grounding questions

[Strathead]

Hey everyone. It has been a while. I am out in the field again as a quality manager for a new hospital project, so I don't get to sit at a computer much. Anyway, I have a couple questions that are bugging me.

Actually I will start with how I understood the code, and you can tell me where to find the references or if it is an urban myth. I thought that we could pull a ground through a box if none of the conductors are cut, but if any conductors are cut, the ground must be cut and bonded to the box. I also thought that if we left enough wire to cut and splice in the future, the ground had to be cut and bonded to the box at the time of installation. I think, after searching the code, the last part, at least, is an urban myth. Please if I am correct for any part of this provide me a code reference. Also, where does it state that only one grounding conductor is required in a conduit.

Here is the reason I ask. My EE on the job is claiming to we aren't ok with our installation. We have a gutter above a panel with 5 1 1/4" conduits with multiple #10 wire circuits protected at 20 amps each having a single #10 ground. He says that we don't comply with 517 redundant grounding and that in order to comply we have to pull a grounding conductor sized per 250.122 which he interprets as being sized per the main breaker in the panel.

Please help.

 

[packersparky]

First question. If the EGC is not spliced it is not required to be connected to the box.

250.148 Continuity and Attachment of Equipment Grounding Conductors to Boxes. If circuit conductors are spliced within a box or terminated on equipment within or supported by a box, all equipment grounding conductor(s) associated with any of those circuit conductors shall be connected within the box or to the box with devices suitable for the use in accordance with 250.8 and 250.148(A) through (E).

2nd question. 250.122(C)

(C) Multiple Circuits. Where a single equipment grounding conductor is run with multiple circuits in the same raceway, cable, or cable tray, it shall be sized for the largest overcurrent device protecting conductors in the raceway, cable, or cable tray. Equipment grounding conductors installed in cable trays shall meet the minimum requirements of 392.10(B)(1)(c).

3rd question. The EGC has to be sized per the overcurrent device that is protecting the circuit. If it is a 20 amp circuit, a 12 awg is sufficient. 517.13 (A) requires that the wiring method qualify as an EGC. 517.13(B) requires an insulated EGC be connected to receptacles and metallic boxes, etc.

I think that your installation is compliant.

 

[texie]

I agree with packersparky with one exception. In the 2017 edition (B)(1)(2) was changed to include language that all metal enclosures in the branch circuit need to be connected to the insulated EGC and thus would require that the EGC be connected to the box even if there are no splices or devices.