You can have a short circuit in a decoder but there is no guarantee it will trip a DCC circuit breaker or shutdown a booster.
Myth: DCC circuit breakers protect decoders.
Fact: DCC circuit breaker protect boosters.
The goal of the DCC circuit break is to protect THE BOOSTER by isolating the short locally within the breakers power district so the booster can remain powering the OTHER power districts to keep the other parts of the layout running.
For the DCC circuit breaker to act, a short circuit has to meet specific criteria.
a) The short circuit current must be above the trip point of the DCC circuit breaker.
b) The short circuit current must last for a period of time.
There is nothing in the design of a given decoder that is designed to comply with these requirements when they fail.
FYI: The LED is essentially a “status” light. LED on means the breaker is NOT tripped. LED off means it is tripped and waiting for manual reset. LED blinking means it is tripped and automatically trying to reset.
The SB5 has built in over current sensing (500 milliseconds) for basic self-protection that will continuously try to reset every two seconds until destroyed if left uncorrected. It does not have a breaker that will trip or fuses that will blow.
The EB1 Circuit breaker provides automatic or manual short circuit protection (16 milliseconds or longer) for one power district. Can be used with most DCC systems. Threshold, Duration, type of reset can all be configured.
Features of the EB1: Provides short circuit protection for one power district. Trip current adjustable for 2.5 to 8 Amps. Easy hookup using screw terminals, no soldering. Status indication LED. Additional output for remote LED. Optional manual reset. Adjustable short circuit response time. Adjustable power-up response time to accommodate sound decoder equipped locomotives
Don't forget to use a REAL surge protector not a power strip. Example: http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=NET
The NCE part number for the EB1 is 5240225
To buy a new version of the EB1 direct from NCE click here