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 Post subject: Energized work in lockout procedures and clause 4.3.2.2
PostPosted: Mon Mar 24, 2014 8:43 am 

Joined: Mon Mar 24, 2014 6:25 am
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From my understanding, energized work is forbidden with the exception of the three following clauses (4.3.2.2):
  1. Additional hazards or increased risk (4.3.2.2.1)
  2. Infeasibility (4.3.2.2.2)
  3. De-energizing at less than 50V (4.3.2.2.3)

If the energized work falls within one of the three exception clauses, then an energized work permit (4.3.2.3) must be issued except for the exemptions to work permit found in clause 4.3.2.3.3.

A qualified worker can then undertake energized electrical work within the limited approach boundary wearing the appropriate PPE.

I have personally not found up to now a clause in the Z462-12 that indicates a distinction between energized tasks. Lists of common tasks are included in Z462-12 table 4A.

When establishing an electrically safe work condition lockout procedure must be used to de-energize equipment. Most lockout procedures involve breaker operation, switch operation and breaker racking.

How can lockout procedures be executed if energized work such as breaker operation, switch operation and breaker racking are not in the exception clauses of 4.3.2.2.

In other words, how is an electrically safe working condition to be achieved if the lockout procedure to attain to the safe working condition is considered to be energized work and it is forbidden because it doesn`t fall under the exemptions found in clause 4.3.2.2?

thanks!


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PostPosted: Mon Mar 24, 2014 11:58 pm 
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I don’t think you must see that kind of energized work as forbidden. It is more like until you verified that it is de-energized you must assume it is NOT so wear appropriate PPE.

In the NFPA70E 2012 edition annex G Sample lockout/tagout procedure, there is no mention of needing a energized work permit.

Annex J figure J.2 is a flow chart that shows that when you want to lockout/tagout equipment you must follow the lockout/tagout procedures the energized electrical work permit is not required.


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PostPosted: Tue Mar 25, 2014 6:46 am 

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Thank you for your reply Luc.

Up until recently, I have always thought that we can use detailed arc flash IE results or the table 4A to know the PPE for common tasks such as breaker operation, switch operation and breaker racking. The electricians have proper training and wear the proper PPE and the common task can be done safely.

At my workplace, we recently got into discussions about racking in and out 45 year old circuit breakers. Opinions on the subject diverged and I was asked to look into the CSA Z462-12 (Canadian version of NFPA 70E-2012) for some guidance.

I also sent an email to the CSA project manager for guidance. He was very generic and basically said the standard made no distinction among common operation tasks and energized work (Both are contained in the table 4A). The project manager referred me to clause 4.3.2.2. If I paraphrase it says: the energized work (or common operation task, because the standard doesn’t appear to make distinctions between the two) are forbidden with the exception to the three following clauses:
1. Additional hazards or increased risk (4.3.2.2.1)
2. Infeasibility (4.3.2.2.2)
3. De-energizing at less than 50V (4.3.2.2.3)

Up to now, I have found no clauses in Section 4 Safety-related work pratices that allows for lock-out procedures to be done without energized work permits.

Annex G and Annex J are informative and not a mandatory part of the standard. Annex J (flow chart) seems to provide additional information not provided in the mandatory part of the standard, and thus in certain regards, seems to contradict it as for when an electrical work permit is required.


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PostPosted: Tue Mar 25, 2014 7:33 am 
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Look at the exception clause that was added just after 4.3.2.2 in the 2012 edition. Previously the arrangement of the paragraphs was significantly different. You had section 2 which specified that if LOTO is being performed, follow section 3. If it is energized work, follow section 4. There were two issues and thus the changes in the 2012 edition. First, the previous edition only evoked the energized work permit for shock hazards. Arc flash hazards were not considered. Second, the rules specific to the hazards were contained in section 4, not section 3. Strictly speaking although hazard analysis was required in section 2 regardless of the work, there were no corresponding rules for dealing with hazards in section 3.

Thus the material in section 2 was moved to section 4. Arc flash boundaries were also added to the energized work rule. At this point section 3 now stands alone since it only applies more or less in conjunction with section 4 while de-enerigizing activities are going on. This solved the issues, at least partly. The trick here of course is that you have to interpret when the hazards exist (see definitions section for arc flash hazard, and exposed definitions for shock hazards). The shock hazard definitely does not exist while operating a switching device with the doors closed and latched for instance. The arc flash hazard MAY exist but we get into the interpretational soup of "interaction". Appealing to the task tables which is what the definition seems to suggest is no help either. So there is no way out using the sections that you have looked at so far.

You can't de-energize to perform de-energized work unless at some point the work is actually energized. Previously this did not arise because you were either performing LOTO and thus ignore the energized work permit issue, or you are performing energized work in which case either it applies or the diagnostic work exception(s) apply, or you use a tortured interpretation of the diagnostic exception such as calling all switching activities "startup" work. So a new exception was added right after section 4.3.2.2 which I believe is supposed to "fix" the problem of merging section 2 into section 4 material by allowing an out for energizing and de-energizing equipment (switching).

At least that's my interpretation...the exception is one of the most convoluted and impossible to read, tortured paragrpahs in the entire standard. I submitted a comment on this paragraph to make it more readable for the 2015 edition but my comment was rejected by the committee. Apparently they like the lawyerized version that is impossible to read. The complete text of the exception for you to try to analyze is as follows:

"Exception: Where a disconnecting means or isolating element that has been properly installed and maintained is operated, opened, closed, removed, or inserted to achieve an electrically safe work condition for connected equipment or to return connected equipment to service that has been placed in an electrically safe work condition, the equipment supplying the disconnecting means or isolating element shall not be required to be placed in an electrically safe work condition, provided a risk assessment is performed and does not identify unacceptable risks for the task."

My interpretation is as follows:
Clause 1: "Where a disconnecting means or isolating element that has been properly installed and maintained is operated, opened, closed, removed, or inserted to achieve an electrically safe work condition for connected equipment or to return connected equipment to service that has been placed in an electrically safe work condition,"
In other words if you are place/return equipment in an electrically safe work condition.
Clause 2: "the equipment supplying the disconnecting means or isolating element shall not be required to be placed in an electrically safe work condition"
In other words, ignore the energized work permit rule.
Clause 3: "provided a risk assessment is performed and does not identify unacceptable risks for the task."
Risk assessment is required for this task. Risk assessment is later required for ALL energized tasks anyways. This clause is redundant.

If the exception consisted simply of clause 2 with just a little more context, it would have been far more clear.

The alternative would be to issue an energized work permit every time for all switching tasks. The clear reason for doing so would be infeasibility, or perhaps to claim that doing a task de-energized is less of a risk than the risk that de-energizing itself would impose. Although there are many times where I believe that the latter interpretation is in fact correct such as when de-energizing high incident energy panelboards vs. landing plug-in breakers, this should be the exception rather than the rule.

However from a very practical point of view, let's consider the result. If we in fact require an energized work permit for ALL electrical work, whether it involves energized work or de-energizing to perform the work, then issuance of the permit will become automatic and routine. Dare I say it, nobody is going to be paying any attention whatsoever to the permit at all. The entire purpose of the permit in the first place is an administrative control...to require someone to spend the time determining whether or not the task can be done de-enerigized in the first place. And second, that the second party which is actually authorizing the permit is management and is acknowledging their responsibility in allowing what is known to be a hazardous task to occur, and that there are no practical alternatives. Someone in the decision loop should be taking a look at the criteria for the hazard and making an interpretation that there is just no good alternative. If we just start requiring energized permits for all tasks, then that particular aspect of the rules will be completely ignored. Issuance of energized work permits should definitely be the exception and not the rule. That is clearly not the intent.

So...choose your poison. Either allow a "4th exception" for switching tasks, which appears to be what the exception paragraph means, or torture the "startup" exception. Regardless, from a practical point of view, this is necessary.


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PostPosted: Tue Mar 25, 2014 10:21 am 

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PaulEngr wrote:

"Exception: Where a disconnecting means or isolating element that has been properly installed and maintained is operated, opened, closed, removed, or inserted to achieve an electrically safe work condition for connected equipment or to return connected equipment to service that has been placed in an electrically safe work condition, the equipment supplying the disconnecting means or isolating element shall not be required to be placed in an electrically safe work condition, provided a risk assessment is performed and does not identify unacceptable risks for the task."


I can`t find this exception in the CSA Z462-12. It is in the NFPA 70E 2012 though.


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PostPosted: Tue Mar 25, 2014 10:24 am 

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Sorry for the length of this post and I thank you in advance for any help that may be provided.

I would like to push this discussion a little bit further with an example.

Suppose the single-line diagram at the plant I work for is identical to the one found in Figure D.1 Annex D. Let’s also assume all the circuit breakers in the 13.8 kV Bus 1A and Bus 1B can be remotely operated from a control room.

Lets suppose I want to isolate the 2.5 MVA 13.8/0.6 kV transformer that feeds Bus 5B 600 V. All the parameters are respected to use table 4A for hazard risk category.

Classically, I would:

1. Open all the feeders on Bus 5B; (HRC 0 using table 4A)
2. Open and lock out the main fused switch feeding Bus 5B (secondary side of transformer). Make sure all blades are fully open; (HRC 0 using table 4A)
3. Close the tie switch between bus 5A and bus 5B; (HRC 0 using table 4A)
4. Close all the feeders on bus 5B; (HRC 0 using table 4A)
5. Open and lockout the fused switch located at bus 1B feeding the 2.5 MVA transformer. Make sure all blades are fully open; (HRC 2 using table 4A)
6. Before work is done, test each phase with a voltage detector and apply ground-connecting devices if judged necessary. (HRC 4 using table 4A)


Applying clause 4.3.2.2 Energized work to my lock out procedure:

4.3.2.2.1 Additional hazards or increased risk
“Energized work may be performed when the employer can demonstrate that de-energizing introduces additional hazards or increased risk.”

Does not apply to the lock out procedure.

4.3.2.2.2 Infeasibility
Energized work may be performed when the employer can demonstrate that the task to be performed is infeasible in a de-energized state because of equipment design or operational limitations.”

Might possibly apply to the lock out procedure as operational limitations. An energized work permit could be issued and work can be undertaken.

But in this case, you can remotely operate the circuit breaker at the 13.8 kV Bus 1A. In theory, the circuit breaker can be remotely opened and the lockout procedure can be undertaken on equipment that is de-energized eliminating the risks for the electricians.

The downfall is that opening the circuit breaker with load current puts stress on the circuit breaker. Another downfall is that a major portion of the plant gets de-energized while the lockout procedure is being done.

4.3.2.2.3 De-Energizing at less than 50 V
“Energized electrical conductors and circuit parts that operate at less than 50 V shall not be required to be de-energized when the capacity of the source and any overcurrent protection….”

Does not apply to the lock out procedure.


I am seeking advice on this issue.

For any industrial plant it is preferable to go the classical way. Less equipment goes out of service and less stress on the circuit breaker operating on load currents.

On the other hand, remotely opening the circuit breaker and performing the lockout procedure on already de-energized equipment eliminates most, if not all, electrical hazard risks.

As for energized work permits, I have read a tip (Chet Davis, ESM Aug. 2007) about long standing energized work permits for operating switches as part of the process in a industrial plant. The permit is developed covering all switch operations for specific equipment. Each employee should then be trained and qualified for that standing work permit on that class of equipement. It avoids the perceived problem of issuing work permits for each operation of equipment.

Any thoughts, comments or advice on this?


Thanks,


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PostPosted: Wed Mar 26, 2014 1:29 pm 
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1. No permit needed if you have remote open/close functions. At this point you are operating equipment and not within either the arc flash or limited approach boundaries so no PPE needed. Not H/RC 0...none needed. Once you go to test (step 5), this is diagnostic work. There is already an exception for this in both 70E and CSA Z462. This exception has been there for a long time. It follows the energized work permit rule. So no, no permit needed for this. When it comes to applying grounds though, this would definitely be altering the circuit so no exception there. The greater hazard rule definitely can apply because working live on medium voltage is far more risky than installing the ground and taking the relatively low risk one time, so both this and the infeasibility clauses apply. At this point the circuit tests dead though so technically I'm not sure if you can even say that this is doing "energized work" since it has already been tested dead. As you know the purpose of installing grounds is to prevent induced voltages, another layer of protection against accidental energization even naturally occurring ones (lightning), and to drain off any residual charges in the system to provide an equipotential work zone. If you follow the Z462 procedure, you test first then ground. I have no idea what to do if you actually detect induced voltage under Z462. Under IEEE C2 (NESC) and similar procedures intended for utilities, you ground first, then test.
2. Standing energized work permits are even mentioned in the 2012 edition of 70E at least. The key is to ensure that you apply the same amount of scrutiny that you would apply to the energized work permit. I know of several plants in SK that have standing permits specifically just for the 120 V controls, and have implemented a similar one here.
3. If you have remote trip, I don't know what additional risk there would be for remote close as well. Many plants have what is commonly called a "mimic panel" and with todays microprocessor controlled relays, I can even plug in a battery operated wireless dongle into the front of the relay and sit in my truck outside the room and operate the breaker without being anywhere near it. The safety concern here is if you close when it is unexpected, but that's the reason we have something called lock out procedures.
4. Item 5 is incorrect strictly speaking from a safety point of view. The failure rate for disconnects is one to two orders of magnitude lower for disconnects over circuit breakers. The 70E Technical Committee reduced the H/RC value based on the lower likelihood. However this is invalid from the start. The arc flash hazard is not reduced. Wearing under-rated PPE has about the same risk if an arc flash were to occur as wearing no PPE at all. In fact Doan and a couple others have published a paper testing this and found that although PPE worn according to calculations in IEEE 1584 works 100% of the time (so far), there is only a 50% chance of avoiding injury by following the tables with reduced PPE. Thus, the correct H/RC is either "4" or "0", not "2". Better yet, do your own study. But for the purposes of illustration, we can stick with the tables.


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