Sorry, Internet Explorer suddenly blinked out and flashed and dissappeared. I had not even hit post yet. Then there were three identical posts.
Current x Voltage = Power
14 Amps x 110 Volts ~= 1540 Watts for microwave oven
0.5 Amp x 4 Volts ~= 2 Watts for HO peddler freight
4 Amps x 6 Volts ~= 24 Watts for heavy drag freight
25 Amps x 10 Volts ~= 250 Watts for really big model railroad
Current ² x resistance = Power Loss
4 Amps ² x .0045 ohm/ft x 40' x 2 = 6 Watts power lost in long #18 wires
4 Amps ² x .075 ohm/ft x 10' x 2 = 24 Watts power lost in long code 70 rails
It is the second equation that can cause the problem for model railroads.
The high current through the slightly resistive wires and rail causes small voltage (power) losses so the trains don't see all the voltage or power. If the out and return wires are long, a loss of, say, 1.5 volts, then this may be very noticeable to the train, but not the microwave oven.
I operated on a friend's DCC layout and there were three places where trains would suddenly speed or slow. There were auto light bulbs (for current short protection) in the loop as well as the long wires, so part of the problem may have been differing bulbs. The builder was careful to use heavy wire and many feeder wires, but the different power blocks still were noticeable.
Another possible cause may have been some smaller wiring in the power routing circuitry for a group of switches.
Wow, just read most of the site you gave the link for, good stuff there. It reminded me of school, voltage, current, resistance,if I never have to figure out another combination circuit again, it will be too soon. All his work points to the fact that there is no electrical reason to go larger than #12 unless you have a staduim sized layout.
rrinker Pretty much anythign you could want to know about wiring with DCC is to be found on Allan Gartner's site: http://www.wiringfordcc.com//. He recently did a test of feeder sizes and lengths. There is plenty of overkill bandied about when it comes to DCC, but for argument's sake, if the maximum distance from a booster is 30 feet, you have 60 feet of wire total. #12 is probably overkill, but #18 is probably too light - at 2 amps, the #18 wire will drop .77 volt, probably noticeable. The same run with #14 wire and the same 2 amps would only drop .3 volt. Load the booster down all the way at 5 amps and the #18 will drop 1.9 volts - definitely too much. #14 even would drop .76 volt. #12 would be under a half volt, at .48 volt. Any of those wires is capable of carrying 5 amps without melting - it the resistance per foot and the voltage drop that matters most. --Randy I totally agree with what you said, it does'nt contradict what I said. Thats why I say #12 is the way to go because it includes a little room for voltage drop.
Pretty much anythign you could want to know about wiring with DCC is to be found on Allan Gartner's site: http://www.wiringfordcc.com//. He recently did a test of feeder sizes and lengths.
There is plenty of overkill bandied about when it comes to DCC, but for argument's sake, if the maximum distance from a booster is 30 feet, you have 60 feet of wire total. #12 is probably overkill, but #18 is probably too light - at 2 amps, the #18 wire will drop .77 volt, probably noticeable. The same run with #14 wire and the same 2 amps would only drop .3 volt. Load the booster down all the way at 5 amps and the #18 will drop 1.9 volts - definitely too much. #14 even would drop .76 volt. #12 would be under a half volt, at .48 volt. Any of those wires is capable of carrying 5 amps without melting - it the resistance per foot and the voltage drop that matters most.
--Randy
I totally agree with what you said, it does'nt contradict what I said. Thats why I say #12 is the way to go because it includes a little room for voltage drop.
considering the cost of wire, i don't see that trying to save a few cents ( maybe even bucks ) is worth the hassle. instead of the that should do approach, go the overkill way and have no worries.
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker What did he say that is trying to make you sound stupid? Martin is merely correcting a common misconception about wiring, namely that if #14 is good for 15 amps in you house wiring it is more then sufficient for 5 amps of DCC. Problem is, the issue with your layout isn;t the safe current carrying capacity of the wires, but the voltage drop. #18 wire is probably plenty to handle a 5 amp maximum current, however if you run 50 feet of it all around your layout you WILL see the train slow down as is gets farther from the point where the booster attaches, no matter how many feeders you put in. The wire won't melt, or make your benchwork catch on fire, it's working at well within its limits, but the voltage drop is what gets you. Long runs of too small a wire may also prevent your system's circuit breaker from tripping. The quarter test is actually a fairly reliable indicator of how good the wiring is. Set a quarter on the rails - do NOT press it down. Your circuit breaker should trip. If not, the wiring is inadequate. If the circuit breaker does not trip in such a situation, it's possible that it won't trip int he event of a derailment, and then you're looking at fried decoders. This has nothing to do with what brand of DCC system you chose to use. --Randy
What did he say that is trying to make you sound stupid? Martin is merely correcting a common misconception about wiring, namely that if #14 is good for 15 amps in you house wiring it is more then sufficient for 5 amps of DCC. Problem is, the issue with your layout isn;t the safe current carrying capacity of the wires, but the voltage drop. #18 wire is probably plenty to handle a 5 amp maximum current, however if you run 50 feet of it all around your layout you WILL see the train slow down as is gets farther from the point where the booster attaches, no matter how many feeders you put in. The wire won't melt, or make your benchwork catch on fire, it's working at well within its limits, but the voltage drop is what gets you. Long runs of too small a wire may also prevent your system's circuit breaker from tripping. The quarter test is actually a fairly reliable indicator of how good the wiring is. Set a quarter on the rails - do NOT press it down. Your circuit breaker should trip. If not, the wiring is inadequate. If the circuit breaker does not trip in such a situation, it's possible that it won't trip int he event of a derailment, and then you're looking at fried decoders.
This has nothing to do with what brand of DCC system you chose to use.
Sorry I was so touchy, do you think my math is wrong? It could be, Im no expert.Just graduated from tech school and thought I knew something, then poster corrected me, I overreacted. From the info the OP stated, I didnt think that any part of the layout would be farther than, say, 30ft from a booster. I didnt think voltage drop would be a factor at that length. I will see for myself if I ever get the layout finished.
mfm37 Voltage drop is one big reason to use large wire. Comparing the ampacity of low voltage house wiring to that of extra low voltage train layout wiring is like comparing apples to oranges. Lose 10% of voltage due to wire length on a home lighting circuit and most people wont notice that the 100 watt bulb now being lit with 108 volts is a little dimmer. Especially if they've never seen it brighter. Lose 10% on a 12 -15 volt rail bus and the command DCC command packets will no longer be reliable. Martin Myers
Voltage drop is one big reason to use large wire.
Comparing the ampacity of low voltage house wiring to that of extra low voltage train layout wiring is like comparing apples to oranges. Lose 10% of voltage due to wire length on a home lighting circuit and most people wont notice that the 100 watt bulb now being lit with 108 volts is a little dimmer. Especially if they've never seen it brighter. Lose 10% on a 12 -15 volt rail bus and the command DCC command packets will no longer be reliable.
Martin Myers
Im not sure why you chose to try to make me sound stupid, maybe left over from another thread?( PA2 Users Club) An 80ft long circuit, using 12ga copper wire, at 18volts and 5amps will have less than a 5% drop in voltage. From what the OP said, there shouldnt be anywhere near that long of circuit, so the drop will be much less and therefore, in this case, insignificant. 10% voltage drop will cause your DCC to be unreliable in reading packets? That I did not know. I didnt know they were that sensitive. Will a DCC system become unreliable if you run , say 4 sound locos on a 3.5amp system?
the important thing with soldering electrical connections is to be sure to use a flux only on 'clean' wires, not on of those active type fluxes that also cleans as it fluxes. if an active flux is used and the joint left unwashed, the joint WILL go green and corrode after a few years.
Take a couple of attaboys out of petty cash. Soldering is not as hard as some would think. I have a pair of auto stripping pliers that displaces the insulation when stripping the center of the wire. It works great on automotive stranded wire but has a hard time with household stranded getting a grip. Household or intererior wire has a slippery cover where automotive wire does not. The slippery cover helps pulling through conduit. You will be glad you soldered later on down the line. Suitcase or Scotch locks are a temporary fix and should never be relied upon for long turm use.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
locoi1sa My club just started the DC/DCC change over a couple weeks ago on the 40 year old permanent layout. Miles of wire were stripped out of it. Some parts were common rail wired and some were not. They had the old variarc controllers wired into 5 cabs and hundreds of blocks. 14 gauge wires for buss lines and 20 gauge feeders to terminal strips is what we decided on. Five districts with five boosters. I have seen what Scotch lock connectors look like after a few amps have been run through them. Use them on your layout but not mine. We have to try to accommodate all the members of the club. Some wanted it to be able to run DC or DCC with using a toggle to switch districts. Most of us are primarily DCC already and with a Lenz system able to run 00 the old holdouts will be accommodated. Pete
My club just started the DC/DCC change over a couple weeks ago on the 40 year old permanent layout. Miles of wire were stripped out of it. Some parts were common rail wired and some were not. They had the old variarc controllers wired into 5 cabs and hundreds of blocks. 14 gauge wires for buss lines and 20 gauge feeders to terminal strips is what we decided on. Five districts with five boosters. I have seen what Scotch lock connectors look like after a few amps have been run through them. Use them on your layout but not mine.
We have to try to accommodate all the members of the club. Some wanted it to be able to run DC or DCC with using a toggle to switch districts. Most of us are primarily DCC already and with a Lenz system able to run 00 the old holdouts will be accommodated.
Well i went down and worked on the layout yesterday. i decided to try soldering the feeder wires to the bus wire. i used the wire stripper to expose a section of wire. i think they are the "Ideal" brand strippers. that worked really well. that was my biggest concern in doing it this way. the time it would take to strip the wire. you have to be real careful not to cut into the wire. take your time. then i wrapped the feeder around the bus wire, a little flux, soldered together and taped the exposed section with electrical tape. to my surprise it wasn't that diffucuit and went quicker than i thought. I think i am moving away from the suitcase connectors. it takes a little more time, but not to bad for the better contact.
I think its good to remember that most outlets are wired with 14ga wire protected by a 15amp fuse or 12ga wire protected by a 20amp fuse. So, since your outlets/wiring wont handle anything more than 20amps(with 12ga)safetly, using anything larger is really overkill. You definetly want to check your circuits before plugging in all those boosters, + whatever else you might be using. I bring this up because my electrical teacher has told us many, many of horror stories of how people have wired circuits. THis is assuming that you havent looked over the breaker box yet of course. Voltage drop isnt a big factor unless your talking about really large layouts, but I went with 12ga for my buse even though 14 was probably just fine. I have my DCC system approx. 34ft from on end and 46ft from the other, although this may change before the layouts finished.
I like to strip the insulation on my feeder wires back about 2" after using the stripping tool to remove approx. 1/4" to 1/2" of insulation
on the buss wires i wrap the feeder wire (solid core 20g bell wire) around the now exposed buss wire. hit it with some flux on a micro brush and solder the connection. I like to wrap the connection with colored electrical tape indicating the same color used on the buss wire it's connected to.red/white. a good solder connection will never fail. When I see a car or a bike come into my shop and I spot suitcase connectors it spells out AMATEUR
Some are soldered and some are crimp on.
I like the DS-64s very much. Two of mine are powered by PS-14s, the rest are track powered. Eventually they will all be powered by PS-14s. I make extensive use of the ability to run routes.
Dave
Lackawanna Route of the Phoebe Snow
Phoebe Vet I have a 18x16 foot layout around a two car garage. I have 14 engines, 4 of them with sound, 8 lighted cars, and 8 DS-64s that are , for the moment, powered by the track. All that is powered by one Digitrax command station with no boosters. My track power connections are all stripped wires with spade connectors under screws on barrier strips. My switch and light connectors are European style strips. A suitcase style connector has to be sharp because it has to pierce the insulation and make contact with the wire within. That is what makes me nervous. The contact is sharp and the contact area is therefore very small. I can't say whether or not they work well, because i don't use them. I am just stating why I don't use them. I like the large surface area of the spade connectors under screws.
I have a 18x16 foot layout around a two car garage. I have 14 engines, 4 of them with sound, 8 lighted cars, and 8 DS-64s that are , for the moment, powered by the track. All that is powered by one Digitrax command station with no boosters.
My track power connections are all stripped wires with spade connectors under screws on barrier strips.
My switch and light connectors are European style strips.
A suitcase style connector has to be sharp because it has to pierce the insulation and make contact with the wire within. That is what makes me nervous. The contact is sharp and the contact area is therefore very small. I can't say whether or not they work well, because i don't use them. I am just stating why I don't use them. I like the large surface area of the spade connectors under screws.
do you solder the spade connectors?
actually the suticase connectors are not sharp, the metal is the same width on the whole piece. it is just that the insulation is soft, so it has no problem pushing it away and making contact with the wire. it doesn't cut the wire either if you use the right size. stranded maybe one strand.copper is soft and as you push the metal connector down on the wire the gap actually spreads. is a tight connection. the reason i know this is when i first got them, i used one and then opened and cut them apart to see how they worked. stranded actually seem to work better because the wire compresses and you have more contact on the wire.
another thought is i have done alot of basic home wiring, plugs and switches. more volts and amps. if you have replaced a plug in your house, you can usually wire it to a screw terminal on the side or just shove it in the back to the connector. that connector does not really make much more contact than a suitcase connector
how do you like the ds-64's?
thanks for the input, i really like the options and feedback
I figure there are about 3 trains on each mainline, with a minimum of two locos on each train, plus a few in locos in the yard. Most everything has sound and there will be additional ones just idle with sound. lets say 25 max.
i have heard that the suitcase connectors can fail, but mostly in situtations where they are exposed to the elements and movement (cars) thinkgs like that. these would be under the layout not really any movement. i also prefer to put feeders every 3-4 feet not 6. if one does fail i think we should be covered. I also believe that you should not count on a rail jointer for conducting power. feeder to every rail that is not soldered together. I was also going to leave a little extra feeder wire. we could always come back and solder or put in another connector if needed.
i believe that you wire one section, test and then move to the next. this also keep the layout or most of it operational
this brings up another question. if people are using teminal blocks, wouldn't you have the same contact as a suitcase connector. A terminal is just a screw pushing the the wires together and the suitcase pinches the wire with the little metal piece . seems like the same sort of contact.
i do like the idea of putting the boosters in different locations. My layout at home will be like that. but i think they will all have to be together at the club layout.
thanks for everyones input, it is helping i am feeling that i am moving in the right direction.
In the aircraft maintenance business (my former trade) and on my personal layout, we have a word for electricians who use suitcase connectors:
DE-CERTIFIED!
I personally, use screw terminals (actually stud-and-nut terminals) for my analog DC electricals. If I was into DCC, my bus-to-feeder connections would all be soldered, and painted with liquid insulation.
Suitcases are fine for packing clothes. They have no place on a wiring system designed to be bulletproof. Not to mention that you can buy a LOT of solder and flux for the price of a fairly small number of suitcase connectors.
Chuck (Modeling Central Japan in September, 1964 - with bulletproof electricals)
That is a very nice installation. I am a big believer in neat and clearly labeled. I also agree that the command station or booster should be in the middle of the district it powers.
I have never used Suitcase style connectors. They look easy but I am a little punchy about stabbing into a wire through insulation. I use terminal strips, but I follow threads that discuss other methods with great interest.
Solder not only strengthens a mechanical electrical connection, but also protects it from future corrosion.
If possible, put the boosters central to the power district they run. Loconet cable can be run much longer than bus wires. Try to keep the bus wires less than 30 feet in any one direction. On our portable layout we fabricated boxes holding the booster, PM42 breakers, plug in panels (one has a UR91 radio deal, one has a LNRP), and power supplies. Pull the plugs, two pins, and it comes out for transport.
We have three, spaced out to be centrally located to the districts they power.
I highly prefer soldering feeders to bus wires. Get a good wire stripper. Scotchlocs are spendy, and I feel less than reliable in the long haul. In some spots we do use spade terminals to a terminal block. Do not just strip wire and run it under a screw, proper terminals are essential.
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
Our club has a 27' by 27' layout(two levels). We have three 8 amp boosters. We ran 12 gauge wire for the 'bus', and 18 gauge for the actual track feeders( ScotchLoc 567). There is a ScotchLoc connector for 14 gauge bus/20 gauge tap(905 IIRC) and that is what I used on my home layout. We have had no issues with them. I would suggest you buy one of those expensive 'crimping tools' for them - it really is better than using pliers. We have an area when one guy 'hand crimped' using a pair of channel locks, and one of the connections failed after 18 months. - recrimping with the 'tool' resolved the problem(and I recrimped all of the connection in that area to make sure). I even borrowed the club's tool and re-did mine(about 150 connections) just to make sure).
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
rrinker Phoebe Vet "There will be 5 digitrax boosters to start located in the center of the room." How many trains are you going to be running that you need 5 boosters? On a 30x40 club layout, especially during open houses, I would expect the answer to be "a lot". Probably not overkill. --Randy
Phoebe Vet "There will be 5 digitrax boosters to start located in the center of the room." How many trains are you going to be running that you need 5 boosters?
"There will be 5 digitrax boosters to start located in the center of the room."
How many trains are you going to be running that you need 5 boosters?
On a 30x40 club layout, especially during open houses, I would expect the answer to be "a lot". Probably not overkill.
You can sure run a lot of trains with 25 amps of power. My microwave oven only draws 14 amps.
personally i say solder everything. i fitted a GPS tracker using scotch locks and first attempt one of them didn't quite cut through the insulation. i spoke the the company that supplied the kit and they said they prefer soldering themselves because with any movement the scotch locks can become intermittent but home fitters aren't usally upto soldering so they supply scotch locks!!. i realise there will be plenty of folks that have used scotch locks and are happy a year down the line cos the layout is permanent. but a club layout that may get moved or taken to exhibitions could start to suffer eventually. decent solder joints won't cause trouble. put the effort in now rather than later fault finding. soldering also looks neater rather than dyslexic lego everywhere.
I have used scotchlok #567 with 12G buss and 20G feeders with no problem. It is a rather small layout, 8 x 22 feet. Am pulling 13.9 volts everywhere on the layout.
Tom
I am a big fan of soldering. Some people swear by Scotchloks, some people swear at them. I believe the one size will do #20 tap into a #14 bus, but they don;t have one that does $20 into #12. The idea of runnign #12 until you get close to the area and the switch over to #14 is a fine idea and should work with no problems.