Is it possible that the broken strands have been pulled farther than the blade width apart over time, thereby increasing the voltage drop across the break. Also depending on the IDC used, I have noted multiple strands (4-5) broken when I took the connector apart (I was curious how many strands got broken). I also measured the resistance across and found nothing at time of install (i understand not the same thing as voltage drop).
BMMECNYCIs it possible that the broken strands have been pulled farther than the blade width apart over time, thereby increasing the voltage drop across the break. Also depending on the IDC used, I have noted multiple strands (4-5) broken when I took the connector apart
I'm sure both of those things could work against the IDC. But my numbers are already stacked against the IDC. I'm sure it would take several strands to reduce the effective gauge from 12 to 16. I'd also guess some of the nicks are bridged by the blade. There are probably some that don't break any. Very few of us run a bus at 5 amps also.
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
dknelson I really do dread the experience of soldering while under the layout looking up -- and yeah suitcase connectors sure looked and look like a tempting alternative. I am reminded of an article decades ago in RMC (or just possibly the NMRA Bulletin) -- enough decades ago that I cannot seem to find it -- where the guy did all his wiring connections on terminal strips screwed to things that looked a bit like ping pong paddles or pizza slabs with a flat surface and a handle, and the stranded wire was all left loose enough that he could (gently) pull out the paddle and redo or review the connections and the wiring in the best light and working from above not below. He also thoroughly mapped out and labled everything on that "paddle." The more I think about it the more I think he made his own terminal strips using parallel lines of brass screws. Like I said it was an article from a long time ago .... does it ring any bells with anyone? I'd like to re-read it if I could find it. Dave Nelson
I really do dread the experience of soldering while under the layout looking up -- and yeah suitcase connectors sure looked and look like a tempting alternative. I am reminded of an article decades ago in RMC (or just possibly the NMRA Bulletin) -- enough decades ago that I cannot seem to find it -- where the guy did all his wiring connections on terminal strips screwed to things that looked a bit like ping pong paddles or pizza slabs with a flat surface and a handle, and the stranded wire was all left loose enough that he could (gently) pull out the paddle and redo or review the connections and the wiring in the best light and working from above not below. He also thoroughly mapped out and labled everything on that "paddle." The more I think about it the more I think he made his own terminal strips using parallel lines of brass screws. Like I said it was an article from a long time ago .... does it ring any bells with anyone? I'd like to re-read it if I could find it.
Dave Nelson
No paddle, but I use hinged boards that swing down to work on them then up out of sight when I'm done.
Dave
Lackawanna Route of the Phoebe Snow
First you tell us cheap DMMs cannot measure voltage drop which is laughable.
Then you mention that the ohm reading does not go low enought on your meter to meausure voltage drop, while the rest of the world knows the ohms scale measures resistance.
And now you are telling us that it would take
carl425So you would need 16,667 IDC's to create a 1-volt drop.
Wow
Jim
The effect of all the nicks is going to be cumulative. Unless you are super lucky and get each IDC on so it cuts the same strand every single time. Yes it will take a lot of strands cut to get a #12 wire down to a #16 - but that also depends on the wire being used. If there are 50 strands making up that #12 wire, it will take more IDCs then if there were 10 strands, since each strand is a bigger part of the whole.
And distance matters - remember the OP had a bus run of over 100 feet (didn;t sound intentional, but sort of the way it worked out and no one caught it until there were problems) - so it actually worked fine for some period of time before the long term reliability of the connectors caused enough of a drop to be an actual problem.
And yes, the same thing would happen to water pipes. If you keps breaking a 4" pipe with sections of 3" pipe, at the end you may have the same volume of water but the pressure is going to be low. It works in reverse too - something I need to consider for my house, which I guess I am lucky that at least it's all copper, as is my wiring, given it was built in the early 70's when copper was ridiclously priced. I have very small water feed lines to my sinks and showers and so forth, and as such the pressure is less than ideal. The verticals in the walls would be a huge project to rip out and replace, however there are some who run bigger pipe from the source up to where the vertical starts. WHile there is still a restriction on the end, reducing the majority of the restriction helps raise the available pressure. It's like taking a 50 foot run of #18 wire, and replacing 45 feet of it with #12. Voltage drop goes down.
My fancy desktop meter has a conductance measure, and in informal tests, it can tell the difference between a couple of fet of #12 wire and connecting the meter to the ends of a nearly full spool of the same #12 wire. I don;t know how accurate it is, a fancy meter like this needs to be calibrated and I don;t own calibration equipment, nor do i do anything precision enough to really require it (I only have this expensive fancy meter because I got it for free - all I've been buying lately are the cheap HF meters, which are plenty adequate).
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Soo Line fanFirst you tell us cheap DMMs cannot measure voltage drop which is laughable.
No, I said they can't measure the voltage drop induced in a bus by a single IDC.
Soo Line fanThen you mention that the ohm reading does not go low enought on your meter to meausure voltage drop, while the rest of the world knows the ohms scale measures resistance.
No, I was merely taking a shortcut. We know it is resistance that causes voltage drop. It is easier to measure the resistance and calculate the voltage drop.
I showed you my math, show me yours. At least offer something to substantiate your claims other than more claims - and now personal attacks.
The OP has a long bus on a large layout with many IDC's. He said up front that he saw no drop on the bus other than what you would expect from the length/gauge.
Carl,
Math is only usefull when all the variables are known. When trouble shooting, the excessive resistance value is unknown. So plugging numbers into a online calculator will not tell you how much or where it is.
In Jims example, he found several areas of excessive drop. One across a circuit braker and another at a IDC. While the wire resistance is constant @ a known voltage and @ a known load, every connection, broken strand, loose terminal, over crushed crimp, etc all add resistance. And the values do not apprear in a online calculator.
That is why measurements are taken, to turn unknowns into knowns. How can you quanify the total ciruit resistance value of a circuit when these variables are present? One strand or 4 strands ?, a nick .003 or .004? What if he used different brands of IDCs?
Soo Line fanThat is why measurements are taken, to turn unknowns into knowns.
I'm sure there are folks that would argue both sides of the math vs measurements question. The simple fact however is that you have offered neither to support your assertion that IDC's will cause a significant voltage drop in a bus.
Now Boys!
I am an Electrician and we tried suitcase connectors years ago on automobile and trailer wiring. They were no good then and they are no good now. Certainly, the wet and corrosive environment caused failures sooner on trailers than on our layouts, but the fact remains suitcase connections are not very good.
The Buchannan wire nuts are hard to beat. And if filled with silicon or sealant they are even excellent in damp locations.
NP 2626 "Northern Pacific, really terrific"
Northern Pacific Railway Historical Association: http://www.nprha.org/
I can only imagine how bad IDCs would be on a trailer, especially a boat trailer that gets submerged when launching or recovering the boat. Doubly so for one used in salt water. I'll stick to soldering, thanks.
The worst suitcase connectors might still be superior to my soldering
rrinkerI can only imagine how bad IDCs would be on a trailer, especially a boat trailer that gets submerged when launching or recovering the boat. Doubly so for one used in salt water. I'll stick to soldering, thanks.
You need the IDC the phone company used to repair my buried phone line about 25 years ago.
This thing was a tupperware-type box about 4x3x1 with the IDC blades right in the center. The rest of the box was filled with something that looked like axle grease. They put the wires in the blades, closed the box, and buried it. I switched to FIOS years ago, but it was still working then.
It's the grease/silicone - keeps all moisture out, prevents the joint between the blade and the wire from corroding over time. SOunds more like a 66 block than anything - used in phone closests adn stuff, without the sealing enclosure around them, you do occasionally need to repunch wires as the connections deteriorate.
Thanks folks,
When I converted my layout from DC to DCC, I kept the old wiring with blocks, etc. Although it works fine, I planned to rewire the layout to comply with DCC wiring practices.
Few months ago I bought wires and a full bag of IDC "Suitcase" connectors. After reading this thread, I decided to leave those connectors alone and to go with soldering.
Guy
Modeling CNR in the 50's
Use Posi-taps instead, FAA approved and fairly cheap bought in bulk. Dose not cut any wire and can be reused if needed.
Still have one problem - like Scotchloks, they don't have a size that fits my use - #20 track feeds, with a #12 bus run.
The web site doesn't show it very well, but I assume there is a notch all the way to the open side of the run connection, so you can slip one of these on in the middle of a wire run and not thread it on from the end.
rrinkerThe web site doesn't show it very well, but I assume there is a notch all the way to the open side of the run connection, so you can slip one of these on in the middle of a wire run and not thread it on from the end. --Randy
That is correct:
A voltage drop video for scotchlocks:
Could it be the connections naturally oxidize over time as they are exposed to the air? Oxidized connections don't conduct as well. And if the metals between the IDC and the wire are different, an oxidation is bound to occur.
Soldered connections are different in they aren't exposed to an atmosphere which would promote oxidation.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
rrinkerStill have one problem - like Scotchloks, they don't have a size that fits my use - #20 track feeds, with a #12 bus run.
I can't say for sure, but it looks to me like only the bus size is important and they will work with most any size drops.
But I can say for sure that those things are really expensive. Over a dollar per tap. For that price, you could get somebody to come to your house and solder them for you.
DigitalGriffinCould it be the connections naturally oxidize over time as they are exposed to the air? Oxidized connections don't conduct as well. And if the metals between the IDC and the wire are different, an oxidation is bound to occur.
Don,
3Ms other connectors, which are made from the same material do not have the same issues. So if oxidation were to blame, I would expect it to happen on other connectors.
For example, I've seen their automotive spade, bullet and barrel types last forever when used in under dash applications.The inside of a car is subjected to extreme temperature swings. Its not unreasonable in northern parts of the US and in Canada to have lows near 0 F.
Within a short time, the cabin temperature can rise to 80F, a 80 degree delta. In southern climates, a similar condition happens with the use of A/C.After the car is parked, another hot/cold soak occurs and the process repeats, many thousands of times over the life of the car.
However, rarely do I see a connector, OEM or aftermarket, fail unless it is a IDC.
In a sense, those spade connectors might be somewhat self-cleaning, since as they expand and contract due to temperature variances, the tab is going to slide in the channels. Just a wacky theory.
Working in the electronic OEM world, our company incorporates a lot of mass IDC type connectors in our products, i.e. ribbon cable connectors and harnesses, with really no documented failures due to age. I just asked one of our engineers regarding this topic, and besides from initial assembly errors, he hasn't seen any problems...and this is with 28AWG 7 strand ribbon cable carrying low voltage/amperage. We also use a lot of individual IDC connectors with multiple poles for larger gauge wire without issue
Just saying.....
Chris M
Soo Line fan Don, 3Ms other connectors, which are made from the same material do not have the same issues. So if oxidation were to blame, I would expect it to happen on other connectors.
If you look at the build of the connector compared to the others, the kinds you listed have a very large attached surface area which helps "bind" the wire and keeps it from moving. Oxidation occurs on metal that becomes exposed to air. So if the bound wire is metal to metal with no air exposure, then the contact should last a very long time.The IDC does not have a tight fixed connection. It has a small contact area which does not really prevent the wire from twisting. I know I've grabbed IDC's and held a wire and seen them "twist" when tracing connections beneath a layout.
rrinker Still have one problem - like Scotchloks, they don't have a size that fits my use - #20 track feeds, with a #12 bus run. The web site doesn't show it very well, but I assume there is a notch all the way to the open side of the run connection, so you can slip one of these on in the middle of a wire run and not thread it on from the end. --Randy