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 Post subject: Arc flash study- release of digital files
PostPosted: Tue Oct 10, 2017 11:39 am 
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Posts: 142
Do you guys normally release the PTW32 file to the client when the study is completed? Any risk for releasing that document? My concern is that if anyone uses this file without verification and check, it will cause problem. Your inputs will be greatly appreciated!


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 Post subject: Re: Arc flash study- release of digital files
PostPosted: Tue Oct 10, 2017 5:48 pm 
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Location: Rutland, VT
This would depend on what was contractually agreed to. Typically we do not supply the software file.

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 Post subject: Re: Arc flash study- release of digital files
PostPosted: Wed Oct 11, 2017 3:56 am 
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I'm on the Owner's side of things and I require it of our consultants. They generally do so without complaint. We print our own labels so I have to have the files in order to print them in our standard format so our labeling is consistent across campus.

Here is what is in our standard for consultants to adhere to if anyone is interested. This plus all the rest of our standards are referenced in our RFP's and RFQ's so the consultants know what is expected of them going in:

http://cms.bsu.edu/-/media/www/departmentalcontent/facilities/pdf/26%200573%20arc%20flash%20hazard%20analysis%20short%20version.pdf


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 Post subject: Re: Arc flash study- release of digital files
PostPosted: Wed Oct 11, 2017 6:18 am 
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Thanks for the sharing! However, I don't think it is safe to pass the digital file to the others who didn't set up the original parameters in the study, also it may not be valid if the assumption was made by engineer who set up the files and didn't pass to the client completely. Keep in mind that it is for electrical safety program and any little changes could cause big difference in terms of the incident energy level. So, if anything go wrong down the road, whose fault?


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 Post subject: Re: Arc flash study- release of digital files
PostPosted: Wed Oct 11, 2017 7:57 am 
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Noah wrote:
Thanks for the sharing! However, I don't think it is safe to pass the digital file to the others who didn't set up the original parameters in the study, also it may not be valid if the assumption was made by engineer who set up the files and didn't pass to the client completely. Keep in mind that it is for electrical safety program and any little changes could cause big difference in terms of the incident energy level. So, if anything go wrong down the road, whose fault?


I don't change any parameters when I print the labels. I just print them in our format and make sure they match the consultant's reports. I DO however make changes to the model over time when we do adds or changes to the distribution system after the project was initially completed and the consultant is long gone. I will also add that I've gone back to at least one gear manufacturer and a couple of consultants several years after the original study was done and I did not get the model back then when it was originally done and asked for it and they provided it to me with no issues.

I assume you work for a consulting firm. If a co-worker of yours built a model for client and then quit before the job was completely done or say you needed to modify the model a year to two or later would you insist upon re-building the entire model from scratch because it isn't safe due to not knowing everything your co-worker assumed or would you just look over / QC the model first and make the change? I highly doubt you'd start from scratch and I won't either. I DO look at the models closely though and I DO interact with the consultant while they are building the models. They get the primary data from me (available 3 phase and SLG current and X/R and transformer data since I furnish the transformers normally) to start with so I'm not sure what assumptions they'd be making that would not be evident from reviewing the model.

I can see though that many customers wouldn't have SKM or whoever's software or know how to use it and could just pass it on to competitors or misuse the data.


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 Post subject: Re: Arc flash study- release of digital files
PostPosted: Wed Oct 11, 2017 9:42 pm 
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Location: North Carolina
An SKM file on a USB stick can't be stamped. Its an uncontrolled document.

Second why do so many PEs think they have to verify "everything"? That's ridiculous. Do you have SKM source code and verify the calculations it does or do you do some hand calcs and assume the program output is accurate? How do you verify that data on a manufacturer name plate such as 1200 A frame is correct? Did you send it to UL for destructive testing? Did you prove Newtons laws of thermodynamics apply to cable ampacities? Did you send out gear samples to Kinetrics to validate your incident energy estimates and IEEE 1584?

All engineering is done with a huge mountain of givens and assumptions. Part of the job is expressing opinions based on that pile of raw unverified and unverifiable data. When you issue a report and in the process of developing it lots of uncontrolled information changes hands. People make honest mistakes all the time, and some make very dishonest ones. The latter is what you watch out for. If you don't control it as in files you made and control (archive) yourself, its all uncontrolled data provided or handled by others. Once an SKM file leaves your hands it is out in the wild. If it comes back unless it is bit for bit identical it becomes another "provided by others" uncontrolled document. You work with this stuff but be very clear about what is your work which is always a derivative work and never an original from scratch based on first principles design and what is provided by others.

This is very important because as derivative work you are liable for your part. If you design a bridge based on steel specs provided by the steel mill and they provide substandard steel, are you liable for the steel quality if the bridge collapses? What if the construction contractor leaves out 75% of the fasteners or uses undersized beams? Its one thing to hold an engineer liable for their labor...making a calculation error. It is quite another to assume the role of god and be responsible for the fate of the world, a view point that is obviously flawed not only philosophically but legally and practically as well.

If I use an SKM model and state it was provided by the customer (even if I did it) and add new modifications, this is no different than designing a bridge based on performance data provided by a steel mill for specialty grades or the ASI steel book. If the steel quality is substandard and the bridge falls down unless I ran a lab and did testing on it and relied on that performance data, it is derivative and not part of my scope of work. If I were asked to inspect and verify as part of the scope if work, that's an entirely different matter with obviously progressively greater liability and thus cost. Design-build is more risky/rewarding for a reason.


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