Circuit Protection for Toy Trains - Photo Sequence
All power feeds from toy train transformers must have circuit protection in the line. Use the lowest value protection that will hold the circuit closed. Track for passenger cars will require the highest value protection.
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Protect you, your house, trains, wire, and accessories. Transformer internal breakers protect transformers, NOT trains. Shorts or faults can damage your toys and burn down your house. Circuit protection on the low voltage side of transformers is the same as having breakers in the circuit box for your house wiring. |
Circuit Protection Sequence from 14V
Light Bulbs
to the 120V Electrical Panel
The A terminal powers a major track.
The B terminal powers several small accessory circuits.
The C terminal powers Z-Stuff switch machines. The D
terminal powers a beginner track.
The PTC Resettable Fuses (orange discs) automatically reset when power is shut off and fault is cleared. The PTC fuses are really hot when tripped and can burn your finger. The panel mount breaker switch shows a white strip when tripped and is manually reset when the fault is cleared.
Photos are for illustration purposes.
Click on some photos for a larger illustration.
For links to expanded topics click on underlined topic.
| A 5 - 18 V |
B 14 V |
C 13.5 V |
D 5 - 18 V |
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 Protect lamps and accessories in small groups. Smaller fuses/breakers protect small wires and modern electronics. |
 Switch Machines Wired in Pairs are Operated with One Controller. See Wiring Below |
 Note white phase tape on common wire. |
 The MTH DCS TIU below is Optional. |
 See Scenery as a necessary evil. |
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A beginner track is best protected with a 3A Panel Mount Circuit Breaker . The beginner can see the trip indicator and reset when fault is cleared. |
 Inputs must have fuse/breaker in line from transformer. |
 Protection for 5 Lighting Sections (1.6 A each) |
 1.6 A Switch Machine Protection |
 see Breaker Tripped |
This sample terminal strip shows
wires from transformer, power going through the PTC fuses, power
out to load. The
color code
is black, red, blue, and brown. Phase tape is used
when correct color wire is unavailable.
Yellow arrows point to transformer terminal wires. Orange
arrows point to load terminal wires.
Lionel Postwar ZW Transformer
 Transformer Breaker is Buried Under the Wiring. |
 Ring terminals crimped and soldered to wires are helpful. |
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See Transformer Ratings and Connections
Postwar transformers are derated 80% when in use.
Plug the transformer into switched grounded plug strip and scenery can be shut off when guests are not present. Extension cords should be 16 gauge 3 wire grounded for modern electronics. The Trolley control is plugged into the extension cord so the trolley runs when the town lights are off.
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 One of 8 Plugs on 15A 120V Breaker |
The bottom of Run Room duplex receptacles are controlled by a wall switches.
Basement 120V Electrical with 15 Amp Breaker Noted
Reference Links