Track Resistance

There seems to be a few myths concerning nickel-silver track for HO train layouts. The myths are:

1.) The track is silver, or contains silver. Nickel-silver track contains no silver, it is only silver colored.

2.) Nickel-silver track tarnishes slower. My layout is 50% nickel-silver and 50% brass on each of two main lines. Each mainline gets the same traffic over its length. I've found, over time, there is no significant or noticeable difference in the rate at which the track needs cleaned, but rail with plastic wheels on cars does appear to make bad wheel to rail connections more frequently.

 3.) Nickel-silver rail is more conductive. This is absolutely false.

I measured rails by feeding lengths of sample rails from a 10-volt power supply through a ten ohm resistor. The exact power supply voltage was adjusted to 1-ampere rail current. I measured voltage drop across five inch lengths of rail, using proper measurement techniques, with a precision millivolt meter. The following results are for code 100 rail samples:

Conclusions Rail Resistance

This data, the average of several different rail types, indicates "silver" rail has about three times more resistance per foot than brass rail.

Brass code 100 and #16 wire are somewhat close in inch per inch resistance. This means if we have ten feet of copper (with perfect connections) attempting to jumper seven feet of brass code 100, the wire resistance and rail resistance are approximately equal. Not considering joints, the best we hope for is a 50% reduction in resistance.

If we have ten feet of copper wire bridging 2-1/2 feet of silver rail, the copper has slightly lower resistance.

Joint or Rail Joiner Resistance

A common debate is whether to solder rail joiners, or how much resistance rail joints add to the system. I measured joint resistance on a few dozen unsoldered joints.
 

• Joint resistance of looser fit joints was 48 milliohms average. That's like 3 feet of silver rail and 8 feet of brass rail.

• Joint resistance of tight fresh joints was 6.5 milliohms average, about the same as 4.5 inches of silver rail and 13.5 inches of brass rail.

• Soldered joints were all below 0.5 milliohms, too low to get a good reading. Soldered joints can be considered negligible resistance.

Link to turnout resistance troubles

Link to proper track joint soldering