Grounding Metal Junction Boxes

[jar546]

This metal junction box does not have a pigtail ground even though there is an equipment ground entering and leaving the box.

Is the lack of a ground a violation?

If it is, what NEC code do you cite, if not, what code allows a metal box to be ungrounded?

 

[bill1952]

Interesting. Looking forward to answers. In this application, no different than a conduit body, which is not grounded.

 

[wwhitney]

The metal box is being grounded by the conduit system in which it is installed. The wire type EGC that is being run is an optional redundant measure.

Since none of the conductors are spliced in the box, there's no requirement to interrupt the wire-type EGC that was installed in order to redundantly ground the box. 2020 NEC 250.148.

Cheers, Wayne

 

[jar546]

If multiple circuits are spliced within the box or terminated to equipment within the box, all the EGCs must be connected together and to the box unless exempted under 250.148. If a metal box is grounded by a metal raceway system and the circuit conductors are not spliced or terminated to equipment in the metal box, the wire-type EGC is not required to be connected to the box. Wire-type EGCs that are not spliced or terminated within a box do not have to be connected to the box; however, the box (if metal) is required to be connected to the EGC of the circuit with the highest rating that is contained in the box.

 

[wwhitney]

If multiple circuits are spliced within the box or terminated to equipment within the box, all the EGCs must be connected together and to the box unless exempted under 250.148.

Right, the wire-type EGCs associated with the circuits whose conductors are spliced. Wire-type EGCs associated only with any circuits that go straight through unspliced do not require connecting to the box. This only becomes relevant when you have multiple redundant wire-type EGCs.

however, the box (if metal) is required to be connected to the EGC of the circuit with the highest rating that is contained in the box.

In the picture, the box is connected to an EGC of the circuit, namely the metal conduit (EMT).

Also, I disagree on the "highest rating" part of your statement. Per 250.148, only the wire-type EGC of the circuits spliced in the box need to be connected to the box. So if the highest rating circuit passes straight through unspliced, its EGC does not need to be connected to the box.

Cheers, Wayne