Grounding, High Impedance [250.36, 2020 NEC]

250.36 Grounding, High Impedance - www.MikeHolt.c....
Did you know a high-impedance grounded ac system cannot serve line to neutral loads? In this video, Mike and the team as they discuss NEC Section 250.36 and explain what a high-impedance grounded system is and how it differs from a conventional solidly grounded electrical system
This video is extracted from Mike Holt's 2020 Bonding and Grounding Textbook and Video program. For more information about this product, visit www.MikeHolt.c... or call 888.632.2633.
For almost 50 years, Mike Holt Enterprises has been providing quality electrical Code training to help electrical professionals learn the Code, prepare for exams, and improve their electrical knowledge. Visit www.MikeHolt.com for exam preparation tips and training, instructor and curriculum support, continuing education options, free videos and graphics, and so much more.

[@BOYSWILLBEBOYS2010]

Yes, HRG’s have a huge advantage providing the system is operating correctly. Do you have a video that explains the cons of an HRG? Such as resistor failure, case grounds failure, monitoring system failures.

[@that1electrician]

I never understood why would you want to have a high impedance to ground. Common sense dictates you want a low resistance path to ground in case of ground fault, that way most current going to ground instead of someone touching equipment. So the high impedance grounding is just to limit the current going through the ground fault loop when a ground fault occurs? Is that correct?

[@MikeHoltNEC]

Please watch the video again, it explains the purpose of a high-impedance system. It's the best grounded system of all systems.

[@veeno7650]

In this situation would we still follow table 250.102(C)(1) for sizing the EGC even though the fault current will be approximately 1 amp?

[@MikeHoltNEC]

No, it's sized per 250.36(B).

[@veeno7650]

@@MikeHoltNEC and if the system is above 1000V, we would use 250.187 correct? This section just mentions the cable to be rated for the neutral voltage. Would the EGC still be rated for the maximum current rating of the grounding impedance?

[@MikeHoltNEC]

@@veeno7650 For systems under 1,000V read 250.36(B) 2nd paragraph on conductor size. For system over 1,000V follow 250.187.

[@veeno7650]

@@MikeHoltNEC but 250.187 doesn't mention the current rating of the ground conductor?

[@MikeHoltNEC]

@@veeno7650 Correct, it is what it is.