Trapped Key Interlocking

Mechanical locking portion of a trapped key interlock secured to the door of an electrical switchgear cabinet with one-way tamper-resistant screws.

Many machine designers think interlocks are exclusively electrical devices; a movable mechanical guard is fitted with an electrical interlocking device, and the interlocking device is connected to the control system. Trapped Key Interlocking is an equally effective way to interlock guards that is often more appropriate in severe environmental conditions or where the guard is…

Read More

Five reasons you should attend our Free Safety Talks

Banner for the Free Safety Talks

Reason #1 – Free Safety Talks You can’t argue with Free Stuff! Last week we partnered with Schmersal Canada and Franklin Empire to put on three days of Free Safety Talks. We had full houses in all three locations, Windsor, London and Cambridge, with nearly 60 people participating. We had two great presenters who helped…

Read More

Q & A: Can Safety PLCs be used for Lockout?

Disconnect Switch with Lock and Tag

Questions about equipment lockout using safety PLCs are more frequent these days. Can Safety PLCs be used for lockout? Safety professionals don’t always agree on this controversial topic!

Read More

Updates to Popular Articles

We’ve recently updated a couple of our popular articles! Check them out! Busting Emergency Stop Myths Reader Question: Multiple E-Stops and Resets

Understanding the Hierarchy of Controls

The Hierarchy of Controls illustrated as an inverted triangle with each level of the hierarchy written one above the other, starting with Inherently Sfe design, then Engineering Controls, then Information for Use, then Administrative Controls and finally descending to PPE at the bottom. An arrow with the text "Effectiveness" on it runs parallel to the triangle and points downward from Inherently safe design to PPE.

(Eds. note: This article was originally written in 2011 and was updated in Nov. 2018.) The “Hierarchy of Controls” is one approach to risk reduction that has become entrenched in the Occupational Health and Safety (OHS) sector. There are other approaches to risk reduction which are equally effective but are less rigidly structured. If you…

Read More