Socket to me…
Some random notes about installing the electrical, and well, sockets. Three prong sockets have got to be as common as dirt, but they are not all the same as I discovered, and not all kinds are available at every home improvement store. Mostly the seem to vary in terms of how you hook up the wires. The cheapest ones just have screws, which is fine if you have solid wires because you can just bend the wire around the screw and tighten it down. I will assume that if you are wiring an RV you are using stranded wire, and possibly many fairly fine strands at that. Wrapping those around a screw just doesn’t work.
One solution is to use crimp on lugs, and for the ground terminal, or screw, that is often the only choice. Crimp on lugs work fine if you have the right tools and know what you are doing. You can solder them after crimping if you must, but do not tin the wire and then crimp it. That will make a high resistance or unreliable joint.
Use ring lugs of the appropriate size, not fork lugs. Fork lugs have a tendency to spread and work loose, and should only be used in applications where the fork is captured to prevent spreading, like a bus bar. A ring lug can’t work loose, as it is fully trapped under the screw head. Ground screws and ring lugs are a problem though because the ground screw (often tinted green) is not meant to be fully unscrewed. They smash the last thread or two to prevent them from unscrewing and falling out. You can unscrew them though, it just takes some extra force. A good socket driver makes the job easier.
Some sockets, and switches ect. for that matter, have a plate under the screw head that pulls down on the wire. Avoid those if you can. They can work with stranded wire, but they don’t always work well. The wire strands tend to get out from under the plate and the whole thing can work loose. Pull test all your connections regardless of the socket type, just to be safe.
Some sockets have a hole in the back that you insert the wire into. They also have a screw and plate on the inside. In this case the screw pulls the plate towards the screw head and clamps down on the wire. These are the best I have found for stranded wire. They are not perfect though. Depending on the specific socket the hole for the wire can be rather small. It can be difficult to get a 12 GA stranded wire into that hole without a few strands bunching up. Truth be told, I had a few loose strands here and there that I ended up clipping off. One or two tiny strands won’t reduce the current carrying capacity much, and you don’t want them touching something that they shouldn’t be touching.
Some sockets have a hole in the back that look just like the ones you want, except that they have a spring clip arrangement that grabs the wire. They might work great for solid wire, but they are unusable for stranded wire. You have to push the wire in past the spring clip and stranded wire won’t be pushed without fraying all over the place.
GFI sockets have some similar issues, except that they are larger and leave even less room for the wire inside a small handi-box. I know of no solution except to keep the wires fairly short and then use whatever swear words you like best while putting them into the box. Just make sure you don’t pull any wires out of the socket while forcing it into the box.
Wire nuts are also a special challenge with stranded wire. By “wire nut” I mean the twist on cup like connector that has a spiral cone or spring inside. They are convenient, and they do work, but I have found that it is easy to end up with at least one wire into the nut that is not very secure. Mostly I try to avoid them by designing the wiring so that all the sockets are in a series chain. That way you can use the screw clamps that are part of the sockets to make the connections.
Sometimes you have a junction point where 3 or 4 wires come together with no socket. I try to avoid 4 wires coming together in one wire nut, and I pretty much never do 5. It is just too difficult to get all the wires twisted together with full and even contact and then get the wire nut on. Regardless of what you do, pull test everything to make sure you don’t have a wire hanging on by a strand or two. I know I found one bad connection that way. It could easily have gotten hot and started a fire.
The problem with stranded wire and wire nuts applies to the DC wiring as well. I soldered a flying lead onto some connections and then used a wire nut to make the final connection in the box. Crimp on spade lugs with the mating socket lug are another good option. My experience is that they work well, but don’t use them on a connection that you intend to connect and disconnect often. Once fully connected they can be a real bear to get apart again.
I find that crimp on lugs have marginal strain relief where the insulated wire comes out. Some of the really fancy ones have built in shrink tubing with what amounts to hot melt glue inside. They seal up really nice but are expensive and not always available at your local home improvement store. I find this is another terrific use for Goop. A little dab around the back of the crimp lug will seal the joint and dry to provide a compliant strain relief. Of course there is always regular shrink tubing as well.
To be continued….
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