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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:
| “Silver” rail |
1.45 milliohms per inch |
| Brass rail |
0.48 milliohms per inch |
| #16 copper wire |
0.33 milliohms per inch |
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
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