Wire Gauge, amperage, voltage, track drops, and distance with today's steam locomotives

Don't worry about the chart. Use 14 ga for all track power, and 18 ga for accessories.

Lionel recommends 14 ga from the 180w brick to the track.

I ran #14 all around for power distribution and I used #18 for the actual short drops from the track.  I have zero issues with power drops anywhere on the layout.

@trainmanmason posted:

....  I was hoping not to have to go to 18 gauge....but, I will if it's necessary!

Time to be generous with the wire size so you don't have issues!

18 gauge won't run much and 22 is out of touch with reality.

@trainmanmason posted:

If I was to double head a Lionel Vision Line Big Boy, with a Lionel Vision Line Challenger, and a consist of 10 candescently lit 21 inch passenger cars....What would the amperage be needed for that?  A best guess would be helpful.

When I turn on all the smoke features of my VL-BB, it draws close to four amps running with a 30 car consist.  I haven't double-headed it with my VL-Challenger, but I'm guessing we'd be in the 7-8 amp range with both of them with everything enabled.

21" incandescent passenger cars will each draw 400-500 milliamps, so ten of them would total up between 4 and 5 amps.

@gunrunnerjohn posted:

When I turn on all the smoke features of my VL-BB, it draws close to four amps running with a 30 car consist.  I haven't double-headed it with my VL-Challenger, but I'm guessing we'd be in the 7-8 amp range with both of them with everything enabled.

21" incandescent passenger cars will each draw 400-500 milliamps, so ten of them would total up between 4 and 5 amps.

Thank you, John for the info!!  I had just started wiring my track and knew I should check before I got too far.  By the way, are you using stranded or solid core 14 gauge wire?

@Engineer-Joe posted:

Time to be generous with the wire size so you don't have issues!

18 gauge won't run much and 22 is out of touch with reality.

Thank you, Joe!

@trainmanmason posted:

Thank you, John for the info!!  I had just started wiring my track and knew I should check before I got too far.

Convert those passenger cars to LED lighting and you'll have much better flicker-free lighting and also they'll draw about 10% of the power they do now.

PIE    Power (watts) = Volts (E) X Amps (I)

180-watt power supply = 18 volts X 10 amps

The larger gauge number the smaller the conductor, the smaller the conductor and/or the greater the length of wire run, the greater the voltage drop.

Conductor size or gauge is rated for max volts dependent on type of insulation. Conductor size is rated at maximum amps for that conductor's ability to handle the heat created by amps (current) and subsuquent insulation failure from an overloaded condition.

In general, although the conductor in a wire conducting excessive amperage above rating can handle the heat, however the insulation will fail, connections will fail, and a fire may start

Voltage -drop tables are easy to google, good rule of thumb try to not to exceed 5% voltage drop.

Should you experience a large voltage drop, Current (amps) will increase if the power (motor) remains the same

consider reading up or video's on "ohm's law"

stick with pure copper conductors

I’m not sure of the source of that chart, but those calculators are usually geared towards house wiring. Typically you want branch circuits in your house to have 3% voltage drop MAX over their run from the internal resistance of the wire. Having 2V of drop is fine in a 120VAC circuit, but for 18V track power it’s too much.

If you figure a 5% drop with 18 volts at 6 amps, that's 60 feet of #14 copper wire.  Since you have to account for the distance out and back, it's a 30 foot run.  If you're smart about where you put your power distribution panel, that will accommodate a pretty large layout.  My layout is 12 x 24 with a 15 foot yard extension out one end.  I used #14 throughout for power bus, and I've had no issues at all with power drops running conventional or command.

At 18 VAC a 5% drop would =  .9volt .  approx.

rplst8, I believe you have a good point. 

An example 18Vac on 14 gauge cooper conductor run 25'  drawing 6 amps would experience a 5.17% voltage drop or 18 volts at transformer and 17 volts at track connection.  Maybe I should stay away from rule of thumb advise and stick with actuals.

If you want to easily calculate voltage drop search " voltage drop calculator"

GRG is correct, calculations change with different calculators and things like wire bundling, ambient temperature as well as conductor purity and material. He makes a good point of reference for many, as to wiring up their layout. !4 Ga. a more practical and useful answer.  From transformer to track drops 14 gauge may well be my choice.

should I use stranded 14 gauge copper vs solid core?

@trainmanmason posted:

should I use stranded 14 gauge copper vs solid core?

Yes, stranded.

You can use solid copper, but it's hard to work with, so I always use stranded copper.  I bought my #14 THHN copper wire at Home Depot in 500 foot reels.

@Fast Mail posted:

PIE    Power (watts) = Volts (E) X Amps (I)

180-watt power supply = 18 volts X 10 amps

The larger gauge number the smaller the conductor, the smaller the conductor and/or the greater the length of wire run, the greater the voltage drop.

Conductor size or gauge is rated for max volts dependent on type of insulation. Conductor size is rated at maximum amps for that conductor's ability to handle the heat created by amps (current) and subsuquent insulation failure from an overloaded condition.

In general, although the conductor in a wire conducting excessive amperage above rating can handle the heat, however the insulation will fail, connections will fail, and a fire may start

Voltage -drop tables are easy to google, good rule of thumb try to not to exceed 5% voltage drop.

Should you experience a large voltage drop, Current (amps) will increase if the power (motor) remains the same

consider reading up or video's on "ohm's law"

stick with pure copper conductors

Thank you so much for the information!

Another question.  For the insulated track sections I have to create for the lift bridges, bascule bridge, swing bridge, I assume I will also have to use 14 gauge wire for the U (Center Rail Terminal) connectors on those bridges, too?  The reason I ask is that those connectors are not too big for one (let alone two for going in both directions) 14 gauge wires.  It just means I'll have to modify the connector to accommodate that gauge of wire.  I just want to make sure I'm thinking this through correctly.

Also, are you soldering these 14 AWG wires directly to the track (that's how I use to do it, but this is a very large wire)?

I use #18 wire for my track drops, I connect to the #14 wire under the layout using lever nuts.  I actually went around and put in all the track drops, then ran the #14 wire to connect everything.

@gunrunnerjohn posted:

I use #18 wire for my track drops, I connect to the #14 wire under the layout using lever nuts.  I actually went around and put in all the track drops, then ran the #14 wire to connect everything.

Thank you, John....I see how these are to be connected, but forgive me, I'm not picturing how this connects power to the track?  Also, what do you mean by a "track drop?"

You pick up a lever, shove a stripped wire in, and click the lever down.  It's just like any other connector.

@gunrunnerjohn posted:

You pick up a lever, shove a stripped wire in, and click the lever down.  It's just like any other connector.

I understand that for connections....I guess you are still having to solder the wire to the track, right?

Not for everyone, but what I did: two 12 gauge solid copper bus wires under the layout. Two 20 gauge solid copper drops soldered at rail and bus on every separate track section, each about 9 inches long. Some exceptions: on bridges, track sections were soldered directly together with 20 gauge tinned copper splices; on some 3 foot Gargraves sections, I got lazy and soldered the feeders to the pins between the sections. mostly because I had a heck of time getting solder to stick to the black center rail.

20 gauge solid copper is most economically available as electric dog fence wire, I've gotten reels at Chewy.com and Lowes.  For the 12 gauge, I use the bare copper wire as the bus for the outside rail, black for center rail, and white for whichever one I need it for.

If you plan to use any Z-stuff components, make sure all your ground buses are soldered together.

GRJ's sizing is fine. I am using #16 track drops, #14 within blocks, and #12 home runs from the power bricks to block toggle switches (regionalism around the layout), all stranded. Because I have the wire rolls lying around. The ABYC tables for DC systems in recreational boats are a useful reference. For example, they specify #14 for 10% drop at 30 feet, 10A, 12 V (out & back) and #12 for 3% drop at 24V and 10A.

Forgive me...But I'm trying to understand the jargon....What is meant by "Track Drops?"

I used the term "drops" to refer to the 9" long 20 gauge copper wires that are soldered at one end to the rail and at the other to the 12 gauge buses under the layout.

@trainmanmason posted:

Forgive me...But I'm trying to understand the jargon....What is meant by "Track Drops?"

Usually people run “bus wires” under the layout framework using a large size wire. Then every so often there are smaller wires that are connected to the track, and “drop” down through the base board and connect to the bus wires.

@trainmanmason posted:

I understand that for connections....I guess you are still having to solder the wire to the track, right?

Yes, I soldered all the track drops directly to the track.  Some like to solder on the bottom and then place the track, but I had all the track laid and tied down and then drilled the holes and soldered the track drops to the track.

GRG.

Hey John,

Did you isolate your center rails between wire drops or did you leave center rail electrically continuous or a combination of both? And is the DCS signal working out good for you. Thanks for any feedback

I never got around to cutting the center rails between drops, but I haven't had any DCS issues, most of my readings are 9's and 10's around the layout.  Given the success, I moved on to other issues and never bothered doing the cuts.

GRG

Good to know that was going to be my approach. Only cut center pins if I have DCS signal issues. With wire drops about every 12-15 feet or every 5-6th section. Thank you, that is reassuring. kevin

My drops are probably every 8-10 feet, I know I wanted to make sure I didn't have power issues, that worked out well.  I also ran drops from the left and right rail separately and tied them together with the lever nuts.  If I ever want an insulated rail signal, it will be easy to remove the drop, chop the rail, and I'll have my insulated section.

GRG

John,

I not sure what frequency you broadcast on, but you are coming through loud and clear. Today a big box of lever nuts arrived from AMZ  I must have got the idea somewhere, must have been you, Thanks kevin

I thought you were not supposed to go from a large gauge wire to a smaller gauge wire (when you connect to a bus of a bunch of 20 gauge consumers of the connected 14 gauge terminal of the bus?  Especially to go from a 14 gauge to a 20 gauge wire??  I drew a crude picture to make sure I'm understanding what you are meaning by track drop and to go thru a terminal bus. 

@trainmanmason posted:

I thought you were not supposed to go from a large gauge wire to a smaller gauge wire (when you connect to a bus of a bunch of 20 gauge consumers of the connected 14 gauge terminal of the bus?  Especially to go from a 14 gauge to a 20 gauge wire??  I drew a crude picture to make sure I'm understanding what you are meaning by track drop and to go thru a terminal bus.

Your drawing is correct. There’s no reason one can’t go to a smaller gauge in this application because the primary reason for the larger gauge wire is to prevent voltage drop. Also, it is unlikely that you would exceed the ampacity of the smaller gauge in any given “block” since it would be hard to fit two trains in it.

The other thing to remember is that the current rating for a wire is partially based on size/gauge and partially based on length. Short drops of 12 inches or less should not pose any problems.

Thank you!!!!  I'm understanding now.  That will make soldering much easier to go to the track using 20 gauge wire instead of 14 gauge.  Okay....John stated, he's going 8 to 10 feet for 20 gauge drops.  Is that too long for 20 gauge or just about right (especially when double heading two of todays larger Vision Line steam locomotives?  By what he explained he was having no issues.

I use 18ga drops, but the same would apply to a 20ga drop, it's not that much difference.  As stated, a #20 wire around 12" long will have a truly minimal voltage drop, even with lots of current.  Two feet of #20 wire carrying 10 amps will drop about .3 volts.  I say two feet because presumably you have the drop from the outside rail as well.  Now, it's going to be vary rare you carry 10 amps, so the drop will be even less.  With 3 watts of dissipation, the wire won't even get warm.

There's no reason to try to solder #12 or #14 wire to the track, it just makes the job harder with minimal gain.

Remember: Perfect is the enemy of good enough.

Thanks for everybody's help.  Okay....so my question is now...What is the recommended safe maximum drop distance (length of track until I connect another drop) for 18 gauge wire?  20 Gauge wire?

There is no stated minimum or maximum distance between drops.  Personally, I placed a drop about every eight to ten feet on most of my track.  It's probably overkill, but I can say that I have experienced no power drop issues.  I can even run conventional stuff around and not see any speed variation other than the obvious one posed by the grade to the second level.

@gunrunnerjohn posted:

When I turn on all the smoke features of my VL-BB, it draws close to four amps running with a 30 car consist.  I haven't double-headed it with my VL-Challenger, but I'm guessing we'd be in the 7-8 amp range with both of them with everything enabled.

21" incandescent passenger cars will each draw 400-500 milliamps, so ten of them would total up between 4 and 5 amps.

I was wondering that if there is a voltage drop and the cars are lighted with incandescent bulbs, wouldn't the amp draw go up?

If so, on layouts with some wiring flaw, the results can be worse than estimated.

I know that when I tested my layout without DCS, I was surprised by voltage drops around the layout. I added drops and that helped my newest MTH Bigboy get around better. It seems to be a power hog! I only had one really weak area on each 2 rail mainline, but it caused issues.

I had run a 10 engine train with 2 sets of 5 diesels, and never noticed any problem, even with the smoke on.