Looking for opinion on using a molded case breaker for a lockout? My question concerns an operator throwing a disconnect with a molded case breaker to shut off the machine to clear a jam. Typically if we are doing any electrical work we check to make sure the power has been removed, but since we are not doing any electrical work do we still need to check to make sure the breaker opened or can the operator try to start the machine and if it does not start they are safe to clear the jam? I'm old school and I would want the power checked before I stuck my hands in? How do other folks accomplish this? Looking forward the replies!
LOTO molded case breaker
- Thread starter cornbread
- Start date
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Regardless of code/regulations, I'd want it locked off with the key in my pocket before I stuck my hands in there.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Ask yourself what the danger might be, if someone were to reclose the disconnect while a person is trying to clear the jam. In a purely electrical environment, if you have your hands inside an electrical component and someone recloses the power supply breaker, the danger is that you might get a shock (or worse). An LOTO is certainly necessary for that situation.
But it sounds like you are describing a different situation. I might want to know whether any motor would automatically restart and possible trap the worker's hands or clothing on a rotating piece of machinery, if someone were to reclose the disconnect. I might also want to know what it would take to "clear the jam." I have cleared paper jams from large office copiers without turning them off or unplugging them. In that situation I don't believe there is any danger that the copier would start operating until the jam is cleared and the reset button is pushed. But if clearing the jam requires tools and time and disassembly of machine components, it becomes a different situation.
The bottom line is still that safety outranks production. I don't know what OSHA rules would have to say, but I think at a minimum the person reaching in to clear the jam should put their own lock on the disconnect and hang on to its only key. I agree with Besoeker on this point. A tag-out might or might not be a necessary additional step, depending on the nature of the task.
But it sounds like you are describing a different situation. I might want to know whether any motor would automatically restart and possible trap the worker's hands or clothing on a rotating piece of machinery, if someone were to reclose the disconnect. I might also want to know what it would take to "clear the jam." I have cleared paper jams from large office copiers without turning them off or unplugging them. In that situation I don't believe there is any danger that the copier would start operating until the jam is cleared and the reset button is pushed. But if clearing the jam requires tools and time and disassembly of machine components, it becomes a different situation.
The bottom line is still that safety outranks production. I don't know what OSHA rules would have to say, but I think at a minimum the person reaching in to clear the jam should put their own lock on the disconnect and hang on to its only key. I agree with Besoeker on this point. A tag-out might or might not be a necessary additional step, depending on the nature of the task.
Found this searching this forum
http://forums.mikeholt.com/showthread.php?t=105691
NFPA 70E Lockout Requirements
Our plant currently uses none-electrical personnel for many lockouts that do not require electrical work. Example would be a pump change. Here is a very basic procedure for a single point lockout:
-Shutdown equipment
-Open Disconnect at MCC and apply lock to disconnect
-Attempt to start equipment
-Perform work.
Does NFPA 70E require a qualified person to verify absence or voltage for this type of lockout?
Thanks
Seem from this the thread the answer is yes... verification of absence of voltage.
http://forums.mikeholt.com/showthread.php?t=105691
NFPA 70E Lockout Requirements
Our plant currently uses none-electrical personnel for many lockouts that do not require electrical work. Example would be a pump change. Here is a very basic procedure for a single point lockout:
-Shutdown equipment
-Open Disconnect at MCC and apply lock to disconnect
-Attempt to start equipment
-Perform work.
Does NFPA 70E require a qualified person to verify absence or voltage for this type of lockout?
Thanks
Seem from this the thread the answer is yes... verification of absence of voltage.
just the cowboy
Inactive, Email Never Verified
- Location
- newburgh,ny
We did it that way
We did it that way
When I work for a large plant, when clearing a jam we did the following.
Stop machine.
Pull disconnect and listen for the clunk noise of it opening. ( yes it can still make noise and fail. )
If jam was in arms reach AND line of sight of disconnect, a lock was not needed, if out of reach OR sight you HAD to lock it out.
Check to see if machine will start with disconnect off, to check if blades opened ( Yes one leg may stay in).
Clear jam, turn on disconnect, restart machine.
That was for jam clearing ONLY, if maintenance had to work on it, it had to be locked out and verified power is off.
We did it that way
When I work for a large plant, when clearing a jam we did the following.
Stop machine.
Pull disconnect and listen for the clunk noise of it opening. ( yes it can still make noise and fail. )
If jam was in arms reach AND line of sight of disconnect, a lock was not needed, if out of reach OR sight you HAD to lock it out.
Check to see if machine will start with disconnect off, to check if blades opened ( Yes one leg may stay in).
Clear jam, turn on disconnect, restart machine.
That was for jam clearing ONLY, if maintenance had to work on it, it had to be locked out and verified power is off.
Timbert
Member
- Location
- Makawao, Hawaii
OSHA says for lockout/tagout the minimum requirements are to lock out the energy isolating device (MCCB in this case) and then verify isolation by attempting to operate via the controls.
As always with anything safety related, you should do a hazard analysis.
In our analysis, having personnel open a panel and expose themselves to arc-flash and electrical hazards was MORE of risk than the MCCB failing in such a manner that the machine would not operate when tested but could be operated by some other means or circumstances.
Zero voltage verification is only done when doing work that would expose personnel to electrical hazards.
As always with anything safety related, you should do a hazard analysis.
In our analysis, having personnel open a panel and expose themselves to arc-flash and electrical hazards was MORE of risk than the MCCB failing in such a manner that the machine would not operate when tested but could be operated by some other means or circumstances.
Zero voltage verification is only done when doing work that would expose personnel to electrical hazards.
Looks like OSHA 1910.147(d)(6)
Verification of isolation. Prior to starting work on machines or equipment that have been locked out or tagged out, the authorized employee shall verify that isolation and deenergization of the machine or equipment have been accomplished.
I guess trying to start the machine would be one way of verification. That's going to be a big shift in our thinking as we typically assume the machine needs to be placed in a electrically safe condition as defined by NFPA70E. It will be interesting to see how our safety folks handle this.
Verification of isolation. Prior to starting work on machines or equipment that have been locked out or tagged out, the authorized employee shall verify that isolation and deenergization of the machine or equipment have been accomplished.
I guess trying to start the machine would be one way of verification. That's going to be a big shift in our thinking as we typically assume the machine needs to be placed in a electrically safe condition as defined by NFPA70E. It will be interesting to see how our safety folks handle this.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
As has been mentioned, verifying absence of voltage is important to electrical maintenance tasks, but "unplugging" a jammed machine isn't an electrical task. Is possible to clear this machine workers may need to turn off/lock out other energy sources such as steam, air, gas, etc.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I think sometimes the need to verify absence of voltage is not well understood.
It is generally only needed when an employee would be exposed to energized parts.
If it is just about motion, it would not matter any if one blade of a switch failed. There still would be no motion. However, there could be live electricity there just waiting to get someone that exposed themselves to it.
It is generally only needed when an employee would be exposed to energized parts.
If it is just about motion, it would not matter any if one blade of a switch failed. There still would be no motion. However, there could be live electricity there just waiting to get someone that exposed themselves to it.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Some kind of shaft lock instead of an electrical disconnect might be acceptable locking means for mechanical lockout on a motor driven machine.
Might be poor design from the motor's perspective, but still protects the employee accessing the moving parts from accidental startup.
Might be poor design from the motor's perspective, but still protects the employee accessing the moving parts from accidental startup.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
One thing worth adding here is that for us in the electrical trades, LO/TO is almost always just electrical. NFPA 70E is about electrical hazards. But LO/TO is an OSHA requirement and they refer to all forms of energy being removed. So if you have air, water, hydraulics or even flywheel energy, LO/TO of those sources is still required. The point being that what you asked, regarding needing LO/TO even if not doing electrical work, is exactly what LO/TO is all about, not just electrical. So the answer is yes, you need to do it.
Perhaps that's how many think of it. Please don't think I'm contradicting you. It is a risk if you are working on the electrical aparatus.
My background as you probably know, is mainly industrial. I suppose the paper industry is as good an example as any. A paper (making) machine* has many moving parts which need regular maintenance. This requires the maintenance crew to get into the guts if the machinery to remove and replace parts.
There is no way this would be allowed to happen without LOTO and a written permit to work. The risk is not electrical - it is physical. And that's what the OP seems to be looking at.
*Big beast.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
That was actually my point, it's NOT just an electrical issue, it's a general safety requirement when working on machinery.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Context...
No argument .. a LOTO is needed, my question goes back on how to implement them. Our current standard states we put the machine in an electrically safe condition... going back to NFPA70E we will verify that by using a meter (electrician). This has worked for us for the past 40 years, but we are a continuous process so we typically don't deal with daily jams. We are now starting to install packaging equipment and this is where the questions are being asked, how to properly lock out the machine to allow operations to set up / service and repair the machine (with out calling an electrician). The debate is .. does our standard need to be revised to have two type of lock outs... electrical and operational? If we do an operational lock out ... what constitutes a verification the hazard has been removed? ... testing the start button? My reservation with that is the numerous interlocks that could be keeping a machine from starting that has nothing to do with a proper lockout.
Our safety dept. will be doing a risk assessment and I hope to use some of the information from this thread in that discussion.
Appreciate everyone replies.
Our safety dept. will be doing a risk assessment and I hope to use some of the information from this thread in that discussion.
Appreciate everyone replies.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Some machines pressing start button and nothing happens is enough, others that may be interlocked with other things or even have self contained limits that lock things out may need additional evaluation on how to determine when it is in a safe condition, this means exact procedure can vary some from one machine to another.
cdevine
Member
- Location
- Brisbane, Australia
Two verification procedures for the same equipment is quite common. One procedure for electrical work and one procedure for mechanical work. There is less confusion when you can use the one procedure for mechanical verification across all machines. The problem is with Try Start, as has already been indicated, it is often not conclusive and therefore not possible to use on all machines or in all circumstances. That is why some sites have reverted to voltage tests on the load side of disconnects, even for mechanical verification, as it works in most cases however it is time consuming and expensive. I suspect that is why there is confusion in industry that voltage tests are a requirement for all verification when I don't think that the evidence is there.
This gives rise to the question - How can any worker perform a voltage test on the load side of a disconnect quickly, accurately and safely? This question has motivated many to develop LED voltage indicators. They are inherently quick and safe to use but unless recognized safety methods are employed, accuracy may be compromised. Safety methods require more than just dual LED indications or a reliance on the operator to initiate the voltage indication or claiming a SIL level. But that is another story altogether!
This gives rise to the question - How can any worker perform a voltage test on the load side of a disconnect quickly, accurately and safely? This question has motivated many to develop LED voltage indicators. They are inherently quick and safe to use but unless recognized safety methods are employed, accuracy may be compromised. Safety methods require more than just dual LED indications or a reliance on the operator to initiate the voltage indication or claiming a SIL level. But that is another story altogether!
meternerd
Senior Member
- Location
- Athol, ID
- Occupation
- retired water & electric utility electrician, meter/relay tech
One personal experience at a pumping station. I was there doing unrelated wiring. The water techs are allowed to de-energize pumps by locking off the molded case breaker and tagging it. A lock isn't required if they are within sight of the breaker. But...an accident happened (injury was minor, thank God). The operator manually opened a solenoid operated hydraulic discharge valve, which allowed water to backflow from the tank uphill and cause the pump to rotate backwards at a pretty fast clip. The tech had gloves on and was undoing coupling bolts and got his hand jammed in the housing. So...the mechanical energy may still be there even when pushing a start control verifies no power. It's all about training.
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