FORT WORTH, Texas -- After the lights went out on the third turn of Friday's O'Reilly Auto Parts 300, Texas Motor Speedway officials decided to replace all of the circuit breakers for the Samsung Mobile 500, according to NASCAR.com.
An outage caused two cautions during the O'Reilly 300, including a 10-minute red flag to replace the broken breaker. Maintenance crews replaced the rest of the breakers overnight.
The breakers could have overheated, causing them to shut off to avoid further problems.
The circuit breakers were 15 years old, according to the report.
This is the second year that the O'Reilly 300 and Samsung Mobile 500 races took place at night.