Full Size EGC

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tortuga

tortuga

Code Historian
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Oregon
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Electrical Design
Also other circuits may travel thru the box and have a fault.
The receptacle could get damaged, especially in a metal shop.
 
mbrooke

mbrooke

Batteries Included
Location
United States
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Technician
infinity said:
In the case of the photo in the OP a self grounding receptacle is not required for the 4" square cover that is shown neither is a bonding jumper to the box. The cover is permitted to bond the receptacle to the box. Regarding the bold I would guess that the reason is that if the cover is lose then the box is not properly bonded but without the bonding jumper neither is the receptacle.
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Personally, I would be far less concerned about the box losing the ground than the equipment from a total greater hazard perspective.
 
mbrooke

mbrooke

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Location
United States
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ActionDave said:
I never said it was. And it doesn't change anything about you being wrong about the reliability of green wires as a fault path or the fact that you have little or perhaps no real field experience with any kind of wiring.
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And I just want to address this reply: I can not be wrong because the proof is all around everyone, even you as you type in your room with power.

A wire type EGC is identical in splicing, termination and conductor material as the accompanying phase(s) and neutral. (yes I know about back stabs, not what I have in mind) Out of the billions if not trillions of splices & wire under screw terminations only a small percentage of them burn up or pull open being almost exclusively attributed installer error, misapplication or chronic overload (MWBC on the same phase).

As a result the sub ohm R1+R2+R3+R4 component has been vindicated for over a century.

On the other hand countries or military installations which used TN-C up to the socket outlet receptacle showed considerably more incidences of shock, fire and electrocution with a conduit PEN vs a wire type PEN.

Excessive oxidation, corrosion, loosening, R increase with age ect has lead and still leads to better terminations due the results being immediately noticed: loss of power and joule heating leading to melting and fires. For example, aluminum wire resulted in many high R1+R2+R3+R4 termiantions which resulted in drastic changes in how small gauge AL wiring is made and applied- 8800 series aluminum, CO/ALR devices, copper clad AL, ect ect.

On the other hand the Increase in R with conduit as it ages, along with physical separation, is masked due to the abundant amount of parallel paths and standing neutral to ground faults present in most commercial, industrial and institutional buildings.

The same also applies to the masking of Table 250.122's inadequacy. Wire type EGCs typically do not fuse in these buildings during delayed clearing due to the parellel paths reducing the current carried on the wire type EGC.


Just because the effects happen to be inadvertently mitigated, does not make conduit a trusted EGC. Or that Table 250.122 is good for a 15 second clearing time.

I encourage you to look into ohms law.
 
E

Eddie702

Licensed Electrician
Location
Western Massachusetts
Occupation
Electrician
Don't you have to bond the EGC to the box even if surface mounted? Don't you have to bond around the FMC? FMC is only good for grounding if the fittings are listed and the circuit is 20A or less.
 
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