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 Post subject: Ethical Question
PostPosted: Thu Aug 29, 2019 7:41 am 
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Joined: Wed May 07, 2008 5:00 pm
Posts: 822
Location: Rutland, VT
Here is a situation:
An arc flash study was performed recently for a system in which there are 2 owners. Owner A owns the main service panel, sub panels and a control panel that feeds sub panels in the field. Owner B owns only the sub panels in the field which consists of a small control panel for a 1/2hp sump pump.

Owner A had an arc flash study done without Owner B knowing about it. Owner B had an internal safety audit done and the arc flash on the small panels was questioned as at the time there was no label on the equipment. I was hired to do an arc flash study for Owner B on their equipment only and during the site visit, it was discovered that there is now an arc flash on the equipment. This was installed between the time of safety audit and my site visit. Owner B then requested that I review the study done by Owner A and still do my own study for Owner B's equipment.

Since I have to model a portion of Owner A's electrical system to get to the equipment owned by Owner B, I reviewed Owner A's report and verified the service information with the utility.

The issue is that the consultant for Owner A used the utilities chart of fault currents for designing low voltage equipment. The main service has a 400A main breaker at 480Y/277V. Per the utility chart the short circuit value is 20kA.

However, the utility service is a pole mounted bank of 3x25kVA transformers and the billing shows a peak load of 28kW. This would be a infinite bus fault current of between 4.5-5.6kA for 2% and 1.6% impedances.

Obviously this makes a huge difference on incident energy values. For example: The main service panel is labeled as 75.9 cal/cm2 whereas it is more likely around 15-16 cal/cm2 with a 2 sec cutoff. Equipment was also noted as overdutied with this 20kA value being used which is not the case.

I intend to pass on my concerns to Owner B which I believe is the only obligation I have and let Owner B tell Owner A. Or should I also follow up with Owner A's consultant?

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Barry Donovan, P.E.
www.workplacesafetysolutions.com


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 Post subject: Re: Ethical Question
PostPosted: Thu Aug 29, 2019 8:28 am 
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Joined: Tue Jan 13, 2009 5:00 pm
Posts: 532
https://www.nspe.org/sites/default/files/resources/pdfs/Ethics/CodeofEthics/NSPECodeofEthicsforEngineers.pdf

See article II.1 in general, and II.1.f. in particular.


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 Post subject: Re: Ethical Question
PostPosted: Wed Sep 11, 2019 10:33 am 
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Joined: Mon Jun 11, 2018 12:02 pm
Posts: 9
Location: Slave Lake, Alberta
Your situation presents many conflicting issues, so going back to the Fundamental Canons of the Code of Ethics, your number 1 obligation is the safety, health and welfare of the public. If you suspect that another member of the profession may have made an error, number 6 would imply that you also have an obligation to confirm the issue first and foremost by discussing the situation with them. If they have made an honest error, the matter can be resolved very quickly. Otherwise, if the situation is still not resolved, proceed from there accordingly by holding number 1 as your prime obligation. This does not constitute professional advise and is just my personal opinion based on past experience that although professionals may be embarrassed by even the tiniest mistake, they would prefer the opportunity to correct that mistake before any harm occurs.


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 Post subject: Re: Ethical Question
PostPosted: Wed Sep 18, 2019 5:59 am 

Joined: Wed Sep 18, 2019 5:51 am
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If I'm understanding the OP correctly, the initial arc flash Study by another company/for another client used table values which were needlessly high as table values always are (assumes worst case scenario). Since the posted arc flash potential energy greatly exceeds the actual arc flash potential this is not a safety issue. To that end it doesn't seem like an ethical obligation to inform them of the actual value as no unknown danger is posed.

You may want to approach them and inform them you suspect the posted information is needlessly high based on table values. Offer you can perform a study and provide more accurate labels at a discounted rate as you already have some of the information needed/modeled.


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 Post subject: Re: Ethical Question
PostPosted: Wed Sep 18, 2019 8:47 am 
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Joined: Tue Jan 13, 2009 5:00 pm
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x704 wrote:
If I'm understanding the OP correctly, the initial arc flash Study by another company/for another client used table values which were needlessly high as table values always are (assumes worst case scenario).


The worst case is generally at lower fault current levels where clearing time is longer. Worst case for equipment is not the same as worst case for IE. A safety concern and ethical obligation exists.


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 Post subject: Re: Ethical Question
PostPosted: Wed Sep 18, 2019 9:56 am 
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Joined: Wed May 07, 2008 5:00 pm
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Location: Rutland, VT
I passed the utility info to the consulting engineering firm and they responded with a thank you. Whether they do anything is unknown. Since I had access to the report, for curiosity, I redid the portions that were outside of my area of responsibility. Since the transformers were a bank of 3x25kVA, 10.5kA primary available fault current and 10k fuses, I got 1.2 cal/cm2. A far cry from the 75.9 cal/cm2 that the consultant had labeled the panel with.

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Barry Donovan, P.E.
www.workplacesafetysolutions.com


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 Post subject: Re: Ethical Question
PostPosted: Mon Sep 23, 2019 5:40 am 

Joined: Mon Apr 06, 2015 9:51 am
Posts: 5
I wonder if the utility is based on an install of 3-100kVA to provide a 400 ampere service, since these would provide 360 amperes continuously. If the transformers were this size, the 20k would be pretty close. I know some utilities if the Maximum available fault current changes because of an utility equipment changeout it is the utility responsibility to upgrade the customer equipment. So the utility states the worst case AIC for that size service.

Is the work the other consultant result in an unsafe condition? This would be the major concern in notifying the others involved. They have overstated the hazard, the other customer may waste money in wearing extra PPE or upgrading the maximum AIC at this time.

The concern I would have if I stated to customer B, you only need 10k equipment, and customer A needs change, and the utility upgrades the transformers, increasing the AIC to the point customer B AIC increase and the utility says it is not their problem, you wont look so good.


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