Spike Protection

Modern O-Gauge 3 rail and 2 rail S-Gauge Trains that operate on AC voltage (especially those with TMCC, Legacy, DCS, or other command/control boards) use delicate surface-mount components that can be damaged by voltage spikes. These spikes often occur when:

• A train derails or causes a short on the track
• You use older postwar transformers (ZW, KW, LW, 1033, etc.)
• The transformer’s internal breaker reacts slowly to a fault

The easiest way to protect against voltage spikes is to add TVS diodes (Transient Voltage Suppressor) to the output of your transformers.

In the Lionel hobby community (O Gauge Forum, ModelTrainForum, etc.), the 1.5KE36CA is one of the most frequently suggested TVS diodes for this exact purpose.

The 1.5KE36CA is bidirectional, which is perfect because Lionel track power is AC (typically 0–18 V RMS, with peaks around ±25 V).

• It stays completely out of the way during normal operation (up to ~30.8 V).
• When a spike exceeds its breakdown voltage (~34–38 V), it clamps the voltage almost instantly (in a few nanoseconds) and safely shunts the excess energy.
• It can handle up to 1500 watts of peak pulse power, which is more than enough for the short-duration spikes that damage train electronics.

Best Installation Practices

For maximum protection of your modern trains:

1) At the transformer outputs (most common and effective):

• Install one 1.5KE36CA across each variable output (e.g., between the “A” and “U” terminals on a ZW, or equivalent on other transformers).
• Direction does not matter because it’s bidirectional.

2) Add fast-acting 5 A circuit breakers in series with each output. TVS diodes absorb spikes, but breakers help limit sustained shorts. Many hobbyists use both together.

3) Optional extra protection:

• Place additional 1.5KE36CA diodes at track lock-ons or power districts.
• Some people even install a small TVS inside the locomotive itself (across the power input to the circuit board).
• CAUTION: For MTH DCS spike protection, place the 1.5KE36CA TVS diodes sparingly (1–2 per power district max if running DCS) to avoid signal degradation.