Which NFPA 70E boundary is designated as the closest approach to energized parts that still requires de-energization before work at voltages 50 V and above?

• A. Limited Approach
• B. Restricted Approach
• C. Proximity
• D. Alarm Boundary

Answer: (A)

The idea being tested is how NFPA 70E defines boundaries around exposed energized parts and when de-energizing is required. The boundary that represents the closest approach to energized parts where de-energizing before work is still required for voltages 50 V and above is the Limited Approach Boundary. This boundary marks the outer limit inside which the risk of shock is present enough that the electrical safe work condition should be established and the equipment de-energized if possible before any work is performed. In other words, you should not enter this zone and start work on live parts unless you can ensure the circuit is de-energized or you have an approved safe-work procedure and protective measures in place. Closer boundaries exist (the Restricted and Prohibited Approach Boundaries) and they impose even stricter controls, but the Limited Approach Boundary is the one that specifically defines the point at which de-energization becomes the required default before work for voltages of 50 V or more.