Setting a Safety Zone

OSHA and NFPA 70E set Safety standards and requirements for working, approaching and being around energized Electrical Power Sources.  And these boundaries and zones are based on the NFPA 70E: Table 130.2(c) “Approach Boundaries to Live Parts for Shock Protection.”  This table is based on the “nominal” voltage range of the equipment being serviced.

Polytron’s policy standard is to not service equipment over 600V, but there are always the possibilities of other circumstances being involved.  So there is no absolute rule to where the boundaries are placed, and the distances that will be applied to them, it is all based on the nominal voltage you are servicing.  Using Polytron’s policy standard of working on 600V or less, let’s see where our boundaries would be placed.

Limited Approach Boundary

10 feet - 0 inches (exposed movable conductor), 3 feet - 6 inches (exposed fixed part)

• Qualified (trained) persons are allowed to cross boundary
• Unqualified (not trained) persons can only cross if escorted by qualified person
• Exposed to greater risk of Shock Hazards
• Proper Personal Protection Equipment (PPE) must be worn when equipment is energized

Restricted Approach Boundary

1 foot -  0 inches (includes Inadvertent Movement Adder)

• Qualified persons are allowed to cross boundary (under these conditions)
  • Have approved plan with hazard/risk analysis completed
  • Use ALL PPE approved for the conditions
  • Have the ability to position his/her body in a way to minimizes risk of inadvertent contact
• Unqualified (non trained) persons are NOT permitted to cross for any reason
• Exposed to increased risk of Shock due to ARC OVER (from equipment to person through the air) combined with inadvertent movement

Prohibited Approach Boundary

0 feet - 1 inch (considered the same as making contact with it)

• Qualified (trained) persons are allowed to cross boundary
• Must have all the PPE approved for the conditions
• Exposed to potentially energized conductors and exposed to Shock, Arc Flash, and Arc Blasts

Flash Protection Boundary

• UNLIKE OTHER BOUNDARIES THIS IS SET AT 4 FEET REGARDLESS OF NOMINAL VOLTAGE

The Flash Protection Boundary has been set by NFPA 70E standards at 4 feet; this has been determined to be the point that persons could receive second degree burns at if an Arc Flash were to occur.

These boundaries should be clearly marked to warn of the existing dangers, and help determine the proper PPE is used to approach inside of these zones.

Polytron engineers conduct machine and panel work applying all of the most current safety requirements and recommendations.  We want to ensure that your facility is safe for your employees during the time we complete our work.