Can I use a "conventional" limit switch for safety applications?

Yes, it is possible to use a "conventional" limit switch for safety applications, as long as the switch is "positive action"

Definition of positive action:

• A limit switch is said to be positive action if its normally closed (NC) contacts can be changed to the open position with certainty
  
• The symbol indicating this type of operation is an arrow in a circle.

Contact with Positive Opening

Notes:

Other conditions may be necessary for integrating a limit switch in a safety application:

• Redundancy of contacts of NC contacts
• Integrity of the sensor, the contacts in the sensor must not be modified.
• For these reasons Schneider has developed a range of safety limit switches, that can be recognised by their red colour.
• They have a plate that prevents access to the screws. This plate is attached using "5 lobe torque" safety screws, and the fixing tool is supplied with the product.

The standard IEC XC range of standard Limit Swithces and the NEMA SquareD Limit Switches 9007 have contact blocks that contain Positive Opening contacts, please check for the documention or the product for the Positive Opening symbol.

Schneider Electric India

The standard IEC XC range of standard Limit Swithces and the NEMA SquareD Limit Switches 9007 have contact blocks that contain Positive Opening contacts, please check for the documention or the product for the Positive Opening symbol.