Wiring
How to Solder Rail Feeders
Quick answer
Solder a feeder wire to the outside web of the rail, not the top of the railhead, at least every 3 feet of track, because a rail joiner is a mechanical connection rather than a reliable electrical one and a layout wired through joiners alone develops dead sections within a year or two.
A rail joiner does one job well: it holds two pieces of rail in line with each other. It was never designed as a long-term electrical connector, and treating it as one is the single most common reason a layout that ran perfectly on the workbench develops mysterious stalls and flickering lights a year after it was finished. Joiners loosen with seasonal wood movement, oxidize slightly at the contact surface, and shift as track ages, all of which quietly raise their electrical resistance without ever fully disconnecting the rail.
Feeders solve this permanently. This guide covers how many you need, where they go, and how to solder them without damaging the track around them.
On this page
Why a rail joiner is not enough on its own
A rail joiner is a stamped metal sleeve that slides over the ends of two adjoining rails and holds them aligned. That mechanical fit is genuinely good at keeping wheels from dropping at a joint, and genuinely poor at guaranteeing current passes through it at a low, stable resistance for years. Track expands and contracts slightly with temperature and humidity, benchwork flexes a small amount even when built well, and every one of those tiny movements works a joiner's grip on the rail a little looser over time. The failure is not sudden. It shows up as a locomotive that hesitates at one specific spot, or a string of track-powered lights that flicker there, months or years after the layout was finished and long after anyone remembers exactly how that section was wired.
How often to feed the rail
A feeder every three feet is the practical minimum most layouts should treat as a hard floor, not an aspirational target.
A feeder every 3 feet of rail is the practical minimum for reliable power, and a feeder soldered to every individual piece of flex track is better still where the budget for wire and time allows it.
| Approach | Feeder spacing | Result |
|---|---|---|
| Joiners only, no feeders | None | Reliable at first, develops dead sections within a year or two |
| Minimum practical spacing | Every 3 feet | Reliable for typical HO and N layouts |
| Every piece of rail fed | Every flex track section | The counsel of perfection, and the most reliable option |
Longer or higher-current buses may want closer spacing; check the bus wire gauge calculator for your actual run.
Steps to solder a rail feeder
- Strip a short length of feeder wire. 22 AWG wire such as BNTECHGO 22 AWG Silicone Wire Red and Black 250 ft Stranded Tinned Copper is a common, easy-to-work choice for feeders on typical HO and N layouts.
- Clean and tin the rail web. Lightly scuff the outside web of the rail, below the railhead where it will not be seen, and apply a small amount of solder so the iron only has to touch the joint briefly afterward.
- Tin the stripped wire end. A pre-tinned wire end bonds faster once it touches the rail, which shortens the time the iron spends near the ties.
- Solder the wire to the rail web quickly. Touch the tinned wire to the tinned rail spot and apply heat briefly. A joint that will not take within a couple of seconds usually means the surfaces were not clean, not that more heat is the fix.
- Keep heat away from the ties. Plastic ties melt and deform under sustained heat. Working quickly on already-tinned surfaces, and pulling the iron away the instant the joint flows, avoids this entirely.
- Route the feeder down through the roadbed. A small drilled hole under the rail lets the feeder drop straight down to the bus below, out of sight and out of the way of ballast.
- Test with a multimeter before moving on. Check continuity from the feeder wire to the railhead a few inches away in both directions before covering the joint with ballast or moving to the next feeder.
Choosing an iron and flux for rail work
A temperature-controlled soldering station such as the YIHUA 926 III 60W Digital Soldering Iron Station Kit with Helping Hands makes feeder work noticeably faster and more consistent than a fixed-wattage iron, because rail work benefits from a hotter tip than delicate electronics soldering, hot enough that the joint forms in a second or two rather than several, which is exactly the margin that keeps heat away from nearby plastic ties. A small amount of paste or liquid flux on the cleaned rail web before tinning helps the solder flow and wet the metal properly, which matters more on nickel silver rail than it does on plain copper wire, since nickel silver resists solder more than copper does without help. Wipe the tip clean on a damp sponge between joints rather than letting old, oxidized solder build up on it, since a dirty tip transfers heat poorly and encourages exactly the kind of prolonged contact that damages ties.
Connecting feeders to the bus
Once a feeder reaches the bus below the benchwork, it needs a clean connection to the heavier bus wire that runs the length of the layout. Solder is one option; a screw-down terminal strip such as Terminal Block 8 Circuits 600V 15A Dual Row Screw Terminal Strip 6 Sets is a faster, fully reversible alternative that many builders prefer for feeder connections specifically, saving soldering for the rail joints themselves. How to wire a DCC layout covers bus sizing and routing in full, including how bus length and current together decide the wire gauge the bus itself needs.
Frequently asked questions
Do I really need a feeder for every piece of flex track?
A feeder every three feet is the practical minimum for reliable running on a typical layout, and feeding every individual piece of flex track is more reliable still, though it costs more wire and time. Relying on rail joiners alone instead of feeders is the version that reliably develops dead sections within a year or two as joiners loosen.
Why is my track powered fine now but developing dead spots months later?
This is the classic symptom of a layout wired through rail joiners without feeders. Joiners loosen gradually with seasonal wood movement and slight track expansion, raising resistance at that joint until a locomotive stalls or lights flicker there specifically. Soldering a feeder directly to the rail at that spot, and ideally at similar unfed spots nearby, fixes it permanently.
What gauge wire should I use for feeders?
22 AWG is a common and perfectly adequate gauge for feeder wire on typical HO and N layouts, since feeders are short runs from the rail down to a nearby bus rather than long carriers of current themselves. The heavier bus wire that feeders connect to is sized separately with the bus wire gauge calculator, based on total run length and current.
How do I avoid melting the ties when soldering a feeder?
Tin both the rail web and the wire end separately first, then join them with a brief touch of the iron rather than holding heat on the joint while it slowly flows. Working on already-tinned surfaces cuts the contact time dramatically, which is what actually protects the plastic ties from heat damage, not a cooler iron temperature.
Can I use a terminal strip instead of soldering feeders to the bus?
Yes, a screw-down terminal strip such as Terminal Block 8 Circuits 600V 15A Dual Row Screw Terminal Strip 6 Sets is a reliable, fully reversible way to join feeder wires to a bus, and many builders prefer it for that connection specifically while still soldering the feeder itself directly to the rail, where a mechanical connection is not an option. Reversible terminal connections also make it far easier to trace and fix a specific feeder later if a section ever does develop a problem.
Where on the rail should a feeder be soldered?
To the outside web of the rail, below the railhead, never to the top running surface where a wheel needs a smooth, unobstructed path. Soldering to the web keeps the joint out of sight once ballast is added and keeps the top of the rail perfectly clean for wheel contact.
What soldering iron temperature works best for rail feeders?
A hotter setting than delicate electronics work generally produces a faster, more reliable joint on rail, since the goal is a joint that flows in a second or two rather than several. A temperature-controlled station such as the YIHUA 926 III 60W Digital Soldering Iron Station Kit with Helping Hands makes that setting repeatable, and a clean, tinned tip matters as much as the exact temperature number for a fast, low-heat joint.
Does flux actually matter for soldering rail feeders?
Yes, more than it does for plain copper wire. Nickel silver rail, the standard rail material in the hobby, resists solder more than copper does, and a small amount of flux on the cleaned rail web before tinning helps the solder wet and bond to the metal properly. Skipping flux on nickel silver often produces a dull, weak joint even when the technique and temperature are otherwise correct.
Researched, not professional advice. This page is compiled from published manufacturer specifications, instruction manuals, published NMRA standards and recommended practices, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are hobby convention rather than a standard, and they are labelled that way wherever they appear. Always check a radius, a clearance or a grade against your own equipment before you cut wood or lay rail, because manufacturers vary and so does what your specific models will tolerate. Any permanent mains wiring in a layout room is work for a licensed electrician to your local code.