#1 – Zero maintenance layout (2200 sq ft layout) – You can’t maintain a large layout by yourself #2 – DCC 8 amp boosters and welding engine wheels of the engine derails #3 – Track Cleaning – Never again! #4 – Reverse Loops – Using a toggle switch with DCC #5 – Not removing ties on flex track #6 – IDC connectors - #M scotch locks/Suitcase connectors for track wiring-NEVER #7 - The Rolling Stock Truck Tuner tool & why do you need one #8 – Soldering Track Joints #9 – Homasote Expansion vs Wood #10 – DCC and you have to modify the turnouts – YOU DON”T #11 – Homasote Cost – making a mess when cutting – You Don’t have to make dust when cutting
PLW the MRR Myth Busters – #2 - The Myth is:
You will weld your wheels to the rails if you run an 8 amp DCC Booster!
I have been running my layout with ONE (1) 8 amp command station for almost 5 years.
I wanted to see just how far I could pu***he system. I had OPTUDs (OP Till U Drop) about every 6 months for a while and would have anywhere between 30 to 40 operators. We would run 30 to 40 trains during the 12 hours session with 15 or so running at any one time.
The system worked great. But then again we were using mostly radio keypads and very few plugged ones. I have now split the layout into three large blocks, each using an 8 amp Booster only because I needed the extra power for all of the sound engines I have.
If the layout has been wired properly there will be almost no resistance in the system. Using # 12 stranded wire is the recommended minimum to accompli***his. If the Buss Wires are longer than 50 feet then # 10 or # 8 wire should be considered. This is only to reduce resistance.
The wire drops from the track should be every 3 feet and on all three ends of a turnout. The reason is to keep the track voltage where it needs to be and not rely on the metal jointer
It is basic math really.
12 volts times 8 amps will ONLY produce 96 watts. Thats like a 100 watt lightbulb which is about 400 degrees farenheit. Your skin melts at 300 degrees. Paper ignites at 451 degrees.
So fif the circuit breaker fails and the metal can melt at that temperaature then yes is it will melt. Otherwise it won’t.
Simple as that.
I, my control system and my (classified) pieces of powered rolling stock are very happy with DC, thank you. Especially since conversion would cost me several months’ income (not just model railroading budget.)
As for welding ANYTHING with track power, the most powerful transformer-rectifier set I ever encountered (on a now-defunct club) could have put 160 watts to a single point-if:
The breaker failed to fire.
There was nothing else in series to reduce the voltage, or in parallel to spread out the amperage.
My Weller soldering gun produces double that!
Nothing is impossible, but I think the Mythbusters would rate this one, “Busted.”
AH yes but how do you detect a short if the system is designed to deliver 8 amps and the short is slightly resistive so only 7 amps is drawn from the power supply?
You may not be able to literally melt wheels and track, but you can put nasty pits in either through repeated shorting with a full 8 amps It’s called electrical discharge machining and sometimes it’s done on purpose.
Photos have been posted of damaged equipment. Plus, if you have that kid of short INSIDE the shell, that’s plenty of heat to melt a palstic shell, even if i can;t melt the wheels.
Not to mention it’s STILL better to have multiple power districts at lower current, especially in smaller scales, not just to prevent damage, but to prevent operator frustration when the entire railroad shuts down.
Now talking about DC power supplies our club had a number of G Scalers and we would set up the track out in the parking lot behind the Club during our Autumn Leaf Festival in October each year.
It got to the point that we had 10 or 12 trains making loops in the parking lot and our small factory power paks were overheating. We built a number of transistor throttles and began using 10 amp battery chargers (which was like the hi-output power supplies that Aristo-Craft was selling. We still did not have enough power to run all of the trains as we just kept adding more each year.
We finally purchased an old Auto service portable battery charger that was designed to jump start big diesel tractor-trailer rigs. We then modified it by replacing the old selenium rectifiers with newer silicone diodes. The output was tested in excess of 100 amps at 25 volts - full output 12 volt high (the charger had 6 settings – 6 volt low/med/hi – 12 volt low/med/hi). All this battery charger now turned into a big power supply was doing was to feed the transistor throttles and each one of those powered one G Scale track loop. It is unbelievable the amount of power required when you triple head 3 SD40 type engines.
Had we kept going we were beginning to look for a Lincoln Arc Welder to rebuild into a 200 amp power supply. The only thing that was holding us up was that the Welder needed 240 input and we needed to stay with 120 volts!
Some of the situations I have been in as a member of a club for 20 years.
Well I must have the luckiest group of layout operators there is as now that I have added 2 additional 8 amp boosters to my layout (24 amps) and have my OPTUD’s (OP Till U Drop) 12 hour operations sessions and have 30 to 40 operators (of which half are totally new to my layout and DCC) are able to run turnouts way too many times and have yet to run into this so called hi resistance short that everyone seems to have experienced.
There must be a lot of junk engines on your layouts for having been melted down! I feel sorry for your losses but I would think that I would be a lot more careful watching the way I ran my equipment if I had all of those derailments.
I might actually begin to look my trackwork over and go through all of my cars and engines to make sure they were all in gauge and waited to NMRA spec.
Oh wait a minute I have already done this and have so few derailments that we all gather round to view it when one happens. And usually whoever does short out a section of the layout by running a turnout gets razed so bad that they never want do it again! ;-o
Just some experiences form 20 years as a model railroad club member and my own home layout for 5 years.
Well guys I will step in here and say Bob is right. I regularly operate on his layout during our bi-weekly operations at his layout. I have also participated on almost every OP till You Drop (8 hours +)at his layout he has had over the past three years. I would guess, total hours I have at OPTUD’s would be about 40 hours. And about 20 other bi-weekly operating sesions a year I attend and operate aprox. three hours each time. This is 60 hours a year for the past three years I have spent on his on his layout operating. Once about a year and a half ago we cleaned his track for him since there is so much. We have not cleaned it since!! Bob would be able to tell you pretty close to the exact amout of hours I have actually operated on his layout. By the way we average about 5-10 operaters each bi weekly sesion. Combine those hours!!!
At any rate I operate at any given time any locomotive I want any time. As do all the other operators. I have stuff with factory decoders and also with Digitrax decoders I have installed. I will not run junk!!! I normally operate two Atlas Dash 8 40Bs. Usuallly one with sound. Once and a while I run some Proto stuff. And I will say I am adicted to sound and cant not use it now. I like to bring sound units to his layout because the more we can task the layout on a bi-weekly operation the better research that Bob gains for flawless operations on an OPTUD with operators who mostly have never ran on the layout. You see some of use regulars will step back and alow the “visitors” to enjoy it since we are on it every other time. So not only is Bob running alot of trains with a dispatcher…alot of the operators at the time are new to the layout. So with even rookie opeators he has had flawless operations. I have been to other layouts where guys get so pissed off they walk away and leave and vow never to come back. I have at least 2 layouts I will not return to untill the owner gets it together!
This is the Myth I am trying to bust. Apparently EVERYONE here has a melted engine that on their layout from this supposed problem.
I would like to visit these layouts that can melt turnouts and engine wheels.
Wait A Minute one of our NMRA Div 11 group operators had a layout like that. Way back in 1986 or so he was running the Keller OnBoard analog system using a 10 amp power supply. And back then there was NONE – ZIP – ZERO type of circuit breaker to shut off the 10 amp supply.
And YES he did melt a lot of turnouts back then as I saw this myself – not some hearsay (as in the MYTH thing).
And WHY did this happen?
Because of operator lack of caring. They would run the turnouts because they could not pay attention OR really did not care. But it kept happening and the owner finally figured out a way to fix the problem. He ended up cutting the track about 2 inches behind the frog and made this section electrically dead. He then made everyone run 3 unit diesel lash-ups and had them wire the front and rear units together. So when they would hit the dead track at each turnout the rear engine would power the front engine through the dead turnout and then the front engine powered the rear engine through.
Kind of a dumb way to fix an operators lack of caring about their equipment, isn’t it!!!
But getting back to 2006 now!
And I will bet that these so called melted engines (and I really would like to see just how many there are) were caused by operators lack of attention due to running a switch!
I would love to be able to visit these so-called problem layouts and really look them over.
What do wanna bet that it is either Operator error or Improper layout construction or both?
I can’t say anyone’s ever welded an engine in my experience (and I’d say that’s rather impossible), but as I said elsewhere I have seen, with my own two eyes, a “slow” or high resistance short on my club’s DCC layout that took place at a turnout that heated up the rails to a high degree. It didn’t cause a massive failure or make the ties a puddle of plastic, but it did soften them enough so that the rail in question had to be spiked.
Obviously, this was a wiring error on our part. Once fixed, it never happened again, and has never happened anywhere else on the layout. But it did happen once. And I wonder what would have happened if I hadn’t found it when I did.
So, welding wheels to rail? Busted. Melting ties? Plausible.
Wether it is operator error runnign a switch or an complete accident - does it really matter? Insufficient wiring too - the ‘coin test’ involves laying the coin on the track - not pressing it down as hard as you can. If your breaker doesn’t trip - you have inadequate wiring and stand a good chance of being able to create a short that draws a significant amount of current without poppign any breakers anywhere. No, it’s not the fault of the 8 amp booster, but it’s still a high-current short.
If your track and wheels are all in guage and adjusted properly, the only place you SHOULD potentially get a short is through operator error in throwing switches.
I do not deny 99% of derailments probably don;t even result in a short - unless somethign keeps shoving to push linked metal wheels all the way across the track, nothign will happen. But it IS electrically possible to short out and have nearly full power going through the short without kicking out any circuit protection. Note I said it will not turn your loco into a slag pile. Put 100 watts of heat into the pickups of say an Athearna nd see if it doesn’t melt the plastic sideframe, or at least deform it. Have 7 amps go through the hair-fine wiring of a typical loco. SOMETHING will give, somewhere. Melt the entire shell? No - but look how many people have melted parts of them by not replacing the standard 12v bulbs with low current 1.5v bulbs and resistors, or at least enclosing the 12v bulbs in a brass tube. Those are FAR from 100 watt bulbs - so the whole idea that “oh that amount of short current times volts is less than 100 watt light bulb” is not a valid argument.
It’s not luck, it’s just not likely. But it CAN happen. The better you build your layout, the less likely it is to happen - always a good thing, No one likes derailments. Eliminate them and you eliminate the issue. But accidents happen.
Have you personally had this happen to you or to any one that you have personally know had it happen to them?
I am trying to get this so called I know someone that knows some ones brothers mothers sisters kid that had this happen to and I would like to find out some answers not hear-say!
This is how this so called Myth starts. It may have happened but did anyone really investigate the real cause or just say that it was because it was the 8amp or 10 amp booster that was the problem. Was the booster circuit breaker cause the problem or was it due to too small of buss wiring or too small or too few drop wires? And would a 5 amp system have kept this from happening?
If you don’t have first hand info then we can theorize all day at what could happen.
I on the other hand have had this happen and I saw it destroy the turnout so YES it can happen but then again the system was the old Keller OnBoard analogue command control system with NO circuit breaker, period! And I operated on this layout I am talking about many times.
So Yep it happens but I know why it happened and the problem was corrected by putting the Circuit breakers that Tony’s sold for a while for the Keller system, before he was into DCC.
Most DCC systems produce 14.5 or more volts, so the actual wattage is 116 or greater. Also, your analogy to a lightbulb is flawed. If your chain of reasoning there were correct, how would a 25-watt soldering iron heat to a high enough temperature to melt solder? Here are some of the specs for a Weller 60 watt solering station:
Input voltage: 120v
Output voltage: 24v
Power consumption: 60w
Temperature range: 350°F - 850°F
(177°C - 454°C)
Heating is based not only on how much power you put through something, but on the contact surface area or cross-sectional area of the part(s), too.
Brunton google ohms law. I didn’t make it up he did.
And I was just trying to show a point not reinvent physics. Hopefully someone has figured it out. High wattage produces heat. Is that simpler?
And what was that point? That anything through which 100 watts of power passes will melt if it’s melting point is less than 400 degrees?
Ohm’s Law does not directly apply when calculating heating in a wire or at a connection. To calculate the temperature increase due to power dissipation at a point (Ohm’s Law does not compute power) requires quite a bit of effort and time, to say the least, but essentially you’re looking for the power dissipation density, meaning the power being dissipated for a unit surface area. The more power being dissipated thorough a given area, the higher the temperature becomes in the dissipation area. So 100 watts dissipation through a pin point can indeed weld the pin to the contacted surface, because the power dissipation density is so high. But 100 watts being dissipated at a high-tension power line splice is of negligible effect, because the power dissipation density is low.
But you are missing the point - it is NOT just wattage. My 15 watt soldering iron I use for fine electronics gets hot enough to melt solder, foam, and plastic model shells. With a mere 15 watts! Does my 100 watt gun get hotter? Probably, but th ebig advantage is it can heat a larger area. Try soldering #12 bus wires with that 15-watter. Good luck. But for the 100 watt gun, no problem. Yet both generate enough heat to melt solder.
And usually whoever does short out a section of the layout by running a turnout gets razed so bad that they never want do it again! ;-o