What's with all the 30A plugs and how to tell someone what I need?

Sorry I'm new to larger rvs (only pop-ups before) and I just don't get it.

My rv says it's running 125v 30A. No problem right? Someone said it's the same plug as a dryer (It's not! But I already knew that  ) So I tried to look up ther plug online to show them a picture. Type in "30A plug" and.... nope, those aren't really it. So I type in "rv 30A plug" and.... nope, those aren't really it either. Ok, um, let's try "125v 30A" well.... that's better, at least SOME of them seem right. What's going on?  So now I'm curious. How do I relate to others what plug I'm talking about. I decide to go to the local rv store and most of what "looked right" said "generator adapters". Wait, what?..... ok, back to the internet. (Now I'm on a mission) From what I have gathered, it's called a "twist lock", but even trying to research those there seems to be multiple diffrent kinds. I don't understand it.

Ok, I DO have the accessory I need (so I'm not looking for anything specific) and the veterans and electricians might laugh (or at least chuckle) at me (I know I am), but now I want to know. Why all the diffrent plugs? Even at the rv store (maybe it was a new employee) I had difficulty explaining what plug I had. She seemed to understand, but then kept bringing out the wrong one. Could the veterans here explain it to me a little better? I'm kind of worried now that when I go to a campsite, they will, of course, have the "other" type of rv plug (It seems to be more common), and I won't be able to plug in.

Am I crazy? (The answer is yes, but beside the point) But what the heck is going on here?

Here's a photo of both 30 and 50A receptacles.  They are, as far as I know, universal just about everywhere.  I've never seen another style of 30A plug intended for RVs, and if I did, I wouldn't want to connect to it without careful testing.

https://i.ytimg.com/vi/GoOR2AJGjOI/maxresdefault.jpg

When you're looking for the plug (male), it's a "NEMA TT-30P".  It is NOT a dryer plug.

Fun steak is correct. There are only 2 types of plugs. 30 amps is 120 volts 3 wire. 50 amps is 240 volts 4 wire. The twist lock you are referring to is 2 different ones also and they are on the RV end of the cord. Same things 3 wire and 4 wire. You RV should have on it what is required unless someone has changed it. 30 amps #10 ga wire. 50 amps # 6 ga wire.

If you have a 120 volt 30 amp RV, the only adapter you're likely to need at any RV park in North America is 50 amp to 30 amp. A 20 amp to 30 amp adapter is also handy for plugging into standard 15/20 amp outlets at home. Both adapters are readily available in the RV section at Walmart or on Amazon. Oh, and the plug used on the park end of 30 amp RV power cords is a NEMA TT-30P (linked below). The 50/30 adapter is useful for those rare campsites that have a 50 amp outlet only, and the sometimes worn or broken 30 amp outlets where a 50 amp is also available. The adapter only uses one hot leg and the neutral of the 240 volt 50 amp outlet, so only 120 volts is supplied to your RV.

https://www.amazon.com/Camco-PowerGrip-Replacement-Durable-55245/dp/B000PGXQNC/

cavie said:

Fun steak is correct. There are only 2 types of plugs. 30 amps is 120 volts 3 wire. 50 amps is 240 volts 4 wire. The twist lock you are referring to is 2 different ones also and they are on the RV end of the cord. Same things 3 wire and 4 wire. You RV should have on it what is required unless someone has changed it. 30 amps #10 ga wire. 50 amps # 6 ga wire.

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Wrong again cavie. The is more than just the two types. I have had two different 30 amp configurations on two different RVs. There is the standard one that most 30 amp RVs use. And there is the twist lock kind.

SeilerBird said:

Wrong again cavie. The is more than just the two types. I have had two different 30 amp configurations on two different RVs. There is the standard one that most 30 amp RVs use. And there is the twist lock kind.

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Go back and read my post. It says the twist locks are on the RV end of the cord. They are NEVER on the ped end. If you want to get technical, Plugs are on the ped end and receptacles are on the RV end. )

Much of your quandary is the distinction between a "plug" and a "receptacle" (aka "outlet") and the purpose of it.  A "plug" is the male end (the one with the prongs), and the receptacle is the female end (the one with slots to receive the prongs on a plug).  The different orientation and shape of the prongs on a plug are intended to help prevent mistakes like plugging a 120v device into a 240v outlet, and also to provide extra function, e.g. latching the plug to the receptacle.

You were probably shown various different plugs and adapters because you didn't say what the plug was supposed to do.  The outlets on the side of an RV or a portable generator are typically a latching type, designed to prevent the cord from being accidentally knocked loose.  They require a matching plug to achieve the latching.  There are two different styles of those, adding to the confusion.  However, the outlet that is RV industry standard for 30A campsite power is NOT a latching type, just a simple 3-slot type known as TT30R (Travel Trailer 30A Receptacle).  It probably should have been a latch type, but those weren't common when the standard was chosen many decades ago and now compatibility dictates that it will not change.  There is a matching TT30P plug, i.e. the one on the outer end of your shore power cord.

Electricians and engineers know these different types and styles by their NEMA (Nat'l Electrical Manufacturer's Association) standard names, but RV owners and RV store clerks often are not versed in those. Here's a chart of the more common types found in homes, shops, RVs and campgrounds:
https://en.wikipedia.org/wiki/NEMA_connector#/media/File:NEMA_simplified_pins.svg

There are actually similar variants of 15A and 20A plugs & receptacles, but only a few of them are common in residential and office use, so you probably aren't aware of them.  Ever look at the wall outlets in a hospital room? You would probably be equally confused there.

So, what to ask for?  Depending on which end of the power cord you are talking about, you want 120v, 30A, either blade (the straight prongs) or "twist lock" (the curved prongs).  The blade type will be TT30P or TT30R and the twist-lock  type is probably L530P or L530R if it is 30A only.

jaunvie said:

Sorry I'm new to larger rvs (only pop-ups before) and I just don't get it.

My rv says it's running 125v 30A. No problem right? Someone said it's the same plug as a dryer (It's not! But I already knew that  ) So I tried to look up ther plug online to show them a picture. Type in "30A plug" and.... nope, those aren't really it. So I type in "rv 30A plug" and.... nope, those aren't really it either. Ok, um, let's try "125v 30A" well.... that's better, at least SOME of them seem right. What's going on?  So now I'm curious. How do I relate to others what plug I'm talking about. I decide to go to the local rv store and most of what "looked right" said "generator adapters". Wait, what?..... ok, back to the internet. (Now I'm on a mission) From what I have gathered, it's called a "twist lock", but even trying to research those there seems to be multiple diffrent kinds. I don't understand it.

Ok, I DO have the accessory I need (so I'm not looking for anything specific) and the veterans and electricians might laugh (or at least chuckle) at me (I know I am), but now I want to know. Why all the diffrent plugs? Even at the rv store (maybe it was a new employee) I had difficulty explaining what plug I had. She seemed to understand, but then kept bringing out the wrong one. Could the veterans here explain it to me a little better? I'm kind of worried now that when I go to a campsite, they will, of course, have the "other" type of rv plug (It seems to be more common), and I won't be able to plug in.

Am I crazy? (The answer is yes, but beside the point) But what the heck is going on here?

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If going to look for one at a store (walmart, RV outlet, etc) it might help to take a picture of it on your phone. That  might make it easier to match t up. 

skydivemark said:

If going to look for one at a store (walmart, RV outlet, etc) it might help to take a picture of it on your phone. That  might make it easier to match t up.

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Yeah, that's what I did. It didn't help too much. (I think it might have been the sales person, but they tried real hard)

Gary RV_Wizard said:

Electricians and engineers know these different types and styles by their NEMA (Nat'l Electrical Manufacturer's Association) standard names, but RV owners and RV store clerks often are not versed in those. Here's a chart of the more common types found in homes, shops, RVs and campgrounds:
https://en.wikipedia.org/wiki/NEMA_connector#/media/File:NEMA_simplified_pins.svg

There are actually similar variants of 15A and 20A plugs & receptacles, but only a few of them are common in residential and office use, so you probably aren't aware of them.  Ever look at the wall outlets in a hospital room? You would probably be equally confused there.

So, what to ask for?  Depending on which end of the power cord you are talking about, you want 120v, 30A, either blade (the straight prongs) or "twist lock" (the curved prongs).  The blade type will be TT30P or TT30R and the twist-lock  type is probably L530P or L530R if it is 30A only.

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Thanks, this is really what I was kind of looking for. First the technical (NEMA) should help when I need to look something up on the internet, then the Layman's (L530P or L530R) when I need something from the store.

Hopefully I won't need anything anymore. (like I said, I DID actually get what I needed eventually) But just for reference I wanted to post a couple photos. They are (hopefully in the right order)

#1 The cover with 125v 30A imprinted on it attached to the side of my TT
#2 The cover open with the prongs showing attached to the side of my TT
#3 The end of the extension cord I got that is connected to (#2) the TT
#4 The end of the extension cord I got that is connected to the Campground's power pole

I believe this will be all I need (I also have an adapter to plug into a household outlet) although I might get an adapter to plug into a 50A Campground power pole just in case.

Thanks for the responses. If anything looks wrong with what I've got set up Please let me know. I was just REALLY surprised when I kept getting the "wrong" 30A extension cord.

Ahh! I take it that you didn't get the detachable power cord that's normally included with a TT purchase. Not knowing that could contribute to some of our confusion...

NY_Dutch said:

Ahh! I take it that you didn't get the detachable power cord that's normally included with a TT purchase. Not knowing that could contribute to some of our confusion...

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Yeah, sorry. I was just surprised at how many different ones there were and how easy it was to get them mixed up. And I was looking for all the different type of adapters I might need. I like to be prepared for anything. I have everything I need now which makes me feel much more comfortable and prepared for anything  8)

) ) )

cavie said:

Go back and read my post. It says the twist locks are on the RV end of the cord. They are NEVER on the ped end. If you want to get technical, Plugs are on the ped end and receptacles are on the RV end. )

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This 30A twist lock PLUG is on the pedestal end of my RV shore power cord: https://hubbellcdn.com/prodimage300/WBP_HBL2311_PRODIMAGE_300.jpg

mel s said:

This 30A twist lock PLUG is on the pedestal end of my RV shore power cord: https://hubbellcdn.com/prodimage300/WBP_HBL2311_PRODIMAGE_300.jpg

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There are no north american RV park power pedestals that will accept that plug. The NEMA TT-30P mentioned above is the only plug that the park pedestals will accept for 30 amp power.

A 125V 30 amp twist lock power connector on the post is commonly used at marinas for boat docks, etc. and very rarely if ever seen at RV parks, though I have read about a few west coast RV parks starting to require twist lock cords.

mel s said:

This 30A twist lock PLUG is on the pedestal end of my RV shore power cord: https://hubbellcdn.com/prodimage300/WBP_HBL2311_PRODIMAGE_300.jpg

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That is a 30 amp 120 volt twist lock plug and should NOT be on the end of your RV cord. The factory did not send it that way.  Somebody made that to plug into a generator for boon docking. You should have a 3 prog plug on the end of your RV cord.

Isaac-1 said:

A 125V 30 amp twist lock power connector on the post is commonly used at marinas for boat docks, etc. and very rarely if ever seen at RV parks, though I have read about a few west coast RV parks starting to require twist lock cords.

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Isaac, any idea why the west coast parks would require a non-standard RV plug? The only real benefit I can see for the park is selling lots of adapters...

NY_Dutch said:

Isaac, any idea why the west coast parks would require a non-standard RV plug? The only real benefit I can see for the park is selling lots of adapters...

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The L5-30 is a better connector than the TT-30. Also, no possibility of forcing the wrong plug into it. Since it is s twist lock, less chance for getting pulled put partially and arcing, which damages both the plug & socket. Also, an L5-30 can?t be partially inserted. Full insert plus twist required to get power.

The plug and outlet are called. Strangely enought "TT-30"
Or if you want to draw it out "Travel Trailer 30" 

And if you have having an outlet installed make sure that the installer knows it is a 120 volt and make him prove it by use of a plug in meter (The two flat blades or better yet get a 15-30 adapter and a plug in meter and plug it in)

And the big reason for the above is to make sure the electrician does not install a similar looking 220 receptacle. It will fry your entire electrical system and some of your appliances! 

My engineer son thought I could plug my 30 amp motorhome into his Tesla receptacle.  It took some convincing before he agreed I was right.