Mike Dolt Enterprises
Mike Dolt Enterprises
User: brother, Location: "I have learned, in whatsoever STATE I am, therewi
Asked on: Saturday, March 26, 2011 at 8:25 am EDT
Answered on: Tuesday, May 14, 2024 at 3:19 am EDT
Question: I ran into a situation where a guy was told to 'disconnect' the 'disconnect' switch to a sign outside. The sign had the 'external' switch located on top of it.I told him this was not right because it's a code requirement NEC 2008 600.6(2). Apparently I thought it had the same writing as for motors but apparently not. With motors it would have to be 'impracticable or introduces additonal or increased hazards to persons or property, or in Industrial situations etc..." for the disco to be 'out of line of sight'.The sign disconnect location will allow disco to be 'out of line of sight' so long as it has the 'permanant means of adding a lock'. It doesn't have the 'increased hazards or impracticable' language in it.That seems odd to me and it seems to be a waste of ink because they just circumvented the extra safety they tried to give for having the 'disco' close to the switch if they didnt add the extra 'impracticalbe' language in that section.Does anyone have any insight as to why it does not?Thanks
Reason for Difference in Language
The reason for the difference in language between NEC 600.6(2) (for motors) and NEC 600.6(3) (for signs) stems from the different nature of the equipment and the risks associated with each. Motors
Motors can generate heat and sparks during operation, creating potential hazards for personnel and property. Therefore, the requirement for "within sight" disconnect switches is intended to provide quick and easy access to disconnect the power in case of an emergency.
Signs
Signs do not typically pose the same potential hazards as motors. They do not generate heat or sparks, and the risk of electrical shock is minimal. Therefore, the requirement for "permanent means for adding a lock" is considered sufficient to ensure safety.
Purpose of Permanent Lockout
The permanent means for adding a lock in NEC 600.6(3) allows for the disconnect switch to be located out of sight, provided that it can be locked in the open position. This feature is designed to prevent accidental or unauthorized re-energization of the sign, which could create a hazard if the sign is being worked on or repaired.
Rationale for Out-of-Sight Disconnect
In some cases, it may be necessary to locate the disconnect switch out of sight due to practical considerations. For example, if the sign is located high above the ground, it may be impractical to place the disconnect switch within sight. In such cases, the permanent means for adding a lock allows for safe operation while also maintaining the ability to disconnect the power in an emergency.
Conclusion
The difference in language between NEC 600.6(2) and NEC 600.6(3) reflects the different risks associated with motors and signs. While motors require "within sight" disconnect switches for increased safety, signs can have out-of-sight disconnect switches as long as they are equipped with a permanent means for adding a lock. This approach balances safety and practicality, allowing for the installation of signs in various locations while still providing a reliable means of disconnect. Flag for review