Anyone make a decent 30 amp RV plug (NEMA TT-30)?

belfert · July 18, 2011, 06:12:06 AM

Does any company make a decent 30 amp NEMA TT-30 trailer plug? (Plug, not receptacle) I need to put a plug on the end of a 10 AWG cable. I'm used to how nice the NEMA locking plugs are. The stripped wire just goes straight in and a little plate gets screwed down to hold the wire.

I have a Cooper NEMA TT-30 plug and it is a piece of junk. It uses screw terminals and you have to twist the wire around the screws. The problem is that the cable is stranded wire and it is near impossible get all the strands under the screw for a good connection.

I bought a used Marinco 50' 30 amp cable with L5-30 plugs on each end for less than just the wire alone would cost. My bus has a 30 amp RV buddy plug that I want to plug into. I cut off one end of the Marinco cable so I could put on the RV plug. In hindsight I should have left the L5-30 plug on there and just installed an L5-30 receptacle on the bus.

Sean · July 18, 2011, 06:39:52 AM

The Camco "Power Grip" model, available at Camping World and elsewhere, is probably the best you can get. These are the yellow ones with the built-in "handle." Camco also makes a plain one, black, without the handle.

I have not seen a TT-30 with the type of terminal you describe. Those, BTW, are not limited to locking plugs, nor do all locking plugs have them. For example, HD and Lowes carry a 5-15P with those terminals.

Your best bet for dealing with the screw terminals and fine strand wire, such as found in SO and SJ cable types, is to crimp high quality ring terminals on the wire ends, then put those under the screws. If you don't want to fully remove the screws, which are often slightly staked to make them somewhat "captive," then use bent-nose spade terminals instead. For most plug housings, you will probably need to use uninsulated terminals for them to fit.

-Sean
http://OurOdyssey.BlogSpot.com

belfert · July 18, 2011, 07:29:40 AM

The Camco plug wasn't one I found in my research. I'll see if one of the two local RV places has one. It is a 60 mile round trip to the local Camping World. I thought about terminals, but I didn't think they would fit with the current plug.

I already have some L5-30 male plugs I got for free so I may still go that direction.

bevans6 · July 18, 2011, 07:51:36 AM

amazon has them in stock, you could get them to ship it to you, probably have it tomorrow.

http://www.amazon.com/Camco-55245-PowerGrip-Replacement-Plug/dp/B000PGXQNC/ref=pd_rhf_shvl_1

Thanks for pointing out I had the wrong link!

Brian

belfert · July 18, 2011, 12:59:45 PM

I saw them at Amazon, but I didn't want to pay for expedited shipping since I don't have Prime. A local RV repair place that is pretty close by normally stocks them, but they are out and will have more tomorrow. He said they sold 3 or 4 on Saturday.

I'm still strongly thinking about just putting an L5-30 receptacle on the bus and putting an L5-30 plug on this line. I have the L5-30 plug. I was only using the NEMA TT-30 plug since I had it on hand and the bus has the receptacle. I don't think this line will ever be used at a campground.

artvonne · July 20, 2011, 04:01:03 AM

You can tin the stranded wire ends with solder and then bend them round the terminals for a decent connection.

Menards often has decent plugs, another source is Franks RV up in Ramsey. I avoid CW like the plague.

belfert · July 20, 2011, 05:07:50 AM

I ended up getting the Camco Powergrip plug at a place called Mike's LP that isn't far from home. Much closer than Camping World. I checked Menards, but they don't carry the NEMA TT-30 plug. They do have the receptacle.

The Powergrip plug still has screw terminals, but at least the blades aren't loose and there is lots of room for the wire. My plan is to stop at the hardware store tonight for some terminals to put on the wire.

Sean · July 20, 2011, 10:12:56 AM

Quote from: artvonne on July 20, 2011, 04:01:03 AM
You can tin the stranded wire ends with solder and then bend them round the terminals for a decent connection.

I strongly advise against this practice.

Soft solder such as that commonly used for electronics or plumbing has a very low melting point, which is, after all, why it is used in the first place. The connections we are talking about here are routinely called upon to carry very high currents, and it is not uncommon for terminals on RV power plugs to reach temperatures well in excess of 200°F. While that's not quite hot enough to completely liquefy solder, it is most definitely enough to soften it to the point where the compression on the terminal will relax. That, in turn, will increase the resistance, leading to even more heating, which will soften the solder even further.

The ultimate result of this process will be at a minimum a poorer connection to shore power, with increased resistance in the plug. More likely, it will lead to melted plugs, charred terminals, or even a short.

Screw-tension terminals on power plugs are meant for mechanical connections only. I recommend you either mechanically secure the bare wire, or, if a better connection is desired, use a mechanically crimped quality copper terminal on the wire, in turn mechanically secured to the terminal.

To give you some sense of the temperatures involved in these connections and what they can do, here is a photo of a 30-amp adapter that was in normal use for three weeks -- carrying only 20 amps continuously. The cord was hanging upside-down (the receptacle was installed that way) and you can see the blades have melted right through the plastic:

(I wrote about this incident in this blog post: http://ourodyssey.blogspot.com/2011/07/relaxing-on-clinch.html)

-Sean
http://OurOdyssey.BlogSpot.com

bevans6 · July 20, 2011, 11:38:16 AM

Coincidentally I just installed a couple of extension cord ends a little while ago. The screw terminals had captured and formed square washers to place the stranded wire under. I was able to get pretty clean and neat connections using just the stranded wire under the terminal. I saw the same thing when i replaced the ends on a 7 pin trailer connector. Isn't that sort of connection the standard for stranded wire? They worked really well for me once I got the stripped length just right.

Brian

belfert · July 20, 2011, 12:04:27 PM

Quote from: bevans6 on July 20, 2011, 11:38:16 AM
Coincidentally I just installed a couple of extension cord ends a little while ago. The screw terminals had captured and formed square washers to place the stranded wire under. I was able to get pretty clean and neat connections using just the stranded wire under the terminal. I saw the same thing when i replaced the ends on a 7 pin trailer connector. Isn't that sort of connection the standard for stranded wire? They worked really well for me once I got the stripped length just right.

No, not standard on all types of plugs and receptacles. I'm used to using this type of connection, but all of the NEMA TT-30 plugs I have found to date just use screws. You're in Canada so perhaps standards are a little different there.

bevans6 · July 20, 2011, 01:24:04 PM

Thanks, I wondered why the fuss. I can't remember the last time I had a 120 vac or 240 vac rated plug that I was installing that didn't have those little square washers. They have crimped sides and capture the stranded wire really well. I didn't realize that when you said 'screw terminal' you meant just a simple screw head terminal!

Brian

belfert · July 20, 2011, 05:43:16 PM

Here is a picture I took of the internals of the plug. It doesn't show the screw terminals all that well. I did pick up some forked terminals to crimp on the wires.

artvonne · July 20, 2011, 09:45:20 PM

In all seriousness, any RV 30 amp plug that would overheat at 30 amps to the point of failure, is very poor quality. To do that on a 20 amp draw is simply detestable. IMHO, no electrical service cords, plugs or receptacles should ever get so hot you cant handly them. If they do, you have, or will soon have a problem.

That said, the few 30 amp plugs ive found at Menards had the socket type connection terminals that the screw squeezes the wire into. Wrapping wire round screws is for low amp wire. Funny its even UL rated, must be China

Sean · July 20, 2011, 10:33:22 PM

Quote from: artvonne on July 20, 2011, 09:45:20 PM
In all seriousness, any RV 30 amp plug that would overheat at 30 amps to the point of failure, is very poor quality. To do that on a 20 amp draw is simply detestable. IMHO, no electrical service cords, plugs or receptacles should ever get so hot you cant handly them.

I submit that you don't get around much. Any TT-30 plug can overheat due to a constant draw of 20-30 amps in hot weather. I see these failures all the time, both on RVs and on boats. All it takes is a bit of a loose tang in the receptacle -- and you, as the guy with the plug, have almost no control over the receptacle, which belongs to the campground/repair shop/Elks lodge/whomever. Sure, a low-quality plug can contribute to the problem, but I can show you spec-grade Hubbell plugs that have melted cases due to electrical heating. So, no, it does not mean the plug was poor quality.

More than once I've had to disassemble campground pedestals to fix poor wiring in the pedestal that was either overheating my cord, or tripping the breakers:
http://ourodyssey.blogspot.com/2007/08/my-turn-to-catch-up-on-photos.html

The conditions under which the tangs on these plugs heat up to the point of being almost too hot to touch are actually fairly common and I do not consider "normal" ohmic heating of the plug, by itself, to be a problem. But it's definitely not a place to use solder, either on the wire ends or on a terminal.

-Sean
http://OurOdyssey.BlogSpot.com

artvonne · July 20, 2011, 10:50:40 PM

Been plugging in the RV all over the south for over 15 years without any trouble. But likely not with the frequency of you or others.

In any case, if youve seen that multiple times your right about solder.