There are many synonyms for the phrase "normal danger system", which refers to the standard safety measures put in place to prevent harm or accidents. Some alternative phrases could include "standard safety precautions", "basic risk management system", or "commonplace hazard prevention measures". Other options might be "routine danger mitigation protocols", "typical safeguards against harm", or "ordinary safety measures". Ultimately, the choice of synonym will depend on the context and purpose for which the phrase is being used. Whether emphasizing the routine or common nature of safety measures, each synonym conveys the importance of taking proactive steps to ensure safety and prevent danger.