LOTO vs Alternative means and Interlocked guards
Are level 4 interlocked doors a sufficient means for LOTO when it relates to machine maintenance and servicing? I am being told by my boss that interlocked guards are a sufficient alternative means for maintenance tasks that are not routine, repetitive, and integral.
However, all of the interpretation letters i can find from OSHA/TOSHA state "Some acceptable alternative measures include specially designed tools, remote devices, interlocked barrier guards, local disconnects, or control switches which are under the exclusive control of the employee performing the minor servicing."
They specifically call out minor serving but DO NOT call out zero-energy state for maintenance.
If interlocked guard doors are sufficient, where can I find this information? And if they are not, does OSHA specifically call out the definition of maintenance tasks that would fall under MSE.
Comments (11)
If it does not meet the minor servicing exception (things that are routine, repetitive, and integral to the operation), then interlock guards are NOT an acceptable form of LOTO. Interlocks do not isolate the energy - it's basically the same as hitting an e-stop button. Alternative methods of protection (e.g., interlocks, control switches, etc.) are ONLY acceptable when using the minor servicing exception.
ANSI has a lot of alternative methods in their LOTO standard (ANSI Z244.1-2016), but many of them are NOT compliant with OSHA's LOTO standard. It's known that the ANSI committee didn’t try to align fully with every OSHA requirement found in 1910.147.
LOTO vs Machine Guarding, the way I explain it in training…
A machine guard (interlock device) is meant to protect the operator and workers from injury by moving parts.
LOTO, “covers the servicing and maintenance of machines and equipment in which the unexpected energization or start-up of the machines or equipment, or release of stored energy could cause injury to employees”.
Drew has it correct, LOTO is about energy control, not stopping the machine, as in the case of an interlock device.
I think Bob and Drew have it right! I have been fighting the old battle over 1910,147(a)(2) and especially the "Note" for most of my over 50 years in this business! I started in "operations" or "manufacturing" (supervisor - manager) arguing over a "liberal" interpretation of production operations. A few years later as Personnel/Safety manager over a strict interpretation of production operations. So I have argued it all ways imaginable. I think that is very ironic.
To me it finally comes down to PROTECTING the EMPLOYEE!!! But you have to be practical too.
1910.147 clearly says that Normal Production Operations are not covered when Subpart O is applied (machine guarding). What about service or maintenance? I always teach LOTO and Subpart O together! With machines you cannot have one without the other! OSHA says you must protect employees from hazards! On machines that means Guarding or LO (I do not like to use TO because in my Lockout programs Tags are ONLY used for Lockout ID or to enhance locks! But we can get in to that at another time!).
So in service and maintenance are interlocks sufficient protection? Drew and Bob are right, per OSHA NO. But in the real world this is what I do. I look at the risk! Let me give an example. On large CNC Tuning Center.
One hopeful thing on the horizon is that the LOTO standard may be updated (within our lifetimes?). A notice of proposed rulemaking (NRPM) is overdue and there are hints that the ANSI approach may get at least partially incorporated. Specifically updating to accept safety-rated interlock systems. Technology has improved a lot in the 34 years since the standard was introduced.