mandatory grounding conductor

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discusted electrician

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Why does the NEC 2o05 article 250.118 allow metal raceways to be used as an equipment grounding conductor. As gravity and time takes it toll, locknuts, screws on couplings and connectors come loose, thus loosing the ground fault path and defeating the purpose. In a large industrial plant it is not possible to check every little screw or locknut to insure continuity. Why do inspectors allow this practice and the governing board not clearly see this as a safety issue. Using the metal raceway as a sole means of grounding still baffles me. Why are circuits 50v or more to ground not required to have an grounding conductor pulled along side the circuit within the raceway to insure a ground fault path is secure. Or am I missing something in the code book that mandates all ac circuits have a grounding conductor with them?
 
Well, the truth of the matter is, in most instances metallic raceways are better EGC's than a wire is.

Roger
 
And many inspectors do not allow it as their jurisdiction have an ordinance that requires a grounding conductor. I allow it, because it's in the code book.
 
Don't forget, the rules in the NEC are just one step above illegal. Since the NEC is a set of 'minimum' rules, your are free to exceed them anytime your wish. Go ahead and pull in a grounding conductor in every run you do but don't make it a requirement for all of us. :)
 
discusted electrician said:
As gravity and time takes it toll, locknuts, screws on couplings and connectors come loose, thus loosing the ground fault path and defeating the purpose.
Click to expand...

:-?

If this were even remotely true, everything ever built (in the "modern" era) would fall apart....entire buildings would collapse....cars would simply fall apart on the interstate...etc etc etc.


Gravity and time are not the issue...people are mostly likely at fault....from the "git 'r dun" installer to the "gee boss I always wanted to fix a trans-mission" dude to the knuckle head in a fork lift who runs amuck...etc.
 
discusted electrician said:
Why does the NEC 2o05 article 250.118 allow metal raceways to be used as an equipment grounding conductor. As gravity and time takes it toll, locknuts, screws on couplings and connectors come loose, thus loosing the ground fault path and defeating the purpose. In a large industrial plant it is not possible to check every little screw or locknut to insure continuity. Why do inspectors allow this practice and the governing board not clearly see this as a safety issue. Using the metal raceway as a sole means of grounding still baffles me. Why are circuits 50v or more to ground not required to have an grounding conductor pulled along side the circuit within the raceway to insure a ground fault path is secure. Or am I missing something in the code book that mandates all ac circuits have a grounding conductor with them?
Click to expand...

Gravity and time have taken its toll on me and I still consider myself a good enough ground to wear my gloves:D
 
jrannis,

If you do a search in the forum you will find some interesting info. Try searching "Soares" "Raceway as EGC".

Cpal quoted
"If you check the tables in the IAEI adaptation of Soares book on grounding. Tables 11 and 13 suggest that the size of the OCPD and the length and diameter of the raceways; Conduit , and EMT are terminal when employed as an EGC.

For example a run with conductors 12AWG protected at 20A in 1/2 EMT. The maximum length of raceway is indicated as 265 feet."

Good luck

JJ
 
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