The year 2020 provided me with the unique opportunity and the time to produce a series of videos on topics that you told me were of interest to you. I recorded them from my house, and livestreamed them over the course of several months. There were a lot of you that might not have been able to tune in, and others who did, but would enjoy the chance to see them again. We'll be sending them out monthly in a newsletter series. Enjoy and feel free to share!
This video is about how to properly ground a corner-grounded delta system. So why do we have corner-grounded delta systems? Well for many years electrical systems were ungrounded and these ungrounded systems have inherent overvoltage problems which is the reason we switched to grounded systems that are installed throughout the country today. The easiest way to ground an existing ungrounded delta system is to corner-ground it.
The phase conductor that is grounded must be identified usually white or gray, other options are available in accordance with 200.6.
Be aware this is not a neutral conductor, but the voltage to ground for this corner-grounded phase conductor is zero volts. Overcurrent protection is not required for grounded conductors, however if provided the overcurrent device must open all the circuit conductors simultaneously including the corner-grounded phase conductor in accordance with 240.22.
There is no requirement on what phase to actually ground A, B, or C, so it is up to the installers preference on what phase to install the system bonding jumper and grounding electrode conductor to the grounding electrode that grounds the system.
These corner-grounded delta systems are very rare and have limited applications. Watch this video as I briefly cover “Corner-Grounded Delta Systems” and enjoy this interesting topic!
Click here or on the image to watch the video [3min:56sec].
|
|
|
|
