Set Screw Wire Nut vs. Crimp

[gklott]

I've been looking for a small, vibration resistant UL-listed wire connector for 12 AWG stranded marine wire. Am installing the wire for the AC power system. Looking for a solution to connect 2, 3, or 4 conductors.

Everyone seems to shun away from Ideal In-Sure and even the better winged wire nuts.

From reading the specifications, the Ideal 30-222 set-screw wire connector seems like an excellent, robust solution, $0.75 ea.

Otherwise, the Ideal 2006S crimp connector with the Ideal 2007 nylon snap-on insulator would be a cheaper alternative, and about $0.40 ea.

However, to achieve the UL-listed condition, I would need to use something like the Ideal C24 Crimp Tool, which is about $60. I have a Klein Journeyman J1005, but it doesn't seem large enough. So the crimp connector might cost about the same.

Does anyone have experience using the set-screw connector? Which do you use?

73/gus

[perryg114]

Wire nuts are code as long as they are inside a closed box. They need to be twisted together. Never seen one fail if done right. If all wires are stranded the connection should be even better.

Perry

[GMFL]

I am in the electrical manufacturing business. And own a company that manufactures underwater lighting. In our manufacturing process we use butt crimps, but also use a Thomas & Betts crimp tool that cost about $400 which side supports the crimp and will not allow you to under crimp the connector. A properly done crimp will provide a great and safe connection. If you do buy a quality crimping tool you will have it forever so you will be able to use it on all your wiring projects. One like listed below would work great.

https://www.amazon.com/Thomas-Betts-.../dp/B00DWILMV8

[uncle_bob]

Hi

The only thing I would add to the "buy a good tool" recommendation is to be sure you get the correct crimps to go with the tool you buy. Unless you have some time to experiment, it's much easier to just use the T&B crimps with the T&B tool. Indeed you can use this or that tool with this or that connector. It will work for most combinations. For what ever reason, I have always found the "bad" combinations when doing mix and match ....

Bob

[SuzyHomemakr]

What about some sort of electrical box with a bus bar inside? Especially if you want to connect 4 leads together. Also, you might consider extra circuits if you have that many places to go.

[gklott]

Originally Posted by SuzyHomemakr

What about some sort of electrical box with a bus bar inside?

What box and bus bar do you recommend that is UL-listed? I am using the set-screw wire nuts inside a 4" x 4" x 1-1/2" D metal junction box with solid cover.

[gr.austin]

First of all wire nuts are NOT for mobile applications. Over time they will vibrate loose. MY A/C unit was wired with Wire Nuts from the factory. They other electrical connections were done with the approved crimp connections. My A/C stopped working after 2 years and I found burnt wires and wirenuts that fell of when I touched them. I changed to crimp terminals.

I have done some Laboratory testing with these connectors and have found that when properly done with the approved tool for the crimp barrel that this connection is the best available. The wire nut with the set screw will vibrate loose because the set screw puts too much force on the wire and the wire extrudes over time and becomes loose. Buy the right tool (make sure it is the tool supplied by the manufacture of the crimp barrel) a few thousands difference makes a big performance difference. Be safe not sorry...
Happy Streaming.....

[DavidsonOverlander]

What about solder and heat shrink tubing?

[Mollysdad]

Another vote for solder.

[Nuvite-F]

Originally Posted by gr.austin

First of all wire nuts are NOT for mobile applications. Over time they will vibrate loose. MY A/C unit was wired with Wire Nuts from the factory. They other electrical connections were done with the approved crimp connections. My A/C stopped working after 2 years and I found burnt wires and wirenuts that fell of when I touched them. I changed to crimp terminals. ..

While I will agree that wire nuts are not optimum for mobile applications, I think they have been getting a bum rap on Airforums recently.

Case in point, I have never had a wire nut connection fail in our 1980 Caravelle, which is full of wire nut connections and is now 37 years old and has God knows how many miles on it. For that matter, I never had a wire nut connection fail in our old 1960 Pacer, which is now 57 years old and the last time I heard, was still on the road.

Properly applied, wire nut connection seldom fail. Properly applied, crimp connections seldom fail. Improperly applied, either one will fail. There's no substitute for good workmanship. Your mileage may vary.

[uncle_bob]

Originally Posted by Nuvite-F

While I will agree that wire nuts are not optimum for mobile applications, I think they have been getting a bum rap on Airforums recently.

Case in point, I have never had a wire nut connection fail in our 1980 Caravelle, which is full of wire nut connections and is now 37 years old and has God knows how many miles on it. For that matter, I never had a wire nut connection fail in our old 1960 Pacer, which is now 57 years old and the last time I heard, was still on the road.

Properly applied, wire nut connection seldom fail. Properly applied, crimp connections seldom fail. Improperly applied, either one will fail. There's no substitute for good workmanship. Your mileage may vary.

Hi

For that matter, an improperly done solder joint will fail in stranded wire. You need strain relief .... if it's not there, you can have a problem. It's true on a missile system (oopss !!), it's true in an RV.

Bob

[55AS]

All the 110 wiring in both my 55 Flying Cloud and 67 Overlander was connected with wire nuts. No signs of failure in any of them after 50-60 years...

[lewster]

As a matter of 'standards', the RV industry came about as an off-shoot of the home industry (used to be called 'house cars or house trailers' and took much of their plumbing and electrical standards from the residential home building industry.....HUGE MISTAKE!!!!!

The MARINE INDUSTRY is where the RV folks should be looking for standards, as RVs have way more in common with water craft than a house that doesn't move!

The ABYC (American Boat and Yacht Council) develops the standards used in the boating industry with safety and potential fire mitigation as the main concern. As such, proper crimping IS the designated wire connection standard. In addition, the use of solid conductors (ROMEX) and wire nuts in ANY APPLICATION is strictly forbidden by ABYC.

I follow all of the ABYC E-11 and other applicable standards in all of my work, as this is assurance that the installations fully comply with all of the ABYC standards.

This level of application might not be required by RVIA, but it IS required by ME....and I'm the one ultimately responsible for what I do.......and I really, really like to sleep at night after completing any electrical modifications or installations.

What works for you is great (wire nuts, ROMEX, etc) ........ but what is required of me far exceeds what simply 'works'.

[Boxite]

The marine industry is certainly a good guide. The aviation industry is even better, IMO.

Aircraft do not use "wire nuts". In answer to Davidsons question... soldered connections in stranded wire is also not good because vibration will set up a stress-riser at the end of the soldered joint and it will fail at that point. Aircraft specifically call for crimped butt-joint, etc. connectors.

(Marine and aircraft wire is also a better product...in most marine, and all aircraft stranded wire, each individual strand is "tinned" before being assembled into the conductor, which reduces corrosion. The connectors are also not the common butt-splices you find down at most auto-supply houses, ... but are higher-quality and also pre-tinned to avoid electrolysis.)

There's nothing I hate more than an electrical problem I've already worked on...failing again! The slight increase in cost of quality materials and methods far outweigh the frustration of continuing problems.

[DavidsonOverlander]

Originally Posted by lewster

As a matter of 'standards', the RV industry came about as an off-shoot of the home industry (used to be called 'house cars or house trailers' and took much of their plumbing and electrical standards from the residential home building industry.....HUGE MISTAKE!!!!!

The MARINE INDUSTRY is where the RV folks should be looking for standards, as RVs have way more in common with water craft than a house that doesn't move!

The ABYC (American Boat and Yacht Council) develops the standards used in the boating industry with safety and potential fire mitigation as the main concern. As such, proper crimping IS the designated wire connection standard. In addition, the use of solid conductors (ROMEX) and wire nuts in ANY APPLICATION is strictly forbidden by ABYC.

I follow all of the ABYC E-11 and other applicable standards in all of my work, as this is assurance that the installations fully comply with all of the ABYC standards.

This level of application might not be required by RVIA, but it IS required by ME....and I'm the one ultimately responsible for what I do.......and I really, really like to sleep at night after completing any electrical modifications or installations.

What works for you is great (wire nuts, ROMEX, etc) ........ but what is required of me far exceeds what simply 'works'.

Is there a way to view these standards without paying the annual fee to join the American Boat and Yacht Council?

[uncle_bob]

Hi

If the "travel home" industry had decided to use aviation or marine build standards, methods, and certifications, our trailers would be priced more like a similar (cabin) sized plane or yacht. For me, that's simply out of the price range.

If you want to avoid wire nuts, go with proper crimps and a proper tool ...Yes, it's an expensive step up (see comment above ...)

Bob

[SuzyHomemakr]

Originally Posted by DavidsonOverlander

Is there a way to view these standards without paying the annual fee to join the American Boat and Yacht Council?

The "bible" on the subject is "Boatowners Mechanical and Electrical Manual" by Nigel Calder. Still in print, after all these years!

I think that the real problem lies in hybrid systems that tack on to the existing wiring in the trailer. If you're stripping the trailer down to the frame, absolutely go with stranded wire and ABYC standards. The main AC problems that I've had is trying to get romex to work with terminals, and trying to gang together a bunch of wires with wire nuts.

As to the first, when I was attaching the romex leads to my Blue Sea main panel, I had leads pull loose . So my fix, which seems to be holding, is to attach the ring terminal with Crimping Electrical Pliers (https://goo.gl/fhy1n5), then put a tiny bit of solder just at the ring end of the terminal.

As to the second problem, I'm getting by on wire nuts, but don't really like it. One of the great things about wiring the trailer yourself is that you can set up easy ways to troubleshoot or add on to the system. You can set up the greatest wiring ever, then ruin everything with a stray screw or cut. If the electrical is broken up with shorter hops from place to place, you can troubleshoot much easier, and replace wire easier. Of course, that means more possible points of failure. <sigh>

Anyway, I've found these Stud Junction Boxes (https://goo.gl/orG1kU) that I haven't used, but they sure look nice. Insulated, orderly, easy to set up strain relief, easy to label what goes where, and to visually inspect if problems arise. Could be the perfect solution!

[uncle_bob]

Hi

I guess this is worth going into in a bit more detail:

When you use solder on stranded wire a couple of things happen. Some matter more on small wires:

1) Part of the wire *dissolves* into the solder. If you cross section the wire, the copper that is left "necks down" right where the solder joint starts. This weakens the wire right at the joint.

2) You turn stranded wire into solid wire. It goes from flexible (due to the strands) to stiff (because it is solid). This is very obvious with fine strand speaker wire or welding cable.

3) You use some sort of flux on the joint. It may be applied manually or it may be buried in the solder it's self. Without flux, solder does not work well. Some of the flux will be left at the joint, buried in the strands. Regardless of the claims made by Mr Flux Inc, the stuff is not good to leave on wires.

4) Unless you do soldering fairly often, getting the joint right with modern (lead free) solders is a bit tricky. You need the right tools and practice. They also are less forgiving of 40 year old oxide on a wire. A bad solder joint is not going to help you much. Yes, you could use lead solder. You might get a hassle if you ultimately sell the trailer.

All of these things create a weak point right at the place the wire goes from flexible to rigid. Throw in vibration and the wire *will* break at the joint. Yes, I have reams of test data on this. I also have spend a lot of "quality time" working out how to prevent it in places that solder had to be used. If you have a choice, avoid solder unless you have good strain relief. That's provided there is vibration in the environment. In a home or lab application, it's not a big deal.

Bob

[prairieschooner]

Solder creates a "hard spot" that may cause wire fatigue.
Wire Nuts tear the strands especially with Marine Grade Wire because it is much thinner than most others.
Wire Nuts with a Set Screw are even worse at tearing the strands.
If you want to connect multiple conductors try a Terminal Strip. If it is for Positive conductors you could just provide a cover to protect from accidental contact.

[Ruscal]

During my lifetime I've used about every type of connection available. I have seen examples of all of them fail. They all have their ups and downs regarding suitability of purpose. Convenience and speed are desirable by most people, so you see a lot of crimped connections. At a young age I purchased a large Belden crimp terminal set with tool. It was very handy and I purchased 2 more to carry in vehicles. These got a lot of use for hooking up trailer connectors, a car audio, ham radio gear etc. I did see some failures of the joints produced with that tool. Some from not tight enough crimp, some from wire shear. I saw a demonstration of an aerospace crimping tool that was very impressive. It swaged inward uniformly instead of just 2 sides. You could not pull the wire out of the connector when held in a vise. That is an ideal connection, but it had to have the connector and wire size exactly matched to function. Out in the real non aerospace world things aren't matched. You have all wire gauges on a vehicle, and only 3 gauge sizes in a Belden set. So we improvise by using the smallest connector that the wires will fit into and squeeze that tool for all we're worth. Then you do the pull test and sometimes the wire or wires will pull out. If they don't you deem it OK and move on. That simple crimping tool has it's limitations. It doesn't leave you with a warm fuzzy feeling. I have seen more failed crimp connections than any other kind on vehicles.
Those Scotch squeeze with pliers type connectors used for making "T" taps are convenient also, but I have seen many failure with those also.
Over the years I have only seen 2 cases of soldered wires failed due to shear at the edge of the joint. Both were on the rear of trucks with the wires not supported at all. They were blowin in the wind and floppin about.
A soldered joint is preferred by me when I want reliability and low resistance. It is not convenient, takes more time to prep, and 2 electric tools to accomplish. High quality shrink tube is part of the equation in support of that shear point where the solder and wire strands meet. When the wires are loomed and supported they don't fail on street vehicles. I am told by off road racers that solder doesn't work for them. I have no experience there.

One thing to try on AC wiring on trailers may be to add 3:1 adhesive lined heat shrink over properly connected wire nuts to vibration proof the connection. It may not be NEC approved, but would keep the nut from turning, and would be easy and compact.
Russ