vibrating circuit breaker

Al,

Been thinking about the response to this for a while. It would be nice for the other engineers to step forward with their thoughts on this as well.

Before I answer, let me explain I am an electrical engineer, master electrician, and an ASE master. I have worked as an expert witness on electrical cases involving electrical fires, lightning, and voltage surges. Electricity is nothing to play with, and it is always a good idea to take every precaution to ensure the system is as safe as possible.

Having said that, your question relates to the replacement of the circuit breaker(s) in your Pierce. Before I would think about the breaker, I would first determine the condition of the items the breaker is designed to protect, namely the wiring and devices being fed the electricity. Circuit breakers in the early ’30’s were rare. Most auto manufacturers used fuses, as they were cheaper. Even into modern times, autos are usually protected by fuses. Circuit breakers, then and now, were used to protect devices, such as headlights, that were essential to the car’s operation, and where the complete loss of the circuit could have disastrous results. Breakers in cars were designed to trip in an overcurrent condition, and reset after some period of time. This was often done using a bimetal strip, which curved in an overcurrent conditon, and reset after the metal strip cooled. It is the same design in a flasher.

Assuming the circuit breaker is for an essential circuit, I would first check the wiring and the device for wear and safety. If it is still good (and I have found in houses, for instance, that older “BX” wiring can hold up to surges better than the newer “Romex” wiring), then you may want to leave well enough alone for a show car or one in the HPOF class. Be sure to check the breaker to ensure it is working properly. I have seen instances where a breaker was used and a fuse was installed in series with it. The fuse was usually rated significantly higher, say 3 to 6 times the breaker rating, and was used to prevent shorts in the event of a failed breaker. The best situation would be to replace the wiring and breaker with correct reproduction wiring from a harness manufacturer.

If the car is a driver, I would replace the wiring with new wiring of the same or lower gage (wire with a smaller number is a larger wire that can handle more current) and a temperature rating as high as possible (90 to 105 degrees C). Make sure to replace it in the fabric sleeves Pierce used (available at Restoration Supply and other places), and check to see the wiring is not susceptible to wear or heat. I always try to solder connections instead of using crimps wherever possible.

Hope this helps!

Bob

I like the idea of a higher capacity fuse inline with the original circuit breaker, a very good idea to back up the older circuit breaker with a simple fuse. Just make sure the fuse is rated for more current than the CB.

Greg Long