key switches
- Thread starter zmikc115
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Re: key switches
All I have to say is Each person working on the equipment should have a lock on it. Now if you have one key for a key switch, which that is questionable to be used as a lockout device, depends on how it breaks the connection. If you maybe put said key in a lock box and a joint locking clasp with all parties locks on it, that may work, but I would still question key switch as viable means for locking out equipment.
Also is that key the only one in existence, or do several people have keys for the switch. One Lock, One Key, per person.
All I have to say is Each person working on the equipment should have a lock on it. Now if you have one key for a key switch, which that is questionable to be used as a lockout device, depends on how it breaks the connection. If you maybe put said key in a lock box and a joint locking clasp with all parties locks on it, that may work, but I would still question key switch as viable means for locking out equipment.
Also is that key the only one in existence, or do several people have keys for the switch. One Lock, One Key, per person.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Re: key switches
I don't know your machine configuration, but "normally" the way this happens is one guy takes the key out, puts it in his pocket and goes and unjams the machine. If it is a large machine or it takes more than one person to unjam it, you have more than one key.
I don't know your machine configuration, but "normally" the way this happens is one guy takes the key out, puts it in his pocket and goes and unjams the machine. If it is a large machine or it takes more than one person to unjam it, you have more than one key.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: key switches
I don?t quite understand the concept here. What does the key do? In other words, what I am trying to understand is this: Where is the key, when people are reaching into the machine to remove the jam?
Does the key stay in a person?s pocket until maintenance is needed, and then you use the key to somehow disable the equipment, and the key remains in the lock until it is time to turn the machine back on? I would hope not, as there would be no way to make this process safe. That is because anyone can see the key in the lock, and turn it back to the ?On? position, without first verifying that the area is clear.
Or does the key stay in the machine, and does the process of removing the key turn the machine off, and so long as the key is in someone?s pocket the machine cannot be used? This might be safe, but only if there is only one key.
Or is it that a person can take the key out of a pocket, use the key to turn off the machine, and then place the key back in the pocket. This might also be safe, but only if there is only one key.
If either of the later two situations, it would be extraordinarily dangerous for there to be more than one key.
The only way to make something like this safe is for the people reaching into the machine to be able to see, in their immediate vicinity, physical evidence that the machine is locked out, and that the machine cannot be unlocked until that ?physical evidence? is no longer in their immediate vicinity. Think of it like the disconnect device that is required to be accessible to, and in full view of, a maintenance person who is working on an outdoor air conditioning unit. That worker will remove the disconnect, and can see the open disconnect for all the time that the work is going on. But if the disconnect were out of sight, and if there were two plugs that could restart the a/c unit, would you trust that no person will use the second plug while your hands are in the unit?
I don?t quite understand the concept here. What does the key do? In other words, what I am trying to understand is this: Where is the key, when people are reaching into the machine to remove the jam?
Does the key stay in a person?s pocket until maintenance is needed, and then you use the key to somehow disable the equipment, and the key remains in the lock until it is time to turn the machine back on? I would hope not, as there would be no way to make this process safe. That is because anyone can see the key in the lock, and turn it back to the ?On? position, without first verifying that the area is clear.
Or does the key stay in the machine, and does the process of removing the key turn the machine off, and so long as the key is in someone?s pocket the machine cannot be used? This might be safe, but only if there is only one key.
Or is it that a person can take the key out of a pocket, use the key to turn off the machine, and then place the key back in the pocket. This might also be safe, but only if there is only one key.
If either of the later two situations, it would be extraordinarily dangerous for there to be more than one key.
The only way to make something like this safe is for the people reaching into the machine to be able to see, in their immediate vicinity, physical evidence that the machine is locked out, and that the machine cannot be unlocked until that ?physical evidence? is no longer in their immediate vicinity. Think of it like the disconnect device that is required to be accessible to, and in full view of, a maintenance person who is working on an outdoor air conditioning unit. That worker will remove the disconnect, and can see the open disconnect for all the time that the work is going on. But if the disconnect were out of sight, and if there were two plugs that could restart the a/c unit, would you trust that no person will use the second plug while your hands are in the unit?
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: key switches
The National Electrical Code has nothing to say on this question. Perhaps there is something in the OSHA rules?
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: key switches
</font>
Is this what you mean:
</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Let us assume there are two keys.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Both keys are kept in their respective locks.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Removal of either key would disable the machine.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">If I think I can clear the jam alone, I will grab one key, put it in my pocket, and go to work, knowing that the machine is locked out.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Then if I think I need help, I call you, and you will grab the second key, and put it in your pocket.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The machine cannot be restarted unless both of us go to where the locks are located, remove the keys from our pockets, and put them back in the locks.</font>
Re: key switches
OSHA requires there to be a physical break in the connection, I. E. ckt, breaker, fuse removable, disconnect switch. A push button, lockable or not is not sufficient. OSHA also requires each man working on the piece of equipment to have his own lock.
Sorry I can't quote the reg #, I have a hard enough time with NEC #'s. OSHA lock out procedures is where you need to look. I believe there is an OSHA.gov web page that can lead you in the right direction.
Edit: try here http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9804. There are even exeptions you may be able to aply that can justify not needing a lockout but your management must make decision and there needs to be a defined procedure for clearing jams.
[ May 13, 2005, 04:22 PM: Message edited by: 69boss302 ]
OSHA requires there to be a physical break in the connection, I. E. ckt, breaker, fuse removable, disconnect switch. A push button, lockable or not is not sufficient. OSHA also requires each man working on the piece of equipment to have his own lock.
Sorry I can't quote the reg #, I have a hard enough time with NEC #'s. OSHA lock out procedures is where you need to look. I believe there is an OSHA.gov web page that can lead you in the right direction.
Edit: try here http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9804. There are even exeptions you may be able to aply that can justify not needing a lockout but your management must make decision and there needs to be a defined procedure for clearing jams.
[ May 13, 2005, 04:22 PM: Message edited by: 69boss302 ]
Re: key switches
Thanks for the replys. Here is an eample of what happens. We have a large amchine and it may have a jam in the machine. The operator removes a keyswitch that disables that part of the machine from working as long as the keyswitch has been turned to the off position. The operator removes the key and puts it in his pocket and then procedes to climb on the machine to remove the jam , he may or not have another person helping him working under his key protection with out any other protection. When the work is completed operator one takes key and turns machine back to working condition. I have concerns about this procedure but have been told that it is ok by (osha)for that to happen as long as we are not "working" on the machine. (thanks for your input to this question)
Thanks for the replys. Here is an eample of what happens. We have a large amchine and it may have a jam in the machine. The operator removes a keyswitch that disables that part of the machine from working as long as the keyswitch has been turned to the off position. The operator removes the key and puts it in his pocket and then procedes to climb on the machine to remove the jam , he may or not have another person helping him working under his key protection with out any other protection. When the work is completed operator one takes key and turns machine back to working condition. I have concerns about this procedure but have been told that it is ok by (osha)for that to happen as long as we are not "working" on the machine. (thanks for your input to this question)
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: key switches
I believe that for the original post, a lockable mushroom E-Stop button is sufficient for their purposes. A jam is not a maintenance task, it is a momentary shutdown of a machine while production is under way.
) It's a 12-into-1 inserter, which means up to 16 people could be manning this machine at one time. Jams do happen, and the means by which the are cleared is that each worker has a muchroom E-stop at their "pocket" or station. If someone hits an E-stop, that E-stop must be reset before the machine will start again. After the E-stop reset, any pocket can restart the machine, but the PLC delays motion for 3 seconds after the warning bell sounds.
Edit: Actually, in addition to the E-stop, there is a momentary stop switch that is more readily accessible. The momentary stop switch will stop the inserter. If anyone else needs to reach into the machine for any reason, then they too can press the momentary stop button. A red light goes on at the top of every pocket (you might just barely see them in the photo), and the last person to press the green (start) button would cause their red-light to clear, the warning bell to sound and the machine would restart. It was kinda cool to see it in action, kind of a NASA Go/No-Go vibe going on.
Anyway, a jam isn't necessarily a LOTO event.
[ May 13, 2005, 05:06 PM: Message edited by: georgestolz ]
When I worked in production at the local newspaper, I worked on machines that jammed with regularity. (Not that they were constantly jamming, but it wasn't exactly an event when it happened.)
I believe that for the original post, a lockable mushroom E-Stop button is sufficient for their purposes. A jam is not a maintenance task, it is a momentary shutdown of a machine while production is under way.
) It's a 12-into-1 inserter, which means up to 16 people could be manning this machine at one time. Jams do happen, and the means by which the are cleared is that each worker has a muchroom E-stop at their "pocket" or station. If someone hits an E-stop, that E-stop must be reset before the machine will start again. After the E-stop reset, any pocket can restart the machine, but the PLC delays motion for 3 seconds after the warning bell sounds.Edit: Actually, in addition to the E-stop, there is a momentary stop switch that is more readily accessible. The momentary stop switch will stop the inserter. If anyone else needs to reach into the machine for any reason, then they too can press the momentary stop button. A red light goes on at the top of every pocket (you might just barely see them in the photo), and the last person to press the green (start) button would cause their red-light to clear, the warning bell to sound and the machine would restart. It was kinda cool to see it in action, kind of a NASA Go/No-Go vibe going on.
Anyway, a jam isn't necessarily a LOTO event.
[ May 13, 2005, 05:06 PM: Message edited by: georgestolz ]
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Re: key switches
It "might" be ok. It's one of those things that depends on a lot of information we don't have.
Presumably, the key is not just a key switch but a safety key, where removal of the key prevents motion in that section of the machine while the key is removed.
Personally, I would want to see 2 keys if there were two people working on unjamming at the same time, but you might be able to concoct a situation where a single key and multiple people was acceptable. One case would be where the key is used to open a guard ,and as long as someone was inside the guard the guard could not be physically closed (such as being forced to work through the opening the guard coveres), and the key cannot be physically reinserted until the guard is closed.
I am not sure OSHA "approves" such arrangements anyway. I never heard of them doing so. It's not like you can call in your local OSHA inspector and have him approve your safety plan and sign off on it.
It "might" be ok. It's one of those things that depends on a lot of information we don't have.
Presumably, the key is not just a key switch but a safety key, where removal of the key prevents motion in that section of the machine while the key is removed.
Personally, I would want to see 2 keys if there were two people working on unjamming at the same time, but you might be able to concoct a situation where a single key and multiple people was acceptable. One case would be where the key is used to open a guard ,and as long as someone was inside the guard the guard could not be physically closed (such as being forced to work through the opening the guard coveres), and the key cannot be physically reinserted until the guard is closed.
I am not sure OSHA "approves" such arrangements anyway. I never heard of them doing so. It's not like you can call in your local OSHA inspector and have him approve your safety plan and sign off on it.
Re: key switches
Application.
1910.147(a)(2)(i)
This standard applies to the control of energy during servicing and/or maintenance of machines and equipment.
1910.147(a)(2)(ii)
Normal production operations are not covered by this standard (See Subpart O of this Part). Servicing and/or maintenance which takes place during normal production operations is covered by this standard only if:
1910.147(a)(2)(ii)(A)
An employee is required to remove or bypass a guard or other safety device; or
1910.147(a)(2)(ii)(B)
An employee is required to place any part of his or her body into an area on a machine or piece of equipment where work is actually performed upon the material being processed (point of operation) or where an associated danger zone exists during a machine operating cycle.
Note: Exception to paragraph (a)(2)(ii): Minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection (See Subpart O of this Part).
Next Parts are from different section:
An employee is required to place any part of his or her body into an area on a machine or piece of equipment where work is actually performed upon the material being processed (point of operation) or where an associated danger zone exists during a machine operating cycle.
Note: Exception to paragraph (a)(2)(ii): Minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection (See Subpart O of this Part).
Energy isolating device. A mechanical device that physically prevents the transmission or release of energy, including but not limited to the following: A manually operated electrical circuit breaker; a disconnect switch; a manually operated switch by which the conductors of a circuit can be disconnected from all ungrounded supply conductors, and, in addition, no pole can be operated independently; a line valve; a block; and any similar device used to block or isolate energy. Push buttons, selector switches and other control circuit type devices are not energy isolating devices.
Servicing and/or maintenance. Workplace activities such as constructing, installing, setting up, adjusting, inspecting, modifying, and maintaining and/or servicing machines or equipment. These activities include lubrication, cleaning or unjamming of machines or equipment and making adjustments or tool changes, where the employee may be exposed to the unexpected energization or startup of the equipment or release of hazardous energy.
These are off of the OSHA web site right out of the reg. But there are exceptions. Depends on what the person has to do to unjam the machine. I would say if he is climbing on it, it should be locked out.
Application.
1910.147(a)(2)(i)
This standard applies to the control of energy during servicing and/or maintenance of machines and equipment.
1910.147(a)(2)(ii)
Normal production operations are not covered by this standard (See Subpart O of this Part). Servicing and/or maintenance which takes place during normal production operations is covered by this standard only if:
1910.147(a)(2)(ii)(A)
An employee is required to remove or bypass a guard or other safety device; or
1910.147(a)(2)(ii)(B)
An employee is required to place any part of his or her body into an area on a machine or piece of equipment where work is actually performed upon the material being processed (point of operation) or where an associated danger zone exists during a machine operating cycle.
Note: Exception to paragraph (a)(2)(ii): Minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection (See Subpart O of this Part).
Next Parts are from different section:
An employee is required to place any part of his or her body into an area on a machine or piece of equipment where work is actually performed upon the material being processed (point of operation) or where an associated danger zone exists during a machine operating cycle.
Note: Exception to paragraph (a)(2)(ii): Minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection (See Subpart O of this Part).
Energy isolating device. A mechanical device that physically prevents the transmission or release of energy, including but not limited to the following: A manually operated electrical circuit breaker; a disconnect switch; a manually operated switch by which the conductors of a circuit can be disconnected from all ungrounded supply conductors, and, in addition, no pole can be operated independently; a line valve; a block; and any similar device used to block or isolate energy. Push buttons, selector switches and other control circuit type devices are not energy isolating devices.
Servicing and/or maintenance. Workplace activities such as constructing, installing, setting up, adjusting, inspecting, modifying, and maintaining and/or servicing machines or equipment. These activities include lubrication, cleaning or unjamming of machines or equipment and making adjustments or tool changes, where the employee may be exposed to the unexpected energization or startup of the equipment or release of hazardous energy.
These are off of the OSHA web site right out of the reg. But there are exceptions. Depends on what the person has to do to unjam the machine. I would say if he is climbing on it, it should be locked out.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: key switches
That's probably a good rule of thumb. This is coming from a guy with two crushed fingers from the machines I mentioned above.
- Location
- Massachusetts
Re: key switches
A lockable E-stop is not adequate.
From 69boss302 post of the OHSA requirements.
It is to OSHA if you are placing your body parts in harms way.Originally posted by georgestolz:
Anyway, a jam isn't necessarily a LOTO event.
A lockable E-stop is not adequate.
From 69boss302 post of the OHSA requirements.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Re: key switches
However, a safety relay is. And it can be controlled by a key system. Maybe not your basic keyed selector switch though.
This is a case where the thing requires some thinking and a proper safety review before making a determination as to just what is appropriate.
I can say though, that it is very common to have some provision for this type of thing that does not require shutting down the whole machine.
However, a safety relay is. And it can be controlled by a key system. Maybe not your basic keyed selector switch though.
This is a case where the thing requires some thinking and a proper safety review before making a determination as to just what is appropriate.
I can say though, that it is very common to have some provision for this type of thing that does not require shutting down the whole machine.
Re: key switches
Thanks for the replies again . Thanks for the websites to look at what OSHA has to say. I have suggested to our safety group that we look again how we use the keyswitch to allow people to enter to do minor servicing. Right now we allow more than one person to enter the machine to pull out paper jams by pulling a designated key from a switch that opens a circuit at that particular part of the machine. That part of the machine will not start as long as the key is pulled. We allow this only for paper jams, not for work. My question is do we allow more than one person to work under one key switch. After this discussion I think I will be able to convince others that we should find a way to change our policy and not have 4 people relying on one key to protect them when its in someone elses pocket even though its minor servicing.
Thanks for the replies again . Thanks for the websites to look at what OSHA has to say. I have suggested to our safety group that we look again how we use the keyswitch to allow people to enter to do minor servicing. Right now we allow more than one person to enter the machine to pull out paper jams by pulling a designated key from a switch that opens a circuit at that particular part of the machine. That part of the machine will not start as long as the key is pulled. We allow this only for paper jams, not for work. My question is do we allow more than one person to work under one key switch. After this discussion I think I will be able to convince others that we should find a way to change our policy and not have 4 people relying on one key to protect them when its in someone elses pocket even though its minor servicing.
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