grounding question

[Designer69]

hey guys check out the attached pic. Its basically creating its own egc path for a panelboard directly to earth.

Would this screw up the effective ground-fault current path? I guess it would... however would it cause dangerous problems ie- non operation of the OCPD??

thanks

see attachment

 

[480sparky]

See the last sentence of 250.4(A)(5).

 

[glene77is]

Check 250.4.a.5, then follow this line of thinking:

The purpose of the EGC is the provide means
for a ground fault to trip the OCPD.

(1) given 120V,
(2) given a ground path (per your drawing)
with 25 ohm (per NEC) back to the OCPD,
(3) given a fault to ground (120V and 25 Ohms),
(4) Result: current flow would be about 5 A, not enough to trip the OCPD.

conclusion: This modification does not work, not even slightly.

Keep the questions coming. Electrical work is safer that way!

 

[Designer69]

Yes totally agree I will keep the questions coming You guys are the best

so can you say that..the path I showed would be higher impedance than should be for a good ground fault current path?

 

[eprice]

so can you say that..the path I showed would be higher impedance than should be for a good ground fault current path?

I believe glene77is has already answered that question.