Verifying "Presence of Voltage" Prior to LOTO

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PhilipAtWallops

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Location
Wallops Island, VA
Per OSHA Lock Out Tag Out (LOTO) Requirements,

The proper sequence for de-energizing equipment is as follows:
1. Prepare for shutdown
2. Machine or equipment shutdown
3. Machine or equipment isolation
4. Lockout or tagout device application
5. Stored energy removal
6. Verification of Isolation (absence of voltage test)

Is confirming the presence of voltage on the circuit to be de-energized prior to LOTO allowed? Seems that confirming the presence of voltage prior to LOTO would confirm that the meter is working properly and would confirm that the correct circuit is actually locked and tagged out...

Anyone ever run across this?
 
I don't understand your question. Why would you comfirm voltage before shutting down?

Most pieces of equimpment require documented LO/TO procedures, which will include the verification check at the end. Like any task you do with a MM, you should check the meter on a known source.

As an example, we have dozens of different types of machines, from large presses, lathes, etc. In order to perform maintenance, the qualified technician is required to follow the written procedures for LO/TO for that specific piece of equipment. If it just requires the worker to throw a knife switch, he will do that, lock/tag the switch out and verify its shut down. The verification maybe taking readings on his MM in the control panel, or attempting to start the machine. If he is taking voltage measurements with the MM, he will be wearing the proper PPE until it's deamed safe.
 
WorkSafe said:
I don't understand your question. Why would you comfirm voltage before shutting down?
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We're not so concerned about individual equipment because the safety disconnects are within line of site and the circuits are usually obvious. We're more concerned about LOTO on branch circuits in main distribution panels, subfeeds and MV work. When you can see the disconnect and are confident about the circuitry, it's not as big a deal.

Our issue is that we're responsible for a federal facility that has dozens of old buildings and virtually worthless panel schedules. When doing work on a circuit, confirming voltage before and after LOTO confirms that the meter works and that you've locked out the correct circuit. On MV work, it's absolutely necessary to confirm that the meter is operational. Does this make sense?
 
Makes sense.

To answer your question, you can check power before LO/TO, however, you need to determine your PPE level when doing this check as well, and that the appropriate meter is being used for the voltage, etc. Might just be HRC 0, but need to know.
 
sii said:
I thought this was not an acceptable method to check for voltage?
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It depends what we are locking it out for. It is a acceptable method in the industrial world if working on a machine when checking to ensure there would be no unexpected startup.
 
Verifing meter operation does not have to be on a different source, you are just verifing the meter is working correctly, and I see no reason that you could not test it on a known voltage source before turning it off, even if it's the one your eventually turning off.
 
hillbilly1 said:
Verifing meter operation does not have to be on a different source, you are just verifing the meter is working correctly, and I see no reason that you could not test it on a known voltage source before turning it off, even if it's the one your eventually turning off.
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That would be fine, but we still would have to confirm that the meter works on an energized circuit after the one in question is show to be deenergized.
 
PhilipAtWallops said:
The troubling part for us is that testing for voltage prior to shutting down is not listed in the OSHA steps for LOTO...
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Doesn't have to be listed in the OSHA steps. You're always allowed to exceed OSHA expectations. You just can't do less.

In an old building with poor documentation it'd be a good practice to check before and after. Treat it as energized for troubleshooting until you verify it's truly disconnected as expected. And don't skip the other steps either.
 
sii said:
I thought this was not an acceptable method to check for voltage?
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You're correct attempting to start the equipment does not satisfy the OSHA requirement of verifying that the power is effectively locked out, hence the need for testing the SOURCE of the power directly. A visible break in the conductive path of the power is also acceptable such as an empty fuseholder or visible parting of the main disconnecting means. Both European equipment nmanufacturers and Squared D in the US marketed molded case circuit breakers and MCP's that had a Lexane(/) covered window through which the main contacts can be observed, but it did not 'take' so I think that they have largely abandoned those.
 
pfalcon said:
Doesn't have to be listed in the OSHA steps. You're always allowed to exceed OSHA expectations. You just can't do less.

In an old building with poor documentation it'd be a good practice to check before and after. Treat it as energized for troubleshooting until you verify it's truly disconnected as expected. And don't skip the other steps either.
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I think that the better answer is that OSHA will define the objective and lets the public define HOW that objective will be met. Then the public can offer various solutions and verify those with OSHA that they are acceptable solutions or not. Trying to start the equipment and locking out the control circuit were both formally rejected by OSHA, in a form of letter, as a means of complying with the objective.
 
Volta said:
That would be fine, but we still would have to confirm that the meter works on an energized circuit after the one in question is show to be deenergized.
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That would be tough to do if you completely de-energizing something like a service, are you going to walk across the street to check your meter again at another power source? Some things are not practical.:)
 
hillbilly1 said:
That would be tough to do if you completely de-energizing something like a service, are you going to walk across the street to check your meter again at another power source? Some things are not practical.:)
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Hadn't really thought about it but ... does it have to be the same type of power source or does a flashlight battery work?
 
pfalcon said:
Hadn't really thought about it but ... does it have to be the same type of power source or does a flashlight battery work?
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The flashlight battery would be DC, hence a different setting, so it would not verify the ac setting was actually working, only that your leads were good. Just one of those catch 22 things.:)
 
PhilipAtWallops said:
The troubling part for us is that testing for voltage prior to shutting down is not listed in the OSHA steps for LOTO...
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If you check 1910.333(b)(2)(iv) "If the circuit is over 600 volts nominal, the test equipment shall be checked for proper operation immediately before and immediately after this test". Whatever the voltage is, if I have to stick my hands into a piece of equipment that is suppose to be dead, I will do the live-dead-live test.
 
weressl said:
I think that the better answer is that OSHA will define the objective and lets the public define HOW that objective will be met. Then the public can offer various solutions and verify those with OSHA that they are acceptable solutions or not. Trying to start the equipment and locking out the control circuit were both formally rejected by OSHA, in a form of letter, as a means of complying with the objective.
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I was getting a little off topic when I mentioned "attempt to start equipment" when verifying isolation. I was referring to OSHA 1910.147, and not 1910.333.

OSHA does permit a authorized person to attempt to start the machine in order to verify it has been successfully LO/TO, but, if I were a electrician working inside of ELECTRICAL equipment, I would need to follow the steps in 1910.333 and verify voltage, etc.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=9805&p_table=STANDARDS


Type(s) of stored energy - methods to dissipate or restrain.

(7) Ensure that the equipment is disconnected from the energy source(s) by first checking that no personnel are exposed, then verify the isolation of the equipment by operating the push button or other normal operating control(s) or by testing to make certain the equipment will not operate.

Caution: Return operating control(s) to neutral or "off" position after verifying the isolation of the equipment.

________________________

Method of verifying the isolation of the equipment.

(8) The machine or equipment is now locked out.
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richxtlc said:
If you check 1910.333(b)(2)(iv) "If the circuit is over 600 volts nominal, the test equipment shall be checked for proper operation immediately before and immediately after this test". Whatever the voltage is, if I have to stick my hands into a piece of equipment that is suppose to be dead, I will do the live-dead-live test.
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Aslo check NFPA 70E (2012) 110.4(A)(5) and 120.1(5)
 
hillbilly1 said:
That would be tough to do if you completely de-energizing something like a service, are you going to walk across the street to check your meter again at another power source? Some things are not practical.:)
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Agreed. Yesterday I verified meter on 120vac after disconnecting 480, but I would only walk so far too ... ;)
 
richxtlc said:
1910.333(b)(2)(iv) "If the circuit is over 600 volts nominal, the test equipment shall be checked for proper operation immediately before and immediately after this test". Whatever the voltage is, if I have to stick my hands into a piece of equipment that is suppose to be dead, I will do the live-dead-live test.
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The importance of checking the test equipment, whether it be a meter or tic tracer, both before AND after use can't be underestimated. It's the only way to be absolutely sure that the device you use to protect your life and livelihood actually works.
 
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