Nuances of 1910.147 & 1910.333 deenergization verifications

[cdevine]

I'd be interested in hearing what the proposed solution is like. There may be elements of it I can take back to my areas.

First a disclosure. I am involved in the development of the solution and as this is a no advertising forum (as it should be) I will provide some hints as to the solution rather than website links to the information.

The solution we have been working on is a voltage indicator that includes a self test function. It achieves a high integrity result when operated identical to the live-dead-live method. The device is different in that it illuminates a green LED when the circuit is off (positive indication) and its measurement circuit does not make a direct connection to the power system (reduced risk of device failure and subsequent arc flash).

Forums such as this allow people with like minds to identify common problems and thrash out possible solutions. Thank you for initiating this thread WarAxe. Its very educational for me and I know discussions like this foster innovation.

 

[don_resqcapt19]

First a disclosure. I am involved in the development of the solution and as this is a no advertising forum (as it should be) I will provide some hints as to the solution rather than website links to the information.

The solution we have been working on is a voltage indicator that includes a self test function. It achieves a high integrity result when operated identical to the live-dead-live method. The device is different in that it illuminates a green LED when the circuit is off (positive indication) and its measurement circuit does not make a direct connection to the power system (reduced risk of device failure and subsequent arc flash).

Forums such as this allow people with like minds to identify common problems and thrash out possible solutions. Thank you for initiating this thread WarAxe. Its very educational for me and I know discussions like this foster innovation.

There is a device on the market that is very similar to that and it is my understand that there is a letter ruling from OSHA that says that device cannot be used in place of live-dead-live testing.

 

[cdevine]

There is a device on the market that is very similar to that and it is my understand that there is a letter ruling from OSHA that says that device cannot be used in place of live-dead-live testing.

Agree 100%. This device is suitable for verification prior to mechanical work only. Incidentally, which happens to be the most frequent reason why isolations are performed.

 

[WarAxe]

Agree 100%. This device is suitable for verification prior to mechanical work only. Incidentally, which happens to be the most frequent reason why isolations are performed.

Yeah, having a method OSHA would accept for the 147 verification that would satisfy a few of the outlier scenarios (interlocks, known broken controls) would be good.

And overall you guys are hitting on what I think is the key principle in a lot of this... workers need to understand their equipment and why they're taking the steps they are for their own safety.

 

[umichEE]

Agree 100%. This device is suitable for verification prior to mechanical work only. Incidentally, which happens to be the most frequent reason why isolations are performed.

I disagree. OSHA is pretty clear that an LED is not an acceptable verification for 1910.147 work in the following standard interpretation:

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=28829

"Question 1: Can the type of device described above be used to verify that isolation and deenergization of the machine or equipment have been accomplished under 29 CFR 1910.147(d)(6)?

Response: No. However, the type of device that you describe, if installed correctly and maintained, might serve only as a redundant indicator that the disconnecting device is in the open ("off") position."

 

[cdevine]

I disagree. OSHA is pretty clear that an LED is not an acceptable verification for 1910.147 work in the following standard interpretation:

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=28829

"Question 1: Can the type of device described above be used to verify that isolation and deenergization of the machine or equipment have been accomplished under 29 CFR 1910.147(d)(6)?

Response: No. However, the type of device that you describe, if installed correctly and maintained, might serve only as a redundant indicator that the disconnecting device is in the open ("off") position."

Thank you umichEE. I agree, OSHA has taken a firm position on this topic. As you may have read in earlier posts in this thread OSHA's logic may not be entirely bullet proof. Some designers may take comfort knowing that their approach is legally OK. Other designers may be more comfortable knowing that their approach is the safest.

I do agree that the device referred to in the above link "... the LED device is connected to the disconnecting device such that it should illuminate when any individual phase is energized" and presumably extinguish when any individual phase is de-energized, is not particularly fail safe. The device referred to in an earlier post...

"The solution we have been working on is a voltage indicator that includes a self test function. It achieves a high integrity result when operated identical to the live-dead-live method. The device is different in that it illuminates a green LED when the circuit is off (positive indication) and its measurement circuit does not make a direct connection to the power system (reduced risk of device failure and subsequent arc flash)."

is a different device altogether.

 

[WarAxe]

I disagree. OSHA is pretty clear that an LED is not an acceptable verification for 1910.147 work in the following standard interpretation:

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=28829

"Question 1: Can the type of device described above be used to verify that isolation and deenergization of the machine or equipment have been accomplished under 29 CFR 1910.147(d)(6)?

Response: No. However, the type of device that you describe, if installed correctly and maintained, might serve only as a redundant indicator that the disconnecting device is in the open ("off") position."

Depends, though. OSHA was clearly saying that LEDs (or other indicating lights) on the energy isolation device cannot be used to provide 147(d)(6) verification of the inability for the downstream device to be inadvertently energized.

However, that doesn't mean that LEDs (or other indicating lights) located downstream at the device (say, a "power available" light on a motor controller) cannot be used.

 

[cdevine]

Some might say that the reasoning in the interpretation is flawed eg....

[FONT=Tahoma, Verdana, Helvetica, sans-serif]"One effective method of compliance would be a deliberate attempt by an authorized employee to start up the equipment, which should not be capable of activation because of the application of the energy control devices."[/FONT]

[FONT=Tahoma, Verdana, Helvetica, sans-serif]or perhaps there is a control circuit fault or that the motor shaft is jammed. Mmmmm.....effective method? It's true, this approach helps to identify when the wrong equipment has been isolated but identify a faulty isolation? Perhaps not! This could be why the interpretation goes onto say....

[/FONT]"The use of a test instrument is particularly applicable for verifying isolation and deenergization in the case of jammed equipment..."

So to try and paraphrase, verification is about:

1. Knowing that the correct equipment has been isolated, and
2. Knowing that the equipment has been correctly isolated

Try Start addresses 1. A live-dead-live check addresses 2. A process operator can perform a Try Start OK but he/she cannot perform a live-dead-live check.

Some people believe that a simple LED device is not fail-safe and cannot be used to perform a live-dead-live check sequence.
[FONT=Tahoma, Verdana, Helvetica, sans-serif]
[/FONT]Providing a tool that a process operator can use to achieve a high integrity, test result identical to that achieved by a live-dead-live check has been my focus.