“Redundant grounding” 517.13 (B)

[Josuea1990]

Hi.
So, I have a question regarding the so called article “redundant grounding” 517.13 (b). And actually I asked this question to Ryan Jackson himself on his YouTube video titled: Grounding and Bonding in Patient Care Spaces. 2020 NEC 517.13 deep dive. With link:

In the min. 31:27 Ryan says that in order to trip the OCPD we need to decrease the resistance on the EGC by increasing the effective ground fault path.


And in the comments I asked:

@josueayalallanas7142
9 months ago
If the ground fault path is my green 12 awg wire and its resistance is the same as my black hot 12 awg wire since they are the same length and same mass. What difference does it make to parallel the green wire to give it more mass to increase the ground fault current if we are not doing the same to the black wire?
To me, it looks like wanting to decrease the resistance of a long run circuit by increasing the gauge of only 1 wire to compensate for VD in order to get the desired current.
Can anybody see what I mean? 31:27


To what he answered:

@RyanJacksonElectrical
9 months ago
Increasing one conductor DOES decrease the voltage drop...


And then again I asked with a more definitive question:

@josueayalallanas7142
8 days ago
A few days ago I had to increase the circular mils of my EGC based on the size ratio increasement of my hot conductors due to VD, in order to maintain my effective ground fault path. Then I was reminded of this old question I made, and I have not solved yet; about why is that 517 requires the “redundant grounding” to increase the effectiveness of the ground fault path by only increasing the ground fault path, but not the hot conductor’s circular mil as well?Which made me wonder again: ¿why I’m I increasing my green wire if I already increased the hot wire, and as you said: “increasing one conductor DOES decrease VD” ?
Example:
Does this means that;
If for some particular reason I had to increase the size of my hot and neutral of a 15 amp 120 V circuit from 14 awg to 12 awg because of VD and I happen to not have any other white or green size in my van, but I do have a… ¡I don’t know!, maybe a 6 awg black which would be way more than enough and I decide to throw in that 6 awg as a hot, (white and green would still be 12 awg since the ground is never required to larger the the neutral and I’m not allowed to reidentify a black wire as neutral or ground in the field that is 6 or smaller)
¿Would that 6 awg take care of the the VD since I’m increasing significantly more than enough only one conductor?

No answers yet.

Can someone help me understand?

 

[don_resqcapt19]

The following is from an article written by Fred Hartwell and published in EC&M magazine in April of 1994.

Many, particularly-those with an incomplete understanding of the background behind the rule, still argue that wiring methods using multiple equipment grounding conductors should be permitted, since they provide redundancy. The rule originated in the 1987 NEC and was seen by many as an unfair restriction against nonmetallic wiring methods. Accordingly, a serious attempt was made to sidetrack the requirement at the NFPA Annual Meeting.

Those attempts were met by negative arguments from a speaker who had extensively researched hospital grounding performance, particularly in older hospitals that had metal raceways in questionable condition. He found that the mere contact between the conductive surfaces of the raceways and normal building elements resulted in multiple grounding return paths, through concrete reinforcing, plumbing, building steel, and other paths. He found that the total impedance to ground over the raceway often ran between 10 and 50 times lower than the copper grounding conductor; duplicating that copper conductor would only reduce the impedance by a factor of two.

Note that the code never uses the term redundant for the application of 517.13(B).