The Circuit Breaker No. 91 was available beginning in 1957 and could be purchased until 1960. This circuit breaker should not be confused with the Pre-war version that went by the same number. This Post War version was adjustable from 1 to 6 amps and was worked by an electromagnet. Packaged in a LIGHT TAN case with an illuminated RED reset button, this accessory would insure transformer protection when hooked in line with the track current.

Dimensions: 4-3/4" long, 1-3/8" wide.

While a need for this accessory is unquestioned, there still remains the question as to why Lionel would introduce this breaker in 1957 and not produce it after 1960. I have a theory why this happened, so bear with me. Underwriters Laboratories sometime in 1956 required circuit breakers to be installed on all transformers of 30 watts or more. Lionel must have reached some kind of agreement with them (by including this circuit breaker in trains sets?) and this was an effective compromise until they could install a circuit breaker in their small transformers.

Here’s a list of the small transformers that Lionel offered between 1953 and 1960 that did not have breakers:

No. 1015 1956-60 45 watts
No. 1016 1959-60 35 watts
No. 1043 1953-57 50 watts

After 1960 the following transformers came equipped with circuit breakers:

No. 1010 1961-66 35 watts
No. 1025 1961-69 45 watts
No. 1073 1960-66 60 watts

The only flaw I can find with this "guess" is that the No. 1026 produced from 1961-64 that didn’t have a circuit breaker...but then it would only produce 25 watts.

This theory is further substantiated by the production these larger transformers:

No. 1053 1956-60 60 watts, whistle control, no breaker
No. 1063 1960-64 75 watts, whistle control, with circuit breaker

There seems to be a change over time for these transformers that is centered around the year 1960.

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