suitcase connectors

3M Scotchlock connectors are not cheap,they have cheap imitations on the market. I found the best place to buy them at a somewhat reasonable price is at an electrical supply house.

I use two different sizes of Scotchlock connectors on the CCRY:
One is a 12-10 AWG / 18-14 AWG (part # is 567), that I use for tapping the
DCC buss for the rail power feeders. My buss is # 12 stranded copper and my feeders are mostly # 18, although I do have some smaller.
The other is a 14-18 AWG / 14/18 AWG (part # 560) that I use for either
tapping off a lighter, sub buss, or even splicing together the feeders for
either track power or DC accessory power.
I would think that even a smaller size would be available, but don't know that for a fact. On the other hand if you double over (possibly even more than once) your lighter feeders before inserting them into the suitcase...it will work just fine.
Regarding how often a feeder is needed: My rule of thumb is to have a feeder placed at every connecting rail (that would be six rail joiners with feeders soldered to them) of a turnout and on every other section of flextrack.

Radio Shack has them. Don't know the p/n off hand.

Mike in Tulsa
BNSF Cherokee Sub

Ah, the infamous suitcase connector (also known as an insulation displacement connector, or IDC) again!

You'll find people here who swear by them, and others who swear at them.

I guess I'm in the latter category. No way will I use those things on my layout - they're too prone to developing conductivity problems. The blade also bites into the through wire, causing a high point-stress and fatigue multiplier, resulting finally in a broken wire. There can also be galvanic corrosion problems between the blade and the wires.

IDCs may be convenient; they are not reliable.

Others here will say just the opposite. [^]

You can get these at any auto parts store, in bulk!

They come in 3 sizes & are colour coded.

Yellow - 10 - 12 AWG
Blue - 14 - 16 AWG
Red - 18 -22 AWG

Gordon

You will find the IDC's at good prices by the box in electric supply houses if you shop around a bit, or mail order. Like most stuff the prices vary widely, but the 3M ones work about the best.
I use them on my layout for the feed bus but do agree with Mark on mobile applications and won't use them for automotive applications as they can cause the wire to fracture when bounced down the road, and corrosion from road spray is an issue. J.R.

I get mine at Home Depot about six bucks for around 30 pieces. I have had these on my layout for about 14 months now and so far no problems. They certainly make connecting feeders and busses more convienient. I use the 14-16 g size (the blue ones). The ones I get at Home Depot are designed for heavy wire in both sides so I just double up (fold over) my 20 g feeder and slip it in and when it crimps it gives a good solid connection. I guess time will tell if these are worth the convienience. They are easy to remove all though they do leave a bite mark in the wire. I drop feeders about every 2-3 feet. I like to over build so if I did get a bad connection at some point I probably would never know it with all the extra feeders.
Terry][8D]

The 3M 'Suitcase' connectors have superior conductivity. They are used in the automotive 'aftermarket' industry for adding connections. I cannot think of a more corrosive/vibration intensive enviroment than a car going though the seasons! Buy good ones. The clones that I have seen at Home Depot or Radio Shack really are not good. And if they have the 3M IDC's, they are very high priced. I got mine via mail order theough Mouser. 12-20 cents each is a average price in 'bulk'. Also, there are several variaties. I use the # 517-905 connector. This allows you to connect a #18-22 track feeder to a bus wire that is anywhere from #14-18 gauge wire. The current price is 18 cents each in bags of 100($18.00/bag).
You want to get the correct type for the wire you are using. The incorrect size my cut deep inthe actual metal wire, or not cut deep enough for a good connection. Here is the web URL:

http://www.mouser.com/


Jim Bernier

I've had them corrode in an automotive environment. They are commonly used in aftermarket radio installs and for trailer wiring harnesses. I've seen them melt due to heat build up caused by resistance cause by corrosion. This was on my truck a year after a "professional" trailer hitch installation. I fixed the problem by splicing and soldering.

Best advice, stay away from the suitcase connector.

The automotive industry views these connectors as amateur hour. No reputable shop or Professional Technician will touch them. Some of the guys call them “comeback locks” instead of scotch locks. The only aftermarket installers who use these are the “quickie” alarm, remote starter, trailer hitch and radio installers. These shops employ inexperienced, entry-level installers whose main goal in life is to get the job out the door, fast. It takes a while but then the vehicle ends up back at the dealer or quality independent electrical shop for the proper repair. Then the consumer pays twice. Any shop that uses these is a good one to avoid.

Even when used in under dash applications, which are high and dry, low vibration, low current circuits they fail. They do not fracture or corrode. They simply stop conducting current. A close inspection may show arching due to the excessive resistance that developed. Underhood and underbody is an even bigger joke to due to water intrusion and vibration.

One of the many problems with them is the tiny contact area compared to other means of connections. This results in a voltage drop across the connector, which increases over time. Lets compare contact areas: 0.040 for the IDCs vs. 0.125 - 0.500 for other methods like soldering, wire nuts and crimps. Soldering and wire nuts are direct wire-to-wire contact. Crimping makes a much tighter and larger connection than IDCs.

One analogy often used to explain the flow of electricity is water. Imagine if someone takes a 1/2 hose and pinches it down to 1/16 or so. You will see a definite drop in volume of water due to the restriction. The same thing happens in electrical circuits when you have poor connections. This is the effect that IDCs have on a circuit over time. Unless you have a DMM and measure voltage drop, you will not know this.

There is one good thing about them. They can be excellent diagnostic aids. When you end up having a problem, you can be 99% sure the open is at the connector with just a visual. Look in any auto service manual or training course. You will never see these used for any type of splice or repair. Trust me, I have authored enough manuals, and repaired enough electrical problems to know.

It’s funny to hear of people who worry about soldering rails, rail joiners, rail feeders, and jumpers to prevent voltage loss and then use these connectors.

Jim

If the temptation to use suitcase connectors strikes, grab a big club and beat it to death immediately!

There are three ways to connect wires that work, last and do not come back to haunt the installer: Solder, screw terminals (with appropriate stake-on connectors if using stranded wire) and wire nuts. Anything else is a problem waiting to happen.

Chuck.

QUOTE: Originally posted by Brunton Ah, the infamous suitcase connector (also known as an insulation displacement connector, or IDC) again! You'll find people here who swear by them, and others who swear at them. I guess I'm in the latter category. No way will I use those things on my layout - they're too prone to developing conductivity problems. The blade also bites into the through wire, causing a high point-stress and fatigue multiplier, resulting finally in a broken wire. There can also be galvanic corrosion problems between the blade and the wires. IDCs may be convenient; they are not reliable. Others here will say just the opposite. [^]

Mark:

Do you come by this information from personal experience or from listening to others who likewise don't like suitcase connectors?

I ask because I have used them extensively on my Siskiyou Line and I have not had a single failure in 10 years of use. Not one failure - none - nada.

If they are all that bad, they should have gone off the market long ago along with all the other failed inventions.

My neighbor works for the phone company and they use the waterproof gell version of the IDCs all the time to do phone line repairs. He says the suitcase version we all know and love is a similar concept only without the waterproof gell added.

I think what it really comes down to is personal preference, rather than a long line of failed wiring that used these connectors. [swg]

The IDC connectors will work for a while but in an environment where moisture and humidity is high (basements – garages) they begin to cause problems.

We used them on our club Lionel display (located in an old basement) and had the trackwork up for almost 10 years. We had use #12 stranded buss wires and #12 drop wires. The track we used was Gargraves and most of the #12 drop wires were soldered to the rails. The IDC connectors were used to connect the drops to the buss wires. We had the proper Scotckloc connector for #12 wire and they worked well for 5 years.

We then began to notice that the trains would slow down on certain sections of track and were not sure why. An inspection of the wiring showed nothing wrong and in the process of checking the wiring the problems seemed to go away. While this was OK it did not really explain why the problems even showed up.

Then a different section of track began giving problems. We had the layout set up blocks using industrial toggle switches and it was designed to be able to have 2 different transformers available to run any given section of track. So the transformers were not the problem as either one would not make the track run any better. It got so bad at the last we had to have the bad sections set on the other transformer set to a higher voltage just to keep the trains moving at the same speed section to section.

Then on the forums someone stated that the potential problems existed where the metal blades came in contact with the wire and very minute amounts of corrosion would form on the IDCs. This then explained why when we did our wiring inspections we seemed to correct the power loss but had not actually done anything except moving the wires around. By moving the wires we must have made good contact again by somehow breaking through the corrosion. I really could not see any of this in any of the connectors but then it probably was that very small amount.

We subsequently rebuilt the Lionel display at our club and we are NOT using the IDC connectors PERIOD ! We are soldering all connections.

BOB H – Clarion, PA

cmr:

Good, some real-life experience!

I'm at 10 years on the layout so it sounds like I may need to watch for failures to perhaps start. And it sounds like the suitcase connectors make a connection that has a useful life of about a decade. I wonder if 3M has any such data ...

Guys, I use these and they work great:



I have recommended these on this forum in several threads. Try 'em, you'll like 'em.

Here's the link so you can see it better than the image above:

http://www.posi-lock.com/NewFiles/posi-tap_n2_a.jpg

Joe

I think the real problem here is the humidity. Any open joint (as in 2 wires twister together) will work for a while! But after a while the copper will oxidize and the joint WILL become a high resistance connection.

You may not have a problem if the room is kept to a low humidity value! But in our application we did not want to run a dehumidifier all of the time when no one was at the club. So our problems began to show up.

Just some additional thoughts!

BOB H – Clarion, PA

Why not cover up the open joints with a bit of die-electric grease?

This should take care of the moisture problem shouldn't it?

It's used regualrly in automotive situations, again a high humidity area.

GORDON

Do what you want BUT when things start to act strange and you can’t seem to figure out what is wrong, don’t start complaining

Just think about the junk IDC connectors.

You were warned!

We at the Club believed the hype (BS) and we lived to regret it BIG time!

And I know we all believe every word a car salesman tells us don’t we!!!!

BOB H – Clarion, PA

You know, I'm tired of trying to warm people not to use them. I'm done trying. Let the people who say they are great just go ahead and help the users a few months later when the layout starts acting up. They must own 3M stock they way they carry on telling us, who know that they are not good, that WE are just too stupid to use the superior product of 3m properly. I'm done trying.

Scotch locks, by all means use them! Fred

I guess the point here is that there is no perfect wire tap solution. All the solder junkies out there would like folks to think that it's the best, and quite frankly, it's not. Stripping wire in the middle of a run is always fun. And soldering above your head under the layout is dangerous, slow, and difficult. Sure, it may result in a semipermanent electrical bond, but botched solder jobs are also possible. And then you have the interesting possibilites of under the layout shorts when two solder joints come into contact with each other...unless you goop each joint with a liquid rubber. No thanks.

Using terminal strips is also not a perfect solution. They can be pricey. If you don't use crimps, then wrapping the wire around them is pain. If you do use crimps, they can work loose if abused, and the screws themselves can also loosen over time. You also have to have a place to put them, access to them, and have many of them.

Even these Posi-taps I have questions about. For example, do you have to strip the tapped wire, or does it pierce the insulation? Secondly, I have to question their advertising when they state in their ad (posted above) that "no tools (are) needed"...and yet step #3 tells you to strip the tap wire. Huh? I don't know about you, but I find that I need some kind of wire stripper to strip wire (IOW, a "tool"). What do they want us to use? Our teeth?

Scotch-loks have their problems, as seen above. I would not use them in any kind of vibration area with any exposure to water, salt, or other corrosive elements. However, my club gets them for about 7 cents a piece, and our layout is in an environment where it doesn't get above 80 degrees or below 60, and humidity is kept low through the use of two industrial dehumidifiers and the A/C. In our specific situation, they work extremely well, and we've used hundreds of them over the past 5 or 6 years. In our case, we always try to use two drop wires for each block, which means that we'd have to have two failures on one block before we'd notice any problems...

Paul A. Cutler III
*****************
Weather Or No Go New Haven
*****************

This suitcase connector debate will go one forever just as what is the BEST (insert subject name here)!

Now those that state about soldering overhead is a problem, it can be! The easiest way I have found is to use the smallest diameter solder and have a good hot soldering gun (150 to 250 watts) (not a soldering pencil – 40 w). This will heat the joint fast and the solder will melt fast.

Also I made most of the Buss wire able to be pulled out from under the layout or at least to edge of the layout. To do this easily I used metal conduit clamps screwed to the underside of the layout. They will leave a small opening so that you can slide the Buss wires out and then bring them out to the edge or drop them down to solder the drop wires to them.

A lot of my benchwork is narrow enough that the Buss wires can be run on the front of the layout and a valance then covers up the Buss wire once all of the wiring is done.

I also use hand ground throws so I do not have to put any other wiring in place (which keeps the rats nest to minimum)!

As for keeping the soldered spots from touching each other without taping or insulating them, When I made my Buss wire pairs I taped them together every 18” or so with a wrap or two of colored electrical tape. What this does is keep the two Buss wires in a neat cable and then when I need to solder a drop wire I just use one of the grip type wire strippers to go in and slide the insulation back.

Now these spots are separated by 1 to 2 inches. I wrap the drop wires around the appropriate Buss wire and solder the drop wires. There is no way the 2 drop wires can ever touch each other as the electrical tape is holding the Buss wires together!

The heat from the soldering process will expand the insulation back together and usually (If you have a neat joint) will only leave a very small area of bare wire exposed!

BOB H – Clarion, PA

QUOTE: Originally posted by jfugate QUOTE: Originally posted by Brunton Ah, the infamous suitcase connector (also known as an insulation displacement connector, or IDC) again! ..... Mark: Do you come by this information from personal experience or from listening to others who likewise don't like suitcase connectors? I ask because I have used them extensively on my Siskiyou Line and I have not had a single failure in 10 years of use. Not one failure - none - nada. If they are all that bad, they should have gone off the market long ago along with all the other failed inventions. My neighbor works for the phone company and they use the waterproof gell version of the IDCs all the time to do phone line repairs. He says the suitcase version we all know and love is a similar concept only without the waterproof gell added. I think what it really comes down to is personal preference, rather than a long line of failed wiring that used these connectors. [swg]

Sorry it took so long to answer, Joe.

My answer is both personal experience plus listening to others, with a dash of professional knowledge thrown into the mix.

I've never used them on my layout - my experiences have been primarily in automotive use, where I've had "professional" installers add trailer light wiring and stereo equipment using IDCs. All gave trouble after time, because of the suitcases.

I've also asked of some of the avionics and other electrical engineering folks I've worked with over the years about IDCs. None had any good things to say about them. No place I've ever worked (aerospace industry) has allowed their use, whether in the aircraft, spacecraft, or in the ground support equipment (hydraulic carts, portable electrical power carts, etc.).

The part about galvanic cororsion is from professional experience unrelated to the IDCs themselves - two different conductive materials in contact ALWAYS forms a connection that can be succeptible to galvanic corrosion to some extent. How succeptible depends on how dissimilar the materials are that are in contact.

The water-proof phone company IDCs probably eliminates most galvanic corrosion problems (since water can't get to the joint and act as an electrolyte), and I'll bet their use is strictly controlled. The phone company has all sorts of special stuff made for them that isn't generally available - their IDCs may be one of them. I'm sure they're very specific about how and when the IDCs can be used. Ask your neighbor how much training he had to go through, and what the actual procedure is, to install them.

If you don't experience problems with your IDCs, then maybe you have "the touch," and your layout environs are not conducive to corrosion.

Anyway, I hope that answers your questions, Joe. No personal model railroading experience since I won't use them on my layout, but experience and technical knowledge of other applications, and the mechanics of how they operate.

I need to get updated on the newest things that are going on in the model railroading world... maybe just start over completly because I don't know much of the terminology and the newest things in model railroading (especially DCC)

QUOTE: Originally posted by Paul3 Even these Posi-taps I have questions about. For example, do you have to strip the tapped wire, or does it pierce the insulation? Secondly, I have to question their advertising when they state in their ad (posted above) that "no tools (are) needed"...and yet step #3 tells you to strip the tap wire. Huh? I don't know about you, but I find that I need some kind of wire stripper to strip wire (IOW, a "tool"). What do they want us to use? Our teeth? Paul A. Cutler III ***************** Weather Or No Go New Haven *****************

Paul, the wire that you tap into, i.e. a 12 gauge bus does not get stripped, you are correct, it is pierced when the bottom two pieces of the Posi-Tap are screwed together. The smaller gauge wire, i.e. a 20 gauge feeder, does require stripping. You are also correct that a wire stripper tool is needed, but for the feeders only.

I think it is a reasonable expectation that a wire stripper is implicit in any wiring type activity. I think Posi-Tap was looking more at not requiring soldering tools, clamps, etc.[;)]

One reason that the telecommunications industry can use the scotchlocks is the typical current draw on your phone line is only between 0.025 - 0.045 milliamps. Their installers are also out in the elements where soldering or crimping; along with tape or shrink wrapping may not be practical. Water intrusion is probably their main concern.

An alternative to the method that Bob H suggests for those who do not want to solder is to use what is keeping your home wiring intact - wire nuts. They come in a variety of sizes, can be used to connect different sizes / types of wires together and are economical. Serviceability is excellent because you can back probe one to check for voltage with out disconnecting or stripping the tape off. Very reliable. When was the last time you had an open/short/corrosion problem in your home wiring?

The connector Mastiffdog has suggested will work fine. Note the SAE testing done on it. The only tool required is a stripper; you also need a tool for the scotchlocks as well. I have not used one but have heard good feedback about the Posi-Taps. I do not think anyone will start calling them “comeback taps”.

There are other automotive connectors that will work as well, the crimp/solderless types. This type of method is dependent on the use of a good quality crimping tool. I do not mean the Wal- or K mart types. One thing to be aware of is they can only be used one time, which may or may not be problem.

Prior to getting into service engineering, I was an ASE Master Auto Technician for 20 years. I made a great deal of money repairing bad connections from other folk’s vehicles and the scotchlocks were a big part of that. I also belong to a professional forum. The scotchlocks have been discussed many times. I have not heard one person defend them for any 12v application. Our electrical lab has never used them for any type of testing, stationary or road.

Jim

I've had suitcase connectors on my switching layout for the past 6 years with no problems. Keep in mind that my train room is in an outbuilding on my grandmother's farm. No climate control means the layout has to deal with temperature extremes--below zero, and above 100 F is common, along with humidity changes. The only problem I have is keeping the track clean.

I got a bag of the gel-filled connectors from a neighbor who works for the phone company. He used them when he connected my DSL line and there have been no problems. I have never had a problem with them in my basement layout. I have had problems with wirenuts. And I have been burned while soldering overhead. Nothing is perfect for everyone.

QUOTE: Mark: Do you come by this information from personal experience or from listening to others who likewise don't like suitcase connectors? I ask because I have used them extensively on my Siskiyou Line and I have not had a single failure in 10 years of use. Not one failure - none - nada. If they are all that bad, they should have gone off the market long ago along with all the other failed inventions. My neighbor works for the phone company and they use the waterproof gell version of the IDCs all the time to do phone line repairs. He says the suitcase version we all know and love is a similar concept only without the waterproof gell added. I think what it really comes down to is personal preference, rather than a long line of failed wiring that used these connectors. [swg]

My experiences are the same as Joe's. Mine have been in place for nearly five years with no problems whatsoever. By the way, I also solder every rail joiner and have power feeders every 3 to 4 feet. When dealing with 12-gauge bus wires, I find them particularly useful. I respect the opinions of those who have had trouble with them, but in my case, I hardily recommend them.

If I begin to have problems in another 10 years, I'll be the first to admit my mistake. I'll just be happy to have survived the bird flu. [;)]

QUOTE: Originally posted by cmrproducts This suitcase connector debate will go one forever just as what is the BEST (insert subject name here)! Now those that state about soldering overhead is a problem, it can be! The easiest way I have found is to use the smallest diameter solder and have a good hot soldering gun (150 to 250 watts) (not a soldering pencil – 40 w). This will heat the joint fast and the solder will melt fast. BOB H – Clarion, PA

Properly installed, Suitcase connectors will probably work just fine (he said never having used them on his layout). I have had them fail often when used in automotive situations. The only thing that I have had more problems with with automotive wiring is the crimp on connectors! I personally prefer to use soldered joints and or Terminal strips.

I avoid soldering over my head with a passion! I worked for a couple summers for the Telephone Company (Rochester, NY) about the time the suitcase connectors were first coming out. I have gotten a couple of bad burns from being careless with soldering irons and having molten solder fall on bare skin. I have no intention of losing an eye or badly burning myself by soldering under the layout. Amost all connections on my layout do involve soldering as I really don't think the suitcase connectors really are that good....... I use terminal strips for connections to my bus systems (DCC and DC) Wires connecting stuff are connected to the terminal strip with spade lugs. These are first crimped and then soldered. (Why? take that "solidly" crimped wire - spade lug and twist it a few times. I will usually fall off in your hand!) All soldering is done at the workbench and then installed under the layout. I do not strip any wires in the middle. Wires are cut and connected to terminal strips, and then connected to the next one and so forth. I also use both a main bus and several sub buses and then connect to the track for DCC. It looks more like a spider web. This provides the shortest run to get power to any spot on the layout.

Now, before several of you tell me what an idiot I am to do this, It works well for me, and I have some sound reasons for doing it this way. You can wire your layout any way you want......... (you don't have to like or agree with the way I do my wireing!)

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