OSHA CFR 1910.269 Compliance - Arc Flash Assessments

[Herk]

My company is beginning to receive requests from utility companies and co-generators to conduct studies that comply with OSHA's CFR 1910.269 January 1, 2015 deadline for completion of arc flash hazard estimates. Having trouble getting my head around the process and implementation.

For past power system studies we have relied on SKM PTW software. For system voltages <15 kV we selected the IEEE 1584 method. For system voltages >15 kV we selected the NESC 2012 option. However, per CFR 1910.269, Appendix E, "Table 12 - Selecting a Reasonable Incident-Energy Calculation Method" , it appears that ARCPRO software will need to be used to fully determine arc flash incident energies at voltages >15 kV. The ARCPRO software at $2,200 is relatively inexpensive, but I do not believe that it has label production capabilities, is not standalone and it does not interface with power system study programs like SKM PTW.

From what I have been able to ascertain, to conduct a study on systems where voltages are >15 kV:
1. We would model the system in SKM PTW based on the NESC 2012 option and perform all analyses (short circuit, equipment evaluation, coordination and arc flash hazard).
2. Extract relevant data for a given bus from the SKM arc flash hazard analysis report (e.g., SLG Bolted Fault current, Duration of arc, Gap distance, ...), input to ARCPRO and run the program.
3. Copy the SLG Incident Energy analysis result from ARCPRO and paste into the SKM arc flash hazard analysis report overwriting the previously calculated 3-phase incident energy value for the given bus (Note - I have not been successful overwriting, but to compensate I can adjust the 3-Phase Multiplier discussed in the following step).
4. Select the appropriate 3-phase to single-phase conversion factor from CFR 1910.269 (e.g., 1.2x to 2.2x for open-air and 3.7x to 6.5x for enclosed) and enter into the SKM arc flash hazard analysis report 3-phase multiplier column.
5. Repeat steps 2., 3. and 4. for each bus and print labels for equipment operating at >15 kV.

To complete the study at a site (e.g., a substation):
1. We would re-run the study using the IEEE 1584 method before printing labels for equipment operating at <15 kV.
2. Run DC arc flash hazard analysis for equipment operating at >50 Vdc.

Rough process, and I may be completely off base, but if the above steps are anywhere near correct, CFR 1910.269 compliant studies are going to be very labor intensive.

Comments on the outlined process or advice on a simpler approach would be greatly appreciated.

 

[dpc]

EasyPower has the NESC arc-flash equations built into it - it's an option for any buses defined as open air. So you can do all the calculations from a single model. No need for ArcPro.

(Full disclosure - I do some consulting/training work for EasyPower from time to time)

The major distinction is for open air equipment versus enclosed equipment.

 

[Herk]

dpc - Thanks for your comments.

We can apply the NESC 2012 option in SKM and EasyPower; however, there are differences between NESC 2012 and OSHA's 1910.269 Minimum Approach Distances (MAD) and arc flash calculation methods. Since OSHA will only accept ARCPRO results for arc flash hazard estimates on systems operating at >15 kV (that is spelled out in 1910.269, App E, Table 12 linked in my original post), ARCPRO must be used to achieve OSHA compliance. Also, I have read that some utility companies dictate the use of ARCPRO, so there must be a viable means to combine a program like EasyPower with ARCPRO.

We are trying to find out how others are proceeding. Perhaps I'm over-analyzing, but the issue comes down to differences between NESC and OSHA requirements and the disconnect this creates between software packages.

The process that I outlined was loosely based on a discussion with SKM, but I hit a wall when I tried to get an answer from EasyPower. I'll have another run at it with both companies and unless someone in this forum is able to offer a recommended solution, I'll report here if/when resolved.

 

[dpc]

I haven't check SKM regarding the NESC equations, but in EasyPower you can specify what working distance to use for any bus. The calculated results should match ArcPro, assuming the same inputs are used. We have ArcPro and you are not going to integrate that with anything else, IMO. I certainly wouldn't buy ArcPro based on some table in the OSHA regs if you can get the same results in another software package.

Arc flash calculations are not an exact science.