The highest voltage rating for circuit breakers used on DC systems that UL recognizes (in the classic exam-style question you’re referencing) is 600 V DC.

Quick Scoop Answer

  • For the standard multiple‑choice question, the correct choice is 600 V as the highest UL‑recognized voltage rating for DC circuit breakers.
  • Modern UL guidance for specialized DC breakers (like PV and battery systems) allows marked ratings up to 1500 V DC , but that is a newer, application‑specific context and not what the quiz question is aiming at.

So if you are answering a test or forum quiz that asks:
“What is the highest voltage rating for circuit breakers used on DC systems that UL recognizes?”
the expected answer is: 600 V DC.

Small Technical Nuance

  • Traditional molded‑case and panelboard breakers in many code and training materials top out at 600 V DC as the recognized maximum rating.
  • UL’s more recent marking guide for molded case circuit breakers used in PV and battery power supply systems permits DC voltage ratings up to 1500 V DC maximum , specifically labeled for those systems.

Forum / “Latest News” Flavor

  • In recent years (especially with solar and large battery systems becoming common), there has been more discussion in forums and trade publications about high‑voltage DC breakers up to 1000–1500 V DC and how UL recognizes and marks them.
  • However, training questions and many legacy references still use 600 V DC as the canonical “highest UL‑recognized voltage rating” for general DC circuit breakers, which is why that remains the go‑to test answer.

TL;DR:
For the question as usually written in textbooks and practice exams, the answer is 600 V DC.

Information gathered from public forums or data available on the internet and portrayed here.