DCC Wiring

18 step-by-step guides · 101 videos · Wire Size Finder

DCC Wiring Guide

Wire your layout right the first time. Start with the basics (bus and feeders, turnouts, reverse loops), then move on to boosters, block detection, signals, automatic braking and throttle networks. Each guide has simple steps, the best videos and the parts you need.

7 basic guides7 advanced guides4 network guidesWire Size Finder →
Proud sponsorIron Planet Hobbies sponsors Wiring for DCC, Allan Gartner's free DCC wiring reference since 1996. Many of the steps on this page come from his site.Visit WiringForDCC.com ↗
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18 guides
01Basic DCC WiringHow DCC Power WorksCommand station, booster, decoders and track: what each part does and why wiring matters more than it did with DC.Beginner▶ 6 videos02Basic DCC WiringTrack Bus & FeedersHeavy bus wires under the layout, short feeders up to the rails. The right sizes for every scale.Beginner▶ 6 videos03Basic DCC WiringThe Quarter Test & Finding ShortsThe one test every DCC layout must pass, plus a fast way to track down a short.Beginner▶ 4 videos04Basic DCC WiringDCC-Friendly Turnouts & FrogsInsulfrog, Electrofrog, Unifrog and "DCC friendly": what they mean, and how to power a frog.Beginner▶ 6 videos05Basic DCC WiringReverse Loops, Wyes & TurntablesSpot a reversing section, gap it the right way and keep it from shorting.Beginner▶ 6 videos06Basic DCC WiringProgramming TrackAn isolated track for setting loco addresses and CVs, without reprogramming every engine on the layout.Beginner▶ 5 videos07Basic DCC WiringTurnout Control & Stationary DecodersSwitch machines, servos and stationary decoders, plus when an accessory bus makes sense.Beginner▶ 6 videos08Advanced DCC WiringPower Districts & Circuit BreakersSplit one booster into protected districts, so a short in the yard doesn't stop the main line.Intermediate▶ 6 videos09Advanced DCC WiringAuto ReversersPick and tune an auto reverser so it flips polarity before your booster or breaker trips.Intermediate▶ 6 videos10Advanced DCC WiringBoosters: Common Ground vs Opto-IsolatedWhen to add a booster, how to wire booster districts, and why the ground wire matters.Advanced▶ 6 videos11Advanced DCC WiringBlock DetectionLet the layout know where trains are: the starting point for signals, panels and automation.Advanced▶ 6 videos12Advanced DCC WiringSignalingABS, APB and CTC basics, and how detectors, logic and signal heads fit together.Advanced▶ 6 videos13Advanced DCC WiringABC Braking: Stop at SignalsAsymmetric DCC (ABC) makes locos slow and stop in front of a red signal, then pull away when it clears.Advanced▶ 6 videos14Advanced DCC WiringShuttle Trains & Simple AutomationTrains that run back and forth on their own: three ways to do it with DCC.Intermediate▶ 5 videos15Throttle & Layout NetworksLocoNet (Digitrax)Free-form, 6-wire flat cable network for Digitrax throttles, boosters, detectors and accessories.Intermediate▶ 6 videos16Throttle & Layout NetworksNCE Cab BusNCE's daisy-chained throttle bus: cables, panels, cab addresses and length limits.Intermediate▶ 5 videos17Throttle & Layout NetworksXpressNet & Multi-Bus SystemsLenz's XpressNet, and command stations that speak several networks at once.Intermediate▶ 5 videos18Throttle & Layout NetworksLCC: Layout Command ControlThe NMRA's layout network for signals, turnouts, detection and lighting, kept separate from DCC.Advanced▶ 6 videos
Basic DCC Wiring · Guide 1 of 18

Basic DCC Wiring

How DCC Power Works

With DCC, the rails always carry full power plus a digital signal. Every locomotive has its own address, so you run trains instead of track blocks. That freedom has one catch: DCC is far less forgiving of weak wiring and dirty track than DC was.

BeginnerBefore you buy anything6 videos

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DCC Starter Sets Command Stations Boosters Throttles

Step by step

  1. 1

    Know the four parts

    The command station builds the commands. The booster turns them into track power. Throttles tell the command station what you want. Decoders in each locomotive listen for their own address. Starter sets combine the command station, booster and throttle in one box.

  2. 2

    The track carries power and data

    DCC track power is a fast-switching form of AC. The decoder reads the timing of those switches as commands. Short power drop-outs that DC ignored, from dirty track or loose joiners, can scramble those commands.

  3. 3

    Direction comes from the throttle

    A DCC loco runs the way you tell it to, no matter which rail is which. That's why trains can roll straight through an auto-reversing section without stopping.

  4. 4

    You don't need DC-style blocks

    There are no cab blocks or toggle panels. You only cut rail gaps for reversing sections, block detection, power districts and boosters. Allan Gartner still recommends a few sections on anything bigger than a 4x8, so you know where to look when there's a short.

  5. 5

    Size your system by trains, not square feet

    Booster capacity depends on how many locomotives run at once, not on layout size. Allan's rule of thumb: a 5-amp booster runs six to eight HO locomotives.

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How to Get Started With DCC for Model TrainsIron Planet Hobbies
DCC Basics: Track Power, How Does It WorkModel Railroading
DCC Basics: Command Stations & BoostersModel Railroading
DCC Basics: What Are All These Wires For?Model Railroading
How Does DCC Work and How Do I Wire for It?DIY and Digital Railroad
Zephyr Express Quickstart GuideDigitrax

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Next: Track Bus & Feeders →
Basic DCC Wiring · Guide 2 of 18

Basic DCC Wiring

Track Bus & Feeders

The bus is a pair of heavy wires that runs under the layout and follows the track. Short, thin feeders drop from the rails to the bus. Get this right and your locos run smoothly, and every short shuts the booster down like it should.

BeginnerWhile you lay track6 videos
Sizing your wire? The Wire Size Finder gives bus and feeder sizes for your scale and run length.

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Wire & Accessories Wire Strippers & Crimpers HO Joiners & Accessories Power Management

Step by step

  1. 1

    Pick a bus size for your scale

    Allan Gartner's suggested bus sizes: Z and N 16–14 AWG, HO 16–12 AWG, S, O and G 14–10 AWG. Solid wire is easy to strip mid-run for feeders. Bigger is always fine, so use the Wire Size Finder below for long runs.

  2. 2

    Color-code the two rails

    Use one color for each rail (for example red and black) and keep them the same everywhere. If you ever find red facing black across a gap, you've found a reversing section.

  3. 3

    Drop feeders from the rails

    For HO, 22–20 AWG solid feeders work well, and 24 AWG is fine if every 3-ft piece of rail gets one. Keep feeders about 6 in. long or less with the thin sizes, up to about 12 in. with the thicker ones. Solder them to the outside of the rail.

  4. 4

    Space feeders often

    About every 10 ft for code 100 rail and every 6 ft for code 83 and smaller. N and Z need feeders every 3 to 6 ft because the small rail has more resistance. Weathered rail or unsoldered joiners: a feeder on every piece.

  5. 5

    Connect feeders to the bus

    Solder them, or use connectors made for your wire size (suitcase, IDC or push-in). IDC connectors have to match the wire gauge, need the right tool and can't be reused.

  6. 6

    Twist long runs

    If the bus runs more than about 30 ft from the booster, twist the pair (Allan: about 1–3 twists per foot) and add an RC snubber at each end of the bus (never at the booster). Check your system's advice first: Digitrax recommends no snubbers on their equipment.

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DCC Power Bus and Track FeedersModel Railroading
Wiring Your Model Railroad for DCCModel Railroading
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How to Wire Your Layout for DCC Using Bus and Feeder WiresOlliead
How I Install DCC Power Bus WiringJohn Tanzillo
DCC Bus Termination Made SimpleĦal-Zuzzu Model Railway

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DCC Main Bus Wire · Black · 14 AWG · 50 FeetNCEDCC Main Bus Wire · Black · 14 AWG · 50 Feet$22.17In stockTrack Bus Taps · 14-16 AWG Blue · 32 PiecesNCETrack Bus Taps · 14-16 AWG Blue · 32 Pieces$12.44In stockDCC Track Bus Spike Suppressors & Terminators · Snubber · 2 PackDCCconceptsDCC Track Bus Spike Suppressors & Terminators · Snubber · 2 Pack$10.32In stockHigh Quality Power Bus Wire Strippers · DCT-BWSDCCconceptsHigh Quality Power Bus Wire Strippers · DCT-BWS$26.91In stockHO Scale · Code 83 & 100 Nickel Silver Terminal Joiners · With 22-Gauge Wire · 2-PackWalthers TrackHO Scale · Code 83 & 100 Nickel Silver Terminal Joiners · With 22-Gauge Wire · 2-Pack$5.58In stockHO Scale · Code 83 · Terminal Rail Joiners (1 Pair)AtlasHO Scale · Code 83 · Terminal Rail Joiners (1 Pair)$4.02In stockSPL-62 · Multiple Terminal Block Push-In Wiring Quick Cable Connector · 2 In, 6 OutRR-CirKitsSPL-62 · Multiple Terminal Block Push-In Wiring Quick Cable Connector · 2 In, 6 Out$1.44In stockSolid Brass Power Distribution Bars · 2 Pieces · DCC-Bbar2DCCconceptsSolid Brass Power Distribution Bars · 2 Pieces · DCC-Bbar2$10.32In stock
← How DCC Power WorksNext: The Quarter Test & Finding Shorts →
Basic DCC Wiring · Guide 3 of 18

Basic DCC Wiring

The Quarter Test & Finding Shorts

Lay a coin across the rails anywhere on the layout. The booster (or circuit breaker) must shut down, every time, everywhere. If it doesn't, the wiring is too weak. A short that never trips can melt ties and wire, or start a fire.

BeginnerAfter wiring each section4 videos
Sizing your wire? The Wire Size Finder gives bus and feeder sizes for your scale and run length.

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Power Management Wire & Accessories DCC Accessories

Step by step

  1. 1

    Do the quarter test everywhere

    Short the rails with a coin or screwdriver at the far ends of every section, on sidings and on powered frogs. Each one must shut the power off right away. Allan Gartner: every manufacturer will tell you the same.

  2. 2

    If it fails, check the bus first

    Short the bus wires right at a feeder. If that trips but shorting the rails above doesn't, your feeders are too thin, too long, or badly connected.

  3. 3

    Check the joints

    Good solder joints are smooth and shiny, with no brown residue or blob. If you didn't solder feeders to the rails, start there.

  4. 4

    Make sure the power supply is big enough

    The booster's power supply must be rated at least as high as the booster. A small supply can make good wiring look bad in this test.

  5. 5

    Split the bus to find a short

    Disconnect the bus in the middle and test each half. Keep halving the side that still shorts. With 16 feeders you'll find the bad one in about four cuts instead of sixteen.

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Wiring Your Model Railroad for DCC: ProblemsModel Railroading
Don't Burn Your Wires or Blow Your BoostersModel Railroading
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← Track Bus & FeedersNext: DCC-Friendly Turnouts & Frogs →
Basic DCC Wiring · Guide 4 of 18

Basic DCC Wiring

DCC-Friendly Turnouts & Frogs

Turnouts cause more DCC shorts than anything else. The fix is simple: point rails that always match the stock rail next to them, and a frog that's either dead (plastic) or powered with the right polarity for the route.

BeginnerBefore you buy turnouts6 videos

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HO Turnouts N Turnouts Frog Juicers Switch Machines HO Joiners & Accessories

Step by step

  1. 1

    Know what "DCC friendly" means

    On a DCC-friendly turnout, each point rail is always the same polarity as the stock rail beside it, and the frog is isolated from both. Walthers' DCC-friendly design, for example, drops the bar that tied the two point rails together.

  2. 2

    Insulfrog: plug and play

    Peco Insulfrogs have a plastic frog that can't be powered. They're the easiest to wire, but short locos can stall on the dead frog.

  3. 3

    Electrofrog and Unifrog: power the frog

    A metal frog conducts all the way through, so it needs the right polarity for each route. Gap the rails beyond the frog as the maker says, and feed the frog through switch machine contacts or a frog juicer. Peco Unifrogs ship ready to wire either way.

  4. 4

    Pick how to switch frog polarity

    Use the spare contacts on a Tortoise or similar slow-motion machine, a small relay, or a frog juicer. A frog juicer senses the short when wheels bridge the gap and flips the frog in an instant, with no contacts to adjust.

  5. 5

    Gap and feed the sidings

    Use insulated joiners where the maker says, and give every track leaving a turnout its own feeders. Don't rely on the points to carry power.

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DCC Friendly Turnouts: Do You Know What It Means?Model Railroading
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← The Quarter Test & Finding ShortsNext: Reverse Loops, Wyes & Turntables →
Basic DCC Wiring · Guide 5 of 18

Basic DCC Wiring

Reverse Loops, Wyes & Turntables

Any track that lets a train turn around brings one rail back to meet the other rail. Where they meet, you get a dead short. The cure: cut that piece of track off with gaps in both rails, and flip its polarity before the train crosses back.

BeginnerWhen you plan the track6 videos
Not sure you have one? Check your track against the Track Plan Check.

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Auto Reversers HO Joiners & Accessories N Joiners & Accessories Switch Machines

Step by step

  1. 1

    Find every reversing section

    Wyes, balloon loops, turntables, dogbones with a crossover, and ovals with a diagonal track across the middle all reverse. Follow one rail color around: where red meets black, you have one. Use the Track Plan Check below.

  2. 2

    Gap both rails at both ends

    Isolate the reversing section with insulated joiners or cut gaps in both rails at each end. Feed it from its own pair of wires.

  3. 3

    Make it longer than your longest train

    The whole train has to fit inside the section, or the train will bridge both gaps at once and short no matter which way the polarity is set.

  4. 4

    Choose manual or automatic

    A DPDT toggle, or the spare contacts on the turnout's switch machine, can flip polarity by hand. An auto reverser does it on its own the instant the wheels cross a gap. See Auto Reversers in the advanced section.

  5. 5

    For a wye, pick one leg

    Make the tail track the reversing section and include the turnout it connects to, or gap one leg. A turntable bridge always needs its polarity flipped, by a reverser or by contacts on the turntable.

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Fully Automate Your DCC Reverse LoopsModel Railroading
How To: Reversing Loops on a Digital Model RailroadJim Zim
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← DCC-Friendly Turnouts & FrogsNext: Programming Track →
Basic DCC Wiring · Guide 6 of 18

Basic DCC Wiring

Programming Track

Service-mode programming broadcasts to every decoder on the rails, so changing one address on the main line can change them all. A short, isolated programming track makes sure only the loco on it hears the command.

BeginnerBefore your first decoder5 videos

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Command Stations DCC Accessories Wire & Accessories

Step by step

  1. 1

    Know the two programming modes

    Service mode (programming track) can write and read any CV, including the address. Ops mode, or programming on the main, talks to one address on the running layout. It's great for tweaks but usually can't read values back.

  2. 2

    Isolate a piece of track

    Gap both rails so the programming track can't connect to the main layout. A yard lead or a bench test track both work.

  3. 3

    Wire it to the PROG output

    Connect it to the command station's programming terminals, not the main track output. Digitrax: it's very important the rest of the layout can be isolated when you program.

  4. 4

    Switching on the layout

    If the programming track is also part of the layout, use a DPDT switch to connect it either to the main bus or to the programming output, never both at once.

  5. 5

    Sound decoders that won't read

    Some sound decoders need more current than a programming track gives. A programming booster, or a stand-alone programmer like the SPROG or PR4, solves it.

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Watch how it's done

Add a Dedicated Programming TrackModel Railroading
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← Reverse Loops, Wyes & TurntablesNext: Turnout Control & Stationary Decoders →
Basic DCC Wiring · Guide 7 of 18

Basic DCC Wiring

Turnout Control & Stationary Decoders

Turnouts can be thrown by hand, from fascia buttons, or by DCC from your throttle. A stationary decoder turns DCC commands into motion for a Tortoise, a servo, a snap (twin-coil) machine or a Kato or Bachmann turnout.

BeginnerAfter the track works6 videos

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Switch Machines Stationary Decoders Turnout Control Panels, Buttons & Toggles

Step by step

  1. 1

    Pick the switch machine

    Slow-motion stall motors (Tortoise, Cobalt) move the points gently and have spare contacts for frog power. Servos are small and cheap. Snap (twin-coil) machines are fast and need a pulse of power.

  2. 2

    Match the stationary decoder

    The decoder has to match the machine: slow-motion, solenoid, or servo. Digitrax's DS74, for example, does both slow-motion and solenoid modes, and NCE's Switch8 runs eight Tortoise or Cobalt machines.

  3. 3

    Power it from the track or a separate bus

    Small decoders can take power from the track. On bigger layouts, a separate accessory bus keeps turnouts working when a short drops track power.

  4. 4

    Add fascia controls

    Push buttons or fascia controllers let operators throw turnouts where they stand, and many decoders report the turnout position back to the system.

  5. 5

    Give each one an address

    Program the decoder's address once, then throw it from a throttle or a JMRI panel.

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Watch how it's done

How to Use Slow Motion Turnouts on the DS74Digitrax
How to Use Solenoid Mode on the DS74Digitrax
Do You Need a DCC Accessory Bus?Model Railroading
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← Programming TrackNext: Power Districts & Circuit Breakers →
Advanced DCC Wiring · Guide 8 of 18

Advanced DCC Wiring

Power Districts & Circuit Breakers

Without districts, one derailment shuts down the whole layout. Electronic circuit breakers split a booster's output into districts that trip on their own, and they react faster than the booster, which protects decoders and wiring.

IntermediateOn anything bigger than a 4x86 videos

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Power Management HO Joiners & Accessories Wire & Accessories

Step by step

  1. 1

    Plan districts around operators

    Give the yard, each town, staging and the main line their own districts. That way one operator's short doesn't stop everyone else.

  2. 2

    Gap both rails between districts

    Each district gets its own sub-bus from its breaker. Gap both rails where districts meet.

  3. 3

    Set the trip current

    Set each breaker below the booster's limit so it trips first. NCE's EB1 adjusts from 1.5 to 8 amps (factory 1.5). Digitrax's PM74 defaults to 4 amps, with 3 or 6 as options.

  4. 4

    Do the quarter test on every district

    After setting breakers, test each district at its far end. Allan Gartner calls this imperative.

  5. 5

    Mind the reversers

    Auto reversers and circuit breakers both react to shorts. The reverser must flip faster than the breaker trips, so check that the two work together.

Go deeper on Wiring for DCC

Watch how it's done

Protect Your Layout With a DCC Circuit BreakerModel Railroading
Demystifying DCC Circuit BreakersModel Railroading
Wiring Your Model Railroad for DCC: Power ManagementModel Railroading
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How to Build a Layout: Districting Your LayoutTrainWorldTV
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← Turnout Control & Stationary DecodersNext: Auto Reversers →
Advanced DCC Wiring · Guide 9 of 18

Advanced DCC Wiring

Auto Reversers

An auto reverser watches a reversing section. When wheels bridge a gap and cause a short, it flips the section's polarity in a few thousandths of a second, so the train rolls on and the booster never notices.

IntermediateAfter the reversing section is gapped6 videos

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Auto Reversers Frog Juicers Power Management

Step by step

  1. 1

    Wire it between the bus and the section

    Two wires come in from the main bus and two go out to the reversing section. Nothing else should feed that section.

  2. 2

    Set the trip point

    Digitrax's AR1 has an adjustable trip from 0.25 to 8 amps. Set it with your heaviest train in the loop: it should flip once going in and not trip again. If the booster trips instead, turn the setting down.

  3. 3

    Make it faster than the breaker

    The reverser has to react before the booster or circuit breaker upstream. If the breaker wins, add a delay to the breaker or use a reverser with a built-in breaker, like the NCE AR10 or PSX-AR.

  4. 4

    Don't stack devices

    NCE says to keep other track power devices, like breakers or frog juicers, out of line before or after the AR10. Feed it straight from the system.

  5. 5

    Use a dual frog juicer as a reverser

    Tam Valley's Dual Frog Juicer can work as a reverser when you put its Pair Outputs jumper on. It's a low-cost way to handle a simple loop.

Watch how it's done

The Truth About Autoreversers, Circuit Breakers and Frog JuicersModel Railroading
Reversing Loops With Digitrax AR1Richard Foster
I Solved My Reverse Loop Problems With This One PSX CV SettingThe Nearly Historical
Configuring a PSX-AR With a Digitrax SystemPractical Engineering
Protect Your Trains With the Frog-AR and PSXXModel Railroading
Installing an Auto Reverser on a DCC Reversing LoopDonegal Dad-Rail

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5A Wi-Fi/DCC Booster with Auto Reverse and Variable Track VoltageWifiTrax5A Wi-Fi/DCC Booster with Auto Reverse and Variable Track Voltage$115.00In stockLoDi-KSM-P · Reverse Loop Module · Z to G · LoDi012PLokstoredigitalLoDi-KSM-P · Reverse Loop Module · Z to G · LoDi012P$68.49In stockEZ-Track · 9" Straight Electronic Auto-Reversing Track · HO Scale 44548BachmannEZ-Track · 9" Straight Electronic Auto-Reversing Track · HO Scale 44548$41.33In stockEZ-Track · N Scale Nickel Silver Auto-Reversing 5" Straight Track 44848BachmannEZ-Track · N Scale Nickel Silver Auto-Reversing 5" Straight Track 44848$42.05In stockEZ-Track · 18" Radius Curved Electronic Auto Reversing · HO Scale 44549BachmannEZ-Track · 18" Radius Curved Electronic Auto Reversing · HO Scale 44549$41.33In stockG Scale · MTS Reverse Loop ModuleLGBG Scale · MTS Reverse Loop Module$156.75In stockEZ-Track · N Scale · Auto Reversing 11.25" Radius Curved TrackBachmannEZ-Track · N Scale · Auto Reversing 11.25" Radius Curved Track$42.05In stockHO Scale · E-Z Track Electronic Auto-Reversing SystemBachmannHO Scale · E-Z Track Electronic Auto-Reversing System$188.50In stock
← Power Districts & Circuit BreakersNext: Boosters: Common Ground vs Opto-Isolated →
Advanced DCC Wiring · Guide 10 of 18

Advanced DCC Wiring

Boosters: Common Ground vs Opto-Isolated

Each booster powers its own district. Where two boosters meet, a loco briefly bridges both, so the boosters must agree on voltage, phase and a shared reference. How you connect them depends on whether your boosters share a common ground or have opto-isolated inputs.

AdvancedWhen you run more trains at once6 videos

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Boosters DCC Power Supplies Cables & Connectors Wire & Accessories

Step by step

  1. 1

    Add boosters for trains, not space

    Count the locos running at the same time, sound locos idling in the yard included. Allan's rule of thumb: a 5-amp booster runs six to eight HO locos.

  2. 2

    Gap both rails between booster districts

    Never connect booster outputs together, and never use a common rail between booster districts. Both cause ground loops and shorts.

  3. 3

    Common ground boosters: add a booster common

    NCE and Digitrax boosters use a floating common. Run a heavy wire (about the size of your bus) between the boosters' cases or ground terminals and the command station. Never connect it to earth or house ground.

  4. 4

    Digitrax: watch LocoNet pins 2 and 5

    LocoNet also carries ground on pins 2 and 5. Allan Gartner suggests cutting those wires in the booster network cable, at one end only, after the heavy common wire is in. Leave them alone in the throttle network.

  5. 5

    Opto-isolated boosters for common rail

    If the layout is wired common rail, use boosters with opto-isolated control inputs (like the Digitrax DB210-OPTO), give each booster its own power supply, skip the booster common wire, and never use the booster's auto-reverse feature.

  6. 6

    Phase and voltage check

    Run a loco across each booster gap. If it stutters or trips, swap that booster's two track wires. Set every booster to the same track voltage. NCE aims for about 14 V in HO and 12 V in N.

Go deeper on Wiring for DCC

Watch how it's done

Wiring Your Model Railroad for DCC: BoostersModel Railroading
The Truth About DCC Command Stations and BoostersModel Railroading
Need More DCC Power? Watch This Before You BuyModel Railroading
Booster Challenge: 20 Sound Locomotives!Iron Planet Hobbies
Affordable Boosters for the ESU ECoSIron Planet Hobbies
Expanding a Digitrax System With a PS-2012E, DB220 and PM74sGreat Northern Cascade

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DB210 Single 3/5/8 Amp BoosterDigitraxDB210 Single 3/5/8 Amp Booster$127.98In stockDB220 Dual 3/5/8 Amp BoosterDigitraxDB220 Dual 3/5/8 Amp Booster$192.78In stockDB210-OPTO Single 3/5/8 Amp BoosterDigitraxDB210-OPTO Single 3/5/8 Amp Booster$129.23In stockDB210 Bundle - Single 3/5/8 Amp Booster With Power SupplyDigitraxDB210 Bundle - Single 3/5/8 Amp Booster With Power Supply$169.99In stock3.5 Amp LocoNet & CDE DCC Booster · Works With All BrandsYaMoRC3.5 Amp LocoNet & CDE DCC Booster · Works With All Brands$143.45In stockCobalt Alpha Box · 5 Amp DCC Booster · DCD-AUXDCCconceptsCobalt Alpha Box · 5 Amp DCC Booster · DCD-AUX$134.80In stockDCC LCC Booster · 15 VoltTCSDCC LCC Booster · 15 Volt$239.95 $232.72In stockECoSBoost ext. Booster 7 Amp MM/DCC/SX/M4 With Power SupplyESUECoSBoost ext. Booster 7 Amp MM/DCC/SX/M4 With Power Supply$231.20In stock
← Auto ReversersNext: Block Detection →
Advanced DCC Wiring · Guide 11 of 18

Advanced DCC Wiring

Block Detection

A block detector sees current flowing in a section of track and reports it as occupied. Signals, CTC panels, grade crossings and automation all start here. Plan your gaps and sub-buses while you build, because adding them later means rewiring.

AdvancedBest planned before track goes down6 videos

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Detection Power Management Wire & Accessories

Step by step

  1. 1

    Decide where the blocks go

    Typical blocks run between signals or between turnouts. Allan Gartner's advice: gap the rails and run the sub-buses when you build. Adding detectors later is easy. Adding gaps is not.

  2. 2

    Gap one rail per block

    Most current-sensing detectors watch one rail. Gap that rail at each end of the block and feed it through the detector. The other rail stays common within that booster district.

  3. 3

    Wire the detector close to its block

    Keep the wire from the detector to the track short and untwisted, or stray capacitance can show the block as occupied when it isn't.

  4. 4

    Make cars visible

    Locomotives draw current, but cars don't. Add resistor wheelsets or resistors across an axle to cabooses and the last car. Use the maximum value your detector's manual allows. Allan used 10K ohms on his.

  5. 5

    Report it to your system

    Detectors report over LocoNet, Cab Bus (through an AIU), LCC or to a computer running JMRI. RailCom and transponding detectors can also tell you which loco is in the block.

Go deeper on Wiring for DCC

Watch how it's done

Block Detection for Your Model RailroadModel Railroading
Introducing the BD4N 4-Block Occupancy DetectorDigitrax
Make Your Own Detector WheelsetsModel Railroading
Setup for RailCom & Block Detection With JMRIIron Planet Hobbies
Easy NCE RailCom Setup, Part 1Iron Planet Hobbies
An Intro to Block DetectionChadwick Model Railway

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BD20 · Block DetectorNCEBD20 · Block Detector$15.56In stockBD4N Occupancy Detector For 4 Detection SectionsDigitraxBD4N Occupancy Detector For 4 Detection Sections$30.34In stock(Replaces BDL168)Digitrax(Replaces BDL168)$90.20In stockBXP88 8 Occupancy Feedback Detector SectionsDigitraxBXP88 8 Occupancy Feedback Detector Sections$147.60In stockLCC BOD4 · Block Occupancy Detector · 4 BlocksRR-CirKitsLCC BOD4 · Block Occupancy Detector · 4 Blocks$29.84In stockDCC Block Watcher Block DetectorDCC SpecialtiesDCC Block Watcher Block Detector$35.95In stockLocoNet 16 Channel Feedback Module · Current Sensing InputsYaMoRCLocoNet 16 Channel Feedback Module · Current Sensing Inputs$112.25In stockLCC BOD4-CP · Block Occupancy Detector & Dual Turnout BOD-4-CP · 4 BlocksRR-CirKitsLCC BOD4-CP · Block Occupancy Detector & Dual Turnout BOD-4-CP · 4 Blocks$42.80In stock
← Boosters: Common Ground vs Opto-IsolatedNext: Signaling →
Advanced DCC Wiring · Guide 12 of 18

Advanced DCC Wiring

Signaling

Signals take three things: detection to know where trains are, logic to decide what each signal shows, and drivers to light the heads. You can do it with simple stand-alone boards, a LocoNet or LCC system, or a computer running JMRI.

AdvancedPlan early, install late6 videos

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Signals Signal Electronics Detection LCC

Step by step

  1. 1

    Pick a system to model

    ABS (automatic block signals) shows red, yellow or green based on the blocks ahead. APB adds protection for opposing moves on single track. CTC lets a dispatcher set routes and signals from a panel.

  2. 2

    Detect every block

    Each signal needs to know whether the block ahead is occupied, and often the block after it too. That means a detector on every block it protects.

  3. 3

    Feed in turnout positions

    A signal at a turnout should change with the route. Wire the switch machine's spare contacts, or use a stationary decoder that reports position.

  4. 4

    Choose the logic

    Stand-alone signal boards, Digitrax's SE74 on LocoNet, RR-CirKits' SignalMan on LCC, or JMRI on a computer. Allan Gartner chose LCC for his own layout, and it runs without a computer.

  5. 5

    Mount and wire the heads

    Plan signal spots before scenery goes in, and keep clear of switch machines under the track. Bring cables to a terminal strip near each signal.

Go deeper on Wiring for DCC

Watch how it's done

ABS Signals for Your Model RailroadModel Railroading
Easy Signal Wiring for DCCModel Railroading
Easy Signals for Your Model RailroadModel Railroading
Why Are Railroad Signals Red, Green and Yellow?Model Railroading
Model Railroad Signaling Intro Clinic: Exploring LCCBurr Stewart
Digitrax SE74 Explained: Signal WiringJim Worcester

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LocoNet Signal Decoder & Turnout ControlDigitraxLocoNet Signal Decoder & Turnout Control$97.58In stockSignalMan-S · Screw Terminals · 16 Signal LEDsRR-CirKitsSignalMan-S · Screw Terminals · 16 Signal LEDs$47.96In stockLight-It Universal Lighting & Signal Decoder · 6-PackNCELight-It Universal Lighting & Signal Decoder · 6-Pack$36.62In stock16 Channel DCC Signal & Turnout DecoderYaMoRC16 Channel DCC Signal & Turnout Decoder$91.03In stockHO Scale Turnout Signaling Kit · 3 Signals & HardwareDigitraxHO Scale Turnout Signaling Kit · 3 Signals & Hardware$22.14In stockN Scale Turnout Signaling Kit · 4 Signals & HardwareDigitraxN Scale Turnout Signaling Kit · 4 Signals & Hardware$22.14In stockSSSB-S Dual Head · Signal Decoder/DriverRR-CirKitsSSSB-S Dual Head · Signal Decoder/Driver$9.40In stockHO / N Scale · UniTrack Extension Cord Automatic 3-Color Signal · (1 pc)KatoHO / N Scale · UniTrack Extension Cord Automatic 3-Color Signal · (1 pc)$2.50In stock
← Block DetectionNext: ABC Braking: Stop at Signals →
Advanced DCC Wiring · Guide 13 of 18

Advanced DCC Wiring

ABC Braking: Stop at Signals

ABC (Automatic Brake Control, often called ABS braking) was developed by Lenz. A braking module makes the DCC signal slightly uneven in one track section. Decoders that support ABC notice and brake smoothly to a stop. Locos without ABC just keep running normally.

AdvancedAny time6 videos

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Power Management Decoders HO Joiners & Accessories

Step by step

  1. 1

    Check your decoders

    Lenz Standard+ V2, Silver+ and Gold+ (and older Gold and Silver), ESU LokSound and LokPilot V4 and newer, all Zimo decoders and DCCconcepts Zen Black support ABC. Turn the feature on in the decoder's CVs.

  2. 2

    Cut a braking section

    Gap one rail ahead of the signal for the stopping section. Allow room to slow down, plus some extra.

  3. 3

    Install the braking module

    Lenz BM1 (stop), BM2 (slow approach plus stop) and BM3 (automatic blocks) or DCCconcepts' ABC modules feed the section. Most connect to a signal contact or a switch: red means asymmetric (stop), green means normal.

  4. 4

    Tune the stop

    Set the braking distance in the decoder. Many decoders support constant braking distance, so every loco stops at the same spot whatever its speed.

  5. 5

    Make sure the booster is clean

    ABC needs a symmetrical DCC signal from the booster. ESU warns that some older boosters distort it and stop ABC working.

Watch how it's done

Lenz ABC BrakingDCCtrainautomation
DCC ABC Braking: Introduction and DemoMegapoints Controllers
Lenz ABC Braking, Film 1A&H Models
Lenz ABC Braking, Film 3: BM2 ModuleA&H Models
Decoder Setup for Constant Distance ABC BrakingDongits Model Railway
Automatic Brake Control: Easy AutomationLittle Wicket Railway

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Pack of 3 ABC Slow or Stop ModulesDCCconceptsPack of 3 ABC Slow or Stop Modules$37.29In stockABC Slow or Stop Modules · 6 PiecesDCCconceptsABC Slow or Stop Modules · 6 Pieces$72.56In stockLokPilot 5 Basic · 21 Pin DCC Decoder · RailComESULokPilot 5 Basic · 21 Pin DCC Decoder · RailCom$23.92In stockV5 Micro DCC Decoder · Direct Kato USA WidebodyESUV5 Micro DCC Decoder · Direct Kato USA Widebody$103.99In stockLokPilot 5 Nano · E24 DCC Motor Decoder · Fits New AtlasESULokPilot 5 Nano · E24 DCC Motor Decoder · Fits New Atlas$32.72In stockZen Black DCC Decoder · 21 Pin MTC With 8 Pin Harness · 6 Full Power Functions · 3 ABC ModulesDCCconceptsZen Black DCC Decoder · 21 Pin MTC With 8 Pin Harness · 6 Full Power Functions · 3 ABC Modules$62.19In stockTrack Bus Terminal Tags · 50 Pack · DCC-Tag50DCCconceptsTrack Bus Terminal Tags · 50 Pack · DCC-Tag50$17.58In stock18V DC, 2A (US) · DC/DCC systems – 2.5mm DC plugDCCconcepts18V DC, 2A (US) · DC/DCC systems – 2.5mm DC plug$31.07In stock
← SignalingNext: Shuttle Trains & Simple Automation →
Advanced DCC Wiring · Guide 14 of 18

Advanced DCC Wiring

Shuttle Trains & Simple Automation

A shuttle runs a train from one end of a line to the other, pauses, and comes back, over and over. It's perfect for trolleys, branch lines and show layouts. With DCC you can build the brains into the decoder, the command station or a computer.

IntermediateAny time5 videos

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Power Management Detection Command Stations Decoders

Step by step

  1. 1

    Decoder shuttle with ABC

    Some decoders can shuttle on their own. Put an ABC braking module at each end of the line. The loco slows, stops, waits, then reverses. ESU LokSound 5 has an automatic ABC shuttle, and DCCconcepts Zen Black decoders have advanced shuttle control built in.

  2. 2

    Command station shuttle

    ESU's ECoS runs up to eight shuttle trains. Put an occupancy detector at each end of the track and set wait time, speed and stops on the screen. It works with any decoder.

  3. 3

    Computer automation

    JMRI and other layout software can run shuttles, timetables and whole routes using block detectors.

  4. 4

    Keep both ends safe

    Add an end-of-track bumper and leave margin past each stopping point, in case a loco overruns.

Go deeper on Wiring for DCC

Watch how it's done

How to Install a DCC Shuttle Train on Your RailwayThat Model Railway Guy
How to Add a Zen Black DCC Shuttle ModuleJennifer E. Kirk Model Railways
DCCconcepts Zen Black ShuttleLayout Concepts
Easy ABC Shuttle SystemJennifer E. Kirk Model Railways
DCC Shuttle System With ABC BrakingDoug Bull

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Zen Black Shuttle Pack · Includes Zen Black O & Large Scale “Buddha” DCC Decoder + 3 ABC ModulesDCCconceptsZen Black Shuttle Pack · Includes Zen Black O & Large Scale “Buddha” DCC Decoder + 3 ABC Modules$103.76In stockECoS · DCC Command Station · Color Screen · 7A Power SupplyESUECoS · DCC Command Station · Color Screen · 7A Power Supply$719.20In stockAutomatic Reversing Shuttle For Analog · PIKO & LGBMassothAutomatic Reversing Shuttle For Analog · PIKO & LGB$109.92 $92.16In stockG Scale Shuttle Train Automatic Circuit Box (1 pc) 10345LGBG Scale Shuttle Train Automatic Circuit Box (1 pc) 10345$170.99In stockDT-4 Bi-Directional Rolling Stock DetectorCircuitronDT-4 Bi-Directional Rolling Stock Detector$45.49In stockCT-Coil-Set-6 · For BOD · 6 pcsRR-CirKitsCT-Coil-Set-6 · For BOD · 6 pcs$10.23In stockCT-Coil-Set-4 · For BOD · 4 pcsRR-CirKitsCT-Coil-Set-4 · For BOD · 4 pcs$8.00In stockAIU01 Auxiliary Input UnitNCEAIU01 Auxiliary Input Unit$51.24In stock
← ABC Braking: Stop at SignalsNext: LocoNet (Digitrax) →
Throttle & Layout Networks · Guide 15 of 18

Throttle & Layout Networks

LocoNet (Digitrax)

LocoNet is the network Digitrax uses for throttles, boosters, detectors, signal and turnout decoders, and computer interfaces. Many other brands, like YaMoRC, Digikeijs, RR-CirKits and ESU's converter, speak it too.

IntermediateDigitrax and LocoNet systems6 videos
Comparing networks? See the Network Cheat Sheet.

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Cables & Connectors Universal Panels Throttles Receivers & Wi-Fi

Step by step

  1. 1

    Use flat 6-wire cable

    Digitrax recommends flat six-conductor telephone cable with RJ12 6P6C plugs. Shielded twisted pair, like Cat5, actually hurts LocoNet performance.

  2. 2

    Know the pins

    Pins 2 and 5 are ground, 3 and 4 carry LocoNet data, and 1 and 6 carry RailSync, a copy of the track signal that boosters use.

  3. 3

    Wire it any shape except a ring

    Star, tee and branch are all fine. Never loop LocoNet back on itself. That shorts the RailSync lines.

  4. 4

    Stay within the length limits

    About 2000 ft of cable in total, and no more than 1000 ft between any two devices. Only the command station provides termination.

  5. 5

    Add panels and Wi-Fi

    Universal panels (UP7) put throttle jacks on the fascia. An LNWI adds phone throttles through WiThrottle and Engine Driver apps.

Go deeper on Wiring for DCC

Watch how it's done

DCC Basics: What Are All These Wires For?Model Railroading
Making a LocoNet Cable for Digitrax DCC Systemsck7813
Making LocoNet Cables the Easy WayToms Trains and Things
How to Add an Extra Digitrax UP5 to Your LocoNetmpeterll
LNWI Quickstart and Android Device SetupDigitrax
How to Add a Real Wi-Fi Throttle to Your Digitrax SystemIron Planet Hobbies

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LNC82 8 Foot LocoNet Cables With End Connectors Installed (2 pcs)DigitraxLNC82 8 Foot LocoNet Cables With End Connectors Installed (2 pcs)$9.84In stockLocoNet Cable Maker KitDigitraxLocoNet Cable Maker Kit$44.28In stockLNRJ12P20 RJ12 Plugs-20 PackDigitraxLNRJ12P20 RJ12 Plugs-20 Pack$9.84In stockLNWI LocoNet WiFi InterfaceDigitraxLNWI LocoNet WiFi Interface$68.06In stockLocoBuffer-NG · Next Generation LocoBuffer · LB-NGRR-CirKitsLocoBuffer-NG · Next Generation LocoBuffer · LB-NG$55.16In stockLNCCMC1 Coiled LocoNet Cord With Modular AdapterDigitraxLNCCMC1 Coiled LocoNet Cord With Modular Adapter$14.76In stock21 Pin 21MTC Adapter Board 3 With 200mm Wires & Amplifier · 8 OutputsESU21 Pin 21MTC Adapter Board 3 With 200mm Wires & Amplifier · 8 Outputs$12.39In stockRJ12 6pin Curly Cord For NCE Power Cab & Cobalt Alpha · DCD-ACLDCCconceptsRJ12 6pin Curly Cord For NCE Power Cab & Cobalt Alpha · DCD-ACL$12.94In stock
← Shuttle Trains & Simple AutomationNext: NCE Cab Bus →
Throttle & Layout Networks · Guide 16 of 18

Throttle & Layout Networks

NCE Cab Bus

Cab Bus links NCE throttles, fascia panels and accessories like the AIU to the command station. It's an RS-485 bus that runs as one continuous daisy chain, so the rules differ from LocoNet.

IntermediateNCE systems5 videos
Comparing networks? See the Network Cheat Sheet.

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Cables & Connectors Universal Panels Throttles Receivers & Wi-Fi

Step by step

  1. 1

    Run one daisy chain

    Cab Bus should be a continuous chain from panel to panel, up to 1000 ft, with no branches longer than about 20 ft.

  2. 2

    Use the right cable

    RJ12 plugs, with the center four wires used. The flat 6-wire cable for the Power Cab carries track power as well as the bus. NCE says to use only their cable for that job.

  3. 3

    Plan cab addresses

    A Power Pro system supports up to 63 cab addresses, including accessories like the AIU and USB interface. The Power Cab supports up to 4 cabs.

  4. 4

    Keep the voltage up

    Cabs need at least 8 V DC on the bus, measured between pins 2 and 5. Long, thin cables drop voltage.

  5. 5

    Boosters use the control bus

    NCE boosters connect over a separate 4-wire control bus cable (RJ-H/RJ9) that can run up to 300 ft.

Go deeper on Wiring for DCC

Watch how it's done

NCE Cab Bus, Part 1arthurhouston3
Install an NCE PowerCab DCC SystemModel Railroading
Wi-Fi Throttles for Your NCE PowerCabModel Railroading
NCE Power Cab Simple Wi-Fi Addition Without JMRIIron Planet Hobbies
TCS UWT-100 Throttle Setup on NCE Without JMRIIron Planet Hobbies

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UTP · Panel Cab Bus Fascia Panel w/RJ12 PlugsNCEUTP · Panel Cab Bus Fascia Panel w/RJ12 Plugs$25.60In stockUTP-CAT5 · Cab Bus Fascia Panel With CAT5 Rear ConnectionsNCEUTP-CAT5 · Cab Bus Fascia Panel With CAT5 Rear Connections$27.07In stockRJ12-7 · 6 Wire Straight Cab Bus Cable · 7 FeetNCERJ12-7 · 6 Wire Straight Cab Bus Cable · 7 Feet$7.29In stockRJ12-12 · 6 Wire Straight Cab Bus Cable · 12 FeetNCERJ12-12 · 6 Wire Straight Cab Bus Cable · 12 Feet$8.75In stockNCE Cab Bus Wi-Fi Interface Module · WiThrottle ServerWifiTraxNCE Cab Bus Wi-Fi Interface Module · WiThrottle Server$112.23In stockProCab · Wired Handheld DCC Cab Throttle With Cable, BacklitNCEProCab · Wired Handheld DCC Cab Throttle With Cable, Backlit$179.99In stockCab06 · Power Pro Cab/LED Display/Digital EncoderNCECab06 · Power Pro Cab/LED Display/Digital Encoder$101.36In stock8 Wire Adapter Converts 6 Wire · RJ12 Cab Bus To 8 Wire RJ45NCE8 Wire Adapter Converts 6 Wire · RJ12 Cab Bus To 8 Wire RJ45$10.10In stock
← LocoNet (Digitrax)Next: XpressNet & Multi-Bus Systems →
Throttle & Layout Networks · Guide 17 of 18

Throttle & Layout Networks

XpressNet & Multi-Bus Systems

XpressNet is Lenz's throttle network, also used in Roco and other European-style systems. Multi-bus command stations like the YaMoRC YD7010 and Digikeijs DR5000 speak XpressNet, LocoNet and other buses at the same time, so you can mix throttle brands.

IntermediateLenz, Roco and multi-bus systems5 videos
Comparing networks? See the Network Cheat Sheet.

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Command Stations Cables & Connectors Throttles

Step by step

  1. 1

    Know the basics

    XpressNet is an RS-485 bus running at 62.5 kBaud. The command station gives each connected device a time slot.

  2. 2

    Wire it as a bus

    Lenz says the wires shouldn't be thinner than 0.25 mm², and 0.5 mm² or larger is better.

  3. 3

    Give every device its own address

    Each throttle or interface needs a unique XpressNet address.

  4. 4

    Mix throttles on a multi-bus station

    A multi-bus command station can take LocoNet, XpressNet and other throttles at once. It's a good way to keep the throttles you already own.

Go deeper on Wiring for DCC

Watch how it's done

Digikeijs DR5000 DCC Command StationIron Planet Hobbies
Using Several Brands of Throttles With the DR5000Buckambool Model Trains
DR5000 With 4 Separate Throttle InputsJeff Shultz
Roco WLANmaus Throttle Setup for the DR5000Iron Planet Hobbies
DR5000 on JMRI, Wired and WirelessIron Planet Hobbies

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WiFi / LAN Module to Replace a Digikeijs DR5000's RM04YaMoRCWiFi / LAN Module to Replace a Digikeijs DR5000's RM04$86.03In stockLocoNet / XpressNet / Cab Bus / R-Bus Cable · 6-Pin · 6m / 19.7'DigikeijsLocoNet / XpressNet / Cab Bus / R-Bus Cable · 6-Pin · 6m / 19.7'$7.72In stockLocoNet / R-Bus / XpressNet Cable · 3m / 9.8'DigikeijsLocoNet / R-Bus / XpressNet Cable · 3m / 9.8'$4.99In stockLocoNet / XpressNet / Cab Bus / R-Bus Cable · 6-Pin · 7m / 23'DigikeijsLocoNet / XpressNet / Cab Bus / R-Bus Cable · 6-Pin · 7m / 23'$9.49In stockDiMAX · Receiver For Navigator With XpressNet & LocoNetMassothDiMAX · Receiver For Navigator With XpressNet & LocoNet$137.23In stockThe Integrator · LocoNet For ESU ECoS, CabControl & CS1 50097ESUThe Integrator · LocoNet For ESU ECoS, CabControl & CS1 50097$79.92In stock18 Pin Next18 Socket to Open Wires · 88mm · With Heat Shrink TubeESU18 Pin Next18 Socket to Open Wires · 88mm · With Heat Shrink Tube$6.79In stock9 Pin To 8 Pin Wire Short Harness (1 pc)Digitrax9 Pin To 8 Pin Wire Short Harness (1 pc)$6.56In stock
← NCE Cab BusNext: LCC: Layout Command Control →
Throttle & Layout Networks · Guide 18 of 18

Throttle & Layout Networks

LCC: Layout Command Control

LCC is an NMRA standard network for everything that isn't a locomotive: signals, turnouts, block detection, buttons and lights. Taking that traffic off the DCC bus keeps loco commands fast, and LCC nodes talk to each other directly, with no computer required.

AdvancedSignals, panels and automation6 videos
Comparing networks? See the Network Cheat Sheet.

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LCC RR-CirKits LCC TCS LCC Detection

Step by step

  1. 1

    Learn the parts

    Nodes are the boards that do the work (inputs, outputs, signals, detectors). They link with CAT5-style cables on a CAN bus.

  2. 2

    Terminate both ends

    The LCC bus runs node to node and needs a terminator at each end.

  3. 3

    Configure, don't program

    You set up nodes with a configuration tool like JMRI. Events link an input, like a button or detector, to outputs, like a turnout or signal.

  4. 4

    Bridge to your DCC system

    Interfaces let LCC work alongside Digitrax, NCE and others. TCS shows LCC with both Digitrax and NCE systems.

  5. 5

    Start small

    One Tower LCC node, a few buttons and a turnout make a great first project. Add signals and detection later.

Go deeper on Wiring for DCC

Watch how it's done

What Is LCC? Explained!TCSDCC
What Does LCC Actually Do?TCSDCC
NMRA LCC Layout OverviewTCSDCC
Integrating TCS LCC With a Digitrax SystemTCSDCC
Integrating TCS LCC With an NCE SystemTCSDCC
Introduction to Layout Command Control4DPNR Movies

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← XpressNet & Multi-Bus SystemsWire Size Finder →

Where to Start

  1. 1
    Basic DCC WiringStart here. Power, bus and feeders, turnouts, reverse loops and a programming track: everything a first DCC layout needs.How DCC Power WorksTrack Bus & FeedersThe Quarter Test & Finding ShortsDCC-Friendly Turnouts & FrogsReverse Loops, Wyes & TurntablesProgramming TrackTurnout Control & Stationary Decoders
  2. 2
    Advanced DCC WiringPower districts, auto reversers, more boosters, detection, signals, automatic braking and shuttles.Power Districts & Circuit BreakersAuto ReversersBoosters: Common Ground vs Opto-IsolatedBlock DetectionSignalingABC Braking: Stop at SignalsShuttle Trains & Simple Automation
  3. 3
    Throttle & Layout NetworksThe cables that connect throttles, panels and accessories: LocoNet, Cab Bus, XpressNet and LCC.LocoNet (Digitrax)NCE Cab BusXpressNet & Multi-Bus SystemsLCC: Layout Command Control

Free tool

Wire Size Finder

Pick your scale, booster size and how far the bus runs from the booster to the farthest track. You'll get bus and feeder sizes, feeder spacing and what to do on long runs.

Scale
Booster
30 ft

Bus and feeder size ranges and feeder spacing are Allan Gartner's suggestions from Wiring for DCC. Voltage drop is simple math: booster amps × copper wire resistance × the out-and-back length. We highlight the lightest wire in Allan's range that stays under 1 volt of drop; heavier wire is always fine. Always finish with the quarter test.

Track Plan Check: Do I Need a Reverser?

If a train can leave a spot and come back facing the other way, one rail meets the other somewhere and you need a reversing section. The orange piece in each drawing is a good place for it: gapped in both rails and longer than your longest train.

Simple ovalNo reverser
Oval with sidingsNo reverser
Point to pointNo reverser
Balloon (reverse) loopReverser needed
WyeReverser needed
TurntableReverser needed
Dogbone with crossoverReverser needed
Oval with a diagonalReverser needed

Next step: Reverse Loops, Wyes & Turntables and Auto Reversers.

Network Cheat Sheet

Throttle networks (LocoNet, Cab Bus, XpressNet) carry throttles and system devices. LCC is a separate layout network for signals, turnouts and detection. From Digitrax, NCE, Lenz and NMRA documentation.

LocoNetNCE Cab BusXpressNetLCC
Used byDigitrax, plus YaMoRC, Digikeijs, RR-CirKits and othersNCE (also older Wangrow and PSI Dynatrol systems)Lenz, Roco and multi-bus stationsNMRA standard: RR-CirKits, TCS and others
JobThrottles, boosters, detection, accessoriesThrottles, panels, AIU and USBThrottles and accessoriesSignals, turnouts, detection, lights
CableFlat 6-wire, RJ12 6P6CRJ12 (center 4 wires); NCE flat 6-wire for Power CabBus cable, at least 0.25 mm²CAT5-style cable
LayoutFree-form: star, tee, branch. Never a ringOne daisy chain, branches under ~20 ftBusNode to node, terminator at each end
Length~2000 ft total, ≤1000 ft between devicesUp to 1000 ftFollow Lenz's wiring guideSee node maker's guide
DevicesMany (power-hungry ones need their own supply)Up to 63 cab addresses (Power Cab: 4)One address per deviceMany nodes
LocoNet guide →Cab Bus guide →XpressNet guide →LCC guide →
Proud sponsor of

Wiring for DCC

For nearly 30 years, Allan Gartner has answered model railroaders' DCC wiring questions for free at WiringForDCC.com: bus and feeders, turnouts, reversing sections, boosters, block detection, signaling and LCC, with hundreds of diagrams. It's the reference we send customers to, and much of the advice on this page comes from it.

Iron Planet Hobbies is proud to sponsor Allan's site. If it helps you, tell him we sent you.

Visit WiringForDCC.com ↗Ask on the DCC Q&A Forum ↗Allan's book: DCC and Model Railroading ↗

DCC Wiring Words, Made Simple

Bus
The heavy pair of wires under the layout that carries track power from the booster.
Feeder
A short wire from the bus up to the rail.
Booster
Turns the command station's signal into track power. Each booster powers its own district.
Power district
A section of track with its own short-circuit protection: a booster or a circuit breaker.
Reversing section
Track where a train can turn around. Needs gaps in both rails and polarity switching.
Frog
The point where two rails cross in a turnout. Plastic (dead) or metal (powered).
Snubber
A resistor plus capacitor across the far end of a long bus, to calm voltage spikes.
Stationary decoder
A decoder for turnouts, signals or lights instead of a locomotive.
Opto-isolated
A booster input that's electrically separate from the booster's output, needed for common-rail wiring.
CV
Configuration Variable: a numbered setting inside a decoder.

Stuck on a Wiring Problem?

Tell us your system and what's happening, and we'll help you find the fix and the right parts. Call 833-322-4373 or send us a message.

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DCC Wiring FAQ

What size wire should I use for a DCC bus?

Allan Gartner's Wiring for DCC suggests 16–14 AWG for Z and N, 16–12 AWG for HO, and 14–10 AWG for S, O and G. Heavier is always fine. The real test: shorting the track at the far end must trip the booster (the quarter test).

How often do I need track feeders?

About every 10 ft for code 100 rail and every 6 ft for code 83 and smaller. In N and Z, every 3 to 6 ft. If joiners aren't soldered, or the rail is weathered, put a feeder on every piece of rail.

What is the quarter test?

Lay a coin across the rails anywhere on the layout. The booster or circuit breaker must shut off right away, every time, everywhere. If it doesn't, the wiring is too weak and a short could overheat something.

Do I need blocks with DCC?

Not like DC cab blocks. You only need gaps for reversing sections, block detection, power districts and boosters. A few sections still make finding shorts much easier.

Why does my layout short when a train enters a loop or wye?

That track is a reversing section: one rail meets the other. Gap both rails at both ends, make it longer than your longest train, and add an auto reverser or a polarity switch.

Do I need DCC-friendly turnouts?

They make life easier. On a DCC-friendly turnout the point rails always match the stock rails, and the frog is isolated, so wheels can't short across the points. Powered frogs then need a switch, relay or frog juicer to set polarity.

When do I need a second booster?

When you run more trains at once than one booster can handle, not because the layout is big. Allan Gartner's rule of thumb: a 5-amp booster runs six to eight HO locomotives.

What's the difference between common-ground and opto-isolated boosters?

Common-ground boosters (most NCE and Digitrax) need a heavy booster common wire between them and gaps in both rails between districts. Opto-isolated boosters are for common-rail layouts: no booster common wire, a separate power supply for each booster, and never use the booster's auto-reverse feature.

Can I mix LocoNet, Cab Bus and XpressNet?

Not directly: each is its own network. Multi-bus command stations and some interfaces can connect more than one, and Wi-Fi throttle apps work with most systems through WiThrottle.

Where can I buy DCC wiring supplies?

Every guide on this page links to the matching Iron Planet Hobbies categories, with in-stock picks from Digitrax, NCE, Tam Valley Depot, DCC Specialties, RR-CirKits, DCCconcepts, ESU, TCS and more.

Guides written by Iron Planet Hobbies from Allan Gartner's Wiring for DCC and the manufacturers' published instructions (Digitrax, NCE, Lenz, ESU, TCS, Tam Valley Depot, DCC Specialties, NMRA), linked in each guide. Always follow the instructions that come with your equipment. Videos play from their creators' YouTube channels. Product names belong to their manufacturers. Prices and stock checked October 30, 2026.

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