Tuesday, December 09, 2014

Correct Installation of Emergency Pull-Cords

Emergency pull cords are a form of an emergency stop control and are usually installed on conveyors or long machine lines where there are multiple work areas for an operator. They are a great alternative to installing multiple emergency stop buttons, but in order to be effective they need to meet CSA design requirements stated in CSA Z432-04 Section 7.17.3.

Usually the cords we have seen around meet the first requirement, which is that they are clearly visible and readily accessible. The majority also have a three-position switch, which means an emergency stop signal would be initiated if the cord is pulled and also if the cord were to break.

The most common issue that we have seen with pull cords is the anchoring of the cord. Usually one end is anchored to the switch and the other end is anchored to a bolt or hook. This set up creates a violation because if the cord was to be pulled directly parallel to the anchor point, there would be no movement and therefore the switch would not activate. A proper pull cord installation will have one end anchored to the switch and the other end anchored with a spring or another switch, as shown in the diagram below.

emergency pull cord

 

And as always, don’t forget to wire your emergency pull cord through a control reliable safety relay. If you have any questions about the state of your pull cords, don’t hesitate to give us a call.

 

 

 

Posted by Kristin Petaski at 10:38 PM 0 Comments