If the customer just wants arc flash labels for electrical panels and switchboards only. What data do you need to get on the panels and switchboards? Do you still trace it all the way to the equipment? I’ve seen some reports that just end at the panels. What do you guys normally do?

I rarely did more work than the customer was willing to pay for.
But I always tried to get all of the source data required. For example, I would get motor nameplate data even though the customer did not plan to put a label on the local disconnect.

NFPA 70E & NFPA 70 tell you what has to be labeled, and OSHA refers to these standards. When we do a study, we try and track down all 3-pole circuits and include what they feed in the study.

NFPA 70E 130.5(H) - Electrical equipment such as switchboards, panelboards, industrial control panels, meter socket enclosures, and MCC's that are in other than dwelling units and that are likely to require examination, adjustment, servicing (troubleshooting) or maintenance while energized shall be marked with a label etc.

NFPA 70 (NEC) - 110.16 - Arc-Flash Hazard Warning.
(A) General. Electrical equipment, such as switchboards, switchgear, panelboards, industrial control panels, meter socket enclosures, and motor control centers, that is in other than dwelling units, and is likely to require examination, adjustment, servicing, or maintenance while energized, shall be field or factory marked to warn qualified persons of potential electric arc flash hazards. The marking shall meet the requirements in 110.21(B) and shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.

Unless the customer has requested it, I don't include all 3 phase loads in the model. I exclude them if there is nothing about that feeder that needs to be labeled or doesn't have significant fault contribution. Examples could include commercial kitchen equipment, or small 3 phase exhaust fans or an in-duct electric heating coil or electric water heater etc. when the customer says they don't label disconnects and their electrical safety program says live work on anything not labeled is strictly prohibited.

Yes, if a circuit feeds duct heaters, receptacles etc. we simply put a text block on the drawing stating that and no label is printed, but we do the due diligence during data collection to confirm that. Now granted most field disconnects will come up less than 1.2 cal however if someone will need to verify absence of voltage at a 480-volt RTU for example, they still need to understand the hazard to do that whether doing live work or not. I have had instances where a long cable run will drop the arcing fault current and it can be greater than 1.2 cal so for that reason we try and document as much field equipment as possible.

I don't want to get too far off topic but RE: packaged RTUs, I don't think you can accurately calculate the incident energy on many of those. They often have a molded case switch built into the unit in the panel next to the door or access panel or have a door panel type disconnect in the access door. When you open the access door the control section is pretty much an industrial control panel with relays, contactors, terminal blocks, fuse blocks, control transformer etc. with multiple conductor sizes and bus gaps and voltages. All you can do is calc to the line side of the MCS or disconnect and put a disclaimer in the report. That line side value might be way too low. See my YouTube video on industrial control panels. I think the actual potential incident energy in that case is incalculable. Too many variables.

Most of these prepackaged RTUs have all of the compressors and motors listed on the outside. It's a PITA, but I've typically added these loads up and used the sum for the calculations, since the motor loads tend to be the lion's share of the contribution. Would you say that's an inaccurate way of trying to capture the potential there?

Thanks for taking the time to reply. I understand that, my point was about calculating incident energy, not motor fault contribution. I do the same as you, I model them as one motor. There are so many parts in there (contactors, starters, relays, terminal blocks, different size wires, varying bus gaps etc) that, in my opinion, you cannot accurately calculate incident energy for something like that if you needed or wanted to label the unit. I don't see them as different than an industrial control panel.

How do you possibly produce an accurate arc flash label for disconnect switches and especially custom control panels?!
What is the busbar gap of a disconnect switch with phase barriers? And various CB lug spacing depending on frame size?
What is the busbar gap of a main CB in a control panel?
You certainly can't go past the immediate CB line or load side lugs.
Were these included in the thousands of tests to develop the standard?
Is everyone just using the standard 25mm?
We have been reluctant to produce labels for disconnects, transormers and control panels.
Thanks

I think a lot of testing was done using disconnects or disconnect sized and shaped enclosures so I don't worry much about the calcs with those.

I feel the same as you about industrial control panels. I have starting using the category method for those in instances where the software tells me IE is very low. Here are a couple vids I made on those:

https://youtu.be/D2TL5SpUzXI?si=OuGvnBN28az7r6iK

https://youtu.be/X3-uxvkBqkM?si=VsiHUu3MeC6ihAMh

RE: Transformers, I don't label dry types. I will label pad mounts if the customer insists based on the NESC because the software math isn't reality. Here is a video I made on those:

https://youtu.be/jKqy9uMfwq4?si=oYtk9_o_x6pGoYnw

Brent,

A few comments on your padmount video.

One of the transformers in the video indicates it has a 12470GY/7200 primary, but you've modelled all delta primaries.

You point out the Bay-O-Net primary fuses, yet the model apparently left them out.

Good catch on the Wye-Wye. Mistake on my part.

RE: the fuses, I used to include those when modeling and sometimes depending on the fuse type and transformer %Z it would result in somewhat low IE at the secondary line side of the main. I didn't feel good about that since those fuses are hard to get to blow with arcing faults in my experience after seeing it happen a couple times. Once when I was standing only a few feet away when energizing a new pad mount for the first time.. I quit including them in the model for that reason. I then changed my mind and started including them again but I now fail them so they don't affect the secondary IE results.

Brent, I might have missed the explanation, but why did you privatize your YouTube videos? I'm happy for you that you've retired. That said, those videos remain extremely valuable to those still learning how to do better studies. I hope you decide to make them available at some point.

Couple reasons. First, I don't want to field so many calls and emails asking for help with other peoples studies anymore now that I am "out of the game" and will be transferring my SKM license to one of my customers soon. When that happens I won't have the ability to look at other people's models or test things in SKM in the near future.

I enjoyed helping those folks for the most part to the extent I could although there were a few bad eggs, only a few, looking for me to do their work for them or stamp their work because they weren't licensed even though that is unethical at best and flat out illegal in most if not all states I'm licensed in, or that took advantage of me by calling and texting me dozens of times without putting forth much of an effort to figure it out for themselves first. That got old.

Second, although I often stated in my videos to "do your own research" or "try this yourself" or "just my opinion, which is not necessarily accurate or correct" I still felt like I should add a disclaimer to all my videos to use the content at your own risk and assume nothing I say or demonstrate is accurate. I spent a fair amount of time trying to figure that out but found that was not simple to do so I made all the videos private.

That said, I have had a handful of people ask me for access to the vids which I have granted after they acknowledged use of the videos is at their own risk. If you have a gmail account I can add you to the "permissions list" if you like. Just email me at brent@baumerengineering.com.