30A cable going into your RV is upstream from the 30A breaker. Technically, that cable is unprotected by the 50A breaker.

HTH;
John

Your all Nuts! When you plug a tee bone adaptor into a 50 amp plug, you will only see one side of the two L1, L2 hot leads, that is the only way this will work! As for protectors for a 30 amp cord?? I guess code enforcement should be called to every campground in the US to check for the "approved" protectors, people like you make posting questions and having a useful conversation on this website impossible! I should have ignored you, since if you argue with idiots it is hard to tell the differance! Oh and please tell me again which walmart sells autoformers?

Carefully Spridle, these guys do not want to hear such things. Chris

this is the definitive answerer. You cannot safely connect a 30 amp #10 gauge cord to a 50 amp service using an adaptor without proper 30 amp protection. 2008 National Electrical Code NEC/NFPA 70 240.4.(D)(7). The adaptors from Wal-Mart and elsewhere are not protecting the 30 amp cords and are a violation of the NEC NFPA70. Yes they work but violate the National Electrical Code. You are simply skating on thin ice. Find a way to protect the cord with a 30 amp maximum 120 volt or greater fuse or circuit breaker directly after the adaptor. This is a simple engineering rule. No unprotected or under-protected wiring. Protection goes ahead of the wiring not after.

The thread that just will not die!

What he ^^^ said.

However. Put one meter lead in the 3 o'clock hole and the other in 9 o'clock and you will read 240V, there are two hot legs and are opposite phases.

If they were the same phase then you would read zero votes. That is not however how they are wired as it would double the current on the neutral, overloading that single wire.

Chris

Hi Coach-man;

You don't get a single Volts reading from a 50A receptacle. There are two 120 Volt circuits, one at the 9 O'clock and the Other at 3 O'clock. You measure each separately to Neutral(6 O'clock).

It is likely that one of the 50A legs was 90V.

Now, back to your 50A -> 30A pigtail question. I use one whenever I can. I also use a 30A -> 20A.

However,it is wrong to do so by the book. The long answer, which I already explained but you have not grasped yet, is that circuit breakers protect downstream wiring. The 30A cable going into your RV is upstream from the 30A breaker. Technically, that cable is unprotected by the 50A breaker.

HTH;
John

Coach-man wrote:

Well I for one are confused, we are talking about an RV plugged into a distribution panel, but you quote house wiring, that is not what I am talking about, to be specific, I am talking about the wiring after the circuit breakers in the distribution panel. I have seen voltage on the 30 amp side as low as 90 volts, with hot to touch 30 amp plugs. At the same time, plugged into a 50 amp plug the volts were 109. My current rig is a 50 amp service, on my previous class c it was 30 amps, I always plugged into a 50 amp plug where available with an adaptor, and never had a problem. You are quoting theoretical "what should be", when in fact not all parks are wired that way, they cut conners, talk about understanding the basics, alway check before plugging your RV in to ensure that the recepticle is wired correctly! My autoformer will tell me before I plug in!
We all should take a deep breath and relax, again the original question was "can I plug a 30 amp Rv into a 50 amp outlet"? Your drawings and descriptions of all sorts of wiring diagrams do nothing to answer that question! A statement was made about the advantage of using a 50 amp plug with adaptor rather than using a 30 amp plug directly, if you disagree with that then fine, disagree and we will agree to disagree!

If everything is working correctly, that is outlet, pigtails to breaker, breakers and box buss bars you will not see any difference, except with the possibility that the leg the 30 amp outlet is on is overloaded and when you switch to the 50 amp outlet and adapter and you ended up on the other leg which was not overloaded.

It is just how electricity works. The theory of electrical flow is how it actually occurs in the wild!

If you experience a hot plug of cord, then there is a problem with the plug or outlet it is plugged into, or the amount of current being drawn.

Chris

Me Again wrote:

Coach-man wrote:
The original question was can I plug a 30 amp RV into a 50 amp outlet, the answer was yes with an adaptor! Someone, mentioned that, that was dangerous, it is not, in fact several posts indicated that is was less likely to have a problem, brownouts, triped circuit breakers, etc by plugging into the 50 amp outlet, too which I agreed. At least one person disagreed and went into an esoteric discussion on wiring, and that it was the same regardless of which plug was used. I disagreed and continue to disagree! A "50 amp" plug is actually 100 amps total, that is two 120 volt 50 amp feeds with a common neutral. You can get real close to overloading a 30 amp circuit, but you have more cushion, with a 50 in a rig designed for 30 amp service. If there is a problem, your main circuit breaker in the rig would blow long before your pedistal breaker would go, and no you can not draw more than the maximum of 30 amps, and in a 30 amp rig with adaptor there is no way of seeing 240 volts in your rig! Even in a 50 amp rig, 240 volts to your equipment would be unlikely due to the fourth lead, ie ground!

So much misinformation in a single post. I brown out in the park power will be the same if you are plugged into a 30amp breaker or a 50 amp breaker with an adapter. The source on the 30 amp breaker and the 50 breaker are the same buss in the power pole. The breakers clip onto the same exact buss. To keep the neutral balanced on each power run through sections of the park, the 30 amp breakers are alternated on the two power phase busses. In a perfect world the neutral has little to no current flow back to the source, as the two phases cancel out.

BTW loose neutral when you have a 30 amp service just kills you power. This happen two days in a row while we were in Hemet in January and Golden Village Palms RV resort. I watched and talked to the maintenance guys while they repaired it. The first day they miss the neutral buss problem. Quote from them: "Be glad you are not a 50 amp coach/trailer!" My friend that was two sites over and who we stopped to see, said last week a guy burned up all the stuff in this MH! Duh!

More cushion on a 50 breaker. I 30 amp breaker is a 30 breaker, the one in trailer will not let you have more cushion!

Fourth lead?? The ground and neutral are not common in the trailers wiring. The ground is there to protect you, and you better not connect it to the neutral in the trailer. They are separate back to the main distribution panel.

"in a 30 amp rig with adaptor there is no way of seeing 240 volts" This is the only true statement you made.

We are all here to learn and people with both 30 and 50 rigs will read these posts.

http://en.wikipedia.org/wiki/Brownout_%28electricity%29

Chris

Well I for one are confused, we are talking about an RV plugged into a distribution panel, but you quote house wiring, that is not what I am talking about, to be specific, I am talking about the wiring after the circuit breakers in the distribution panel. I have seen voltage on the 30 amp side as low as 90 volts, with hot to touch 30 amp plugs. At the same time, plugged into a 50 amp plug the volts were 109. My current rig is a 50 amp service, on my previous class c it was 30 amps, I always plugged into a 50 amp plug where available with an adaptor, and never had a problem. You are quoting theoretical "what should be", when in fact not all parks are wired that way, they cut conners, talk about understanding the basics, alway check before plugging your RV in to ensure that the recepticle is wired correctly! My autoformer will tell me before I plug in!
We all should take a deep breath and relax, again the original question was "can I plug a 30 amp Rv into a 50 amp outlet"? Your drawings and descriptions of all sorts of wiring diagrams do nothing to answer that question! A statement was made about the advantage of using a 50 amp plug with adaptor rather than using a 30 amp plug directly, if you disagree with that then fine, disagree and we will agree to disagree!

Coach-man wrote:


Well which is it? Are they the same or differant? I double checked my calculations online with NEC, and stand by their minimum requirements, none the less you have already contradicted yourself, the lack of knowledge about how electricity works makes you wonder!

The purpose of a circuit breaker is to protect the wire/circuit downstream by breaking the circuit.

If you plug a 100A device into a 20A socket, the wire/circuit between the breaker and the device will be protected because the breaker will trip.

Now, on the instream side of the breaker you could have 2Ga wire where that wire is protected upstream by a breaker designed to protect much higher Amps.

HTH;
John