Question Marine 30 Amp Plug

[MFJ]

So I have a question I wanted to run by this group. A few weeks ago my wife and I traded in for a new trailer. This one's a step up from our old pop-up, but except for the sewage uses all the same connections. At least I thought it did. We're planning on a trip next week so I took a generator and water hose out to run everything on the trailer to make sure there were no surprises. Everything went fine, but I noticed something with the power connection to the trailer.

Some googling told me that my trailer uses a NEMA L5-30 plug, where the old trailer used a traditional NEMA TT-30 one. Basically these:

I was worried I had to buy all new power cords, but no the one it came with has a TT-30 male and L5-30 female, so I can still plug it in at any campground no problem (and don't have to waste more money). Everything I've read basically has these two plugs rated for the same voltage and amperage, which is where my question is. Why would they design a trailer with this plug? Is there some sort of advantage that I'm unaware of?

 

[Joe Hogan]

From what I understand these plugs perform the same task and can be interchangeable for a RV and other static (low movement) applications.

I believe for marine application the locking feature of the L5-30 is to keep boat movement (tides, waves, wakes, etc.) from working the connection loose. A TT30 would not be reliable, probably dangerous, for marine applications.

 

[MFJ]

Which makes me wonder why have it on a trailer at all? Especially if almost all RV 30 amp connections use the TT-30.

 

[Richpatty]

I had a twist on connector on a 2007 gas motorhome years ago, but it plugged into the post just the same (mine was 50amp). It should come with the power cord.

This only applies to where it connects to your camper.

 

[Kevin D Pem]

The reason boats use a twist lock on the boat side is!!! The powered cord will not fall in the water so an unsuspecting swimmer is not killed.

The same idea applies with an RV that has a detachable cord. Stepping in into a puddle could be quite shocking!!!