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| Infeasible or Inconvenient https://brainfiller.com/arcflashforum/viewtopic.php?f=33&t=4352 |
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| Author: | Jim Phillips (brainfiller) [ Sun Apr 30, 2017 7:56 am ] |
| Post subject: | Infeasible or Inconvenient |
This week’s question was submitted by one of our forum members and is about infeasible vs inconvenient – a topic that is always good for stirring up a lively discussion. As an example: - A 208 V or 480 V panelboard needs to have wiring added or a circuit breaker added or removed. - The incident energy is less than 1.2 calories per square centimeter. - The panel supplies control power to an assembly line of robots and/or computers. - IF it is shutdown, many hours of production are lost due to robot programming issues. Here is this week’s question (the forum limits the survey question to 100 characters so it is a bit abbreviated) Is deenergizing a panel that feeds robots/computers for production and needs hours to restart: Infeasible Inconvenient It Depends |
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| Author: | bubba [ Mon May 01, 2017 6:43 am ] |
| Post subject: | Re: Infeasible or Inconvenient |
I say infeasible. Making a continuous process industry shut down is of course feasible but if they can not stay in business than it is not practical. |
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| Author: | richranft [ Mon May 01, 2017 7:34 am ] |
| Post subject: | Re: Infeasible or Inconvenient |
It depends. If the facility runs 24/7/365 with no planned shutdowns, I would say it’s “infeasible”. If there are planned shutdowns, and/or there is another source that could feed the new loads but is farther way or is a more expensive option, then it is “inconvenient”. I have seen too many people use the ”continuous process/business interruption” justification to do energized work when in fact there is often a work around that just requires a little more planning and maybe a few more dollars. |
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| Author: | Robertefuhr [ Mon May 01, 2017 8:49 am ] |
| Post subject: | Re: Infeasible or Inconvenient |
I definitely say that this is "Inconvenient" since there was not additional risk that would occur by deenergizing the panelboard. |
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| Author: | JKlessig [ Mon May 01, 2017 9:07 am ] |
| Post subject: | Re: Infeasible or Inconvenient |
I look at it this way. What have they done to prevent other, similar, foreseeable events? Events such as momentary power outages. If "they" have made provision for this process to ride through a brief power outage, then they have a good argument for "infeasible". OTOH if they just "take the hit" for a momentary power outage, then it is just "inconvenient". We have one client, a glass plant who "can not possibly do a planned outage", because they then have to cool the tank and chip out all the glass, and restart. Which they say costs $$$$. But they face the same problem from any thing longer than a few seconds of power loss. Utility problems are a fairly rare event for them, but I would say it is inconvenient, not infeasible. |
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| Author: | stevenal [ Mon May 01, 2017 10:59 am ] |
| Post subject: | Re: Infeasible or Inconvenient |
Inconvenient. Suggest that changes be looked into so that less production is lost next time. The 70E handbook has a good discussion on inconvenient vs. infeasible. |
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| Author: | Voltrael [ Mon May 01, 2017 11:27 am ] |
| Post subject: | Re: Infeasible or Inconvenient |
I've spent most of my career working in 24/7 facilities. You always want to avoid shutting lines down that otherwise never get shut down, but you generally can't justify creating a dangerous situation just to keep production going. |
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| Author: | MargaretE [ Mon May 01, 2017 11:59 am ] |
| Post subject: | Re: Infeasible or Inconvenient |
It depends......If a UPS or emergency generator is supporting the line/each line, I would be more prone to buy in that an interruption might be classified infeasible. If infeasible, I'd work towards performing the work during annual/semi annual maintenance or as part of an overall "outage" schedule. Otherwise, the outage is a costly, time consuming inconvenience. Some threat to life and property should exist if the work has to be performed hot ASAP. |
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| Author: | bbaumer [ Mon May 01, 2017 12:52 pm ] |
| Post subject: | Re: Infeasible or Inconvenient |
The incident energy is less than 1.2 cal/cm^2 Not worth arguing about. Put on your PPE and install the breaker. |
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| Author: | sidlangford [ Mon May 01, 2017 2:11 pm ] |
| Post subject: | Re: Infeasible or Inconvenient |
I would say it is inconvenient - it is poor planning to have such a critical operation with out some type of redundant power source or battery back up - the breaker is defective and should be changed out. if you pitch an installation of a small UPS (Control Power should be a small UPS) with the mention that this should help eliminate future problems it might be an easier sale. |
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| Author: | PaulEngr [ Tue May 02, 2017 12:11 pm ] |
| Post subject: | Re: Infeasible or Inconvenient |
It is inconvenient. I've heard the "continuous process industry" excuse WAY too many times. OSHA has explained their stance on this quite well: https://www.osha.gov/pls/oshaweb/owadis ... p_id=25559 "It appears that your panel is not part of a "continuous industrial process." The term "continuous industrial process" was derived from its use in the National Electrical Code (NEC). In the NEC "continuous industrial process" is used in the context of situations where the orderly shut down of integrated processes and equipment would introduce additional or increased hazards.1 Therefore, to qualify for the exception found in Note 2 of §1910.333(a)(1), the employer must, on a case-by-case basis, determine if the orderly shutdown of the related equipment (including the panel) and processes would introduce additional or increased hazards. If so, then the employer may perform the work using the electrical safe work practices found in §§1910.331-1910.335, including, but not limited to, insulated tools, shields, barrier, and personal protective equipment. If the orderly shutdown of the related equipment and processes would not introduce additional or increased hazards, but merely alter or interrupt production, then the de-energization of the equipment would be considered feasible, and the exception found in Note 2 of §1910.333(a)(1) would not apply. Based on the limited information you provided, it does not appear that de-energization of the panel in question would introduce additional or increased hazards." In other words, this is just a fine print note, not conferring anything additional. Infeasible examples would be for instance taking voltage or current readings...you can't take a reading without being energized. It probably would be a better example for instance in a kiln operation where shutdown and restarting takes about a week along with a tremendous amount of additional work and all the inherent potential hazards that can occur with the shutdown and restarting. OSHA does give "lighting" as another reason for infeasibility but in my mind as a former underground miner, that's a joke. I always have a flashlight on me even today when I no longer work underground. So essentially the phrase "continuous industrial process" should probably be deleted as it doesn't add value to the understanding of the EEWP requirement. |
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