2

Background and configuration:

I am providing mechanical protection and neatness for a 4ga grounding electrode conductor and a 2nd 4ga auxiliary grounding conductor running from outdoors into (and through) a small weatherproof junction box mounted under my service panel (in exterior-accessible cabinet on garage outside wall).

The box has 3 1/2 inch knockouts, so I would like to use one for an exiting bare ground with intersystem bonding bridge, a 2nd for exit of GEC with Kenny clamp (and Kenny clamp entry to service panel enclosure), leaving the 3rd for entry of both grounding conductors. The GEC will be unbroken but bonded to the auxiliary grounding wire inside the box via a split bolt.

Here's the junction box:

enter image description here

Question

Can I run both 4ga grounding conductors into this junction box inside the same 1/2" pvc flexible liquidtite conduit? I found the following allowed fill table, presumably for current-carrying conductors:

enter image description here

1
  • 2
    Usually it is current heating the wires for fill calculations. Ground wires should not carry current or heat up, so should not be a factor in the fill. Assuming no current carrying wires are added in the conduit , just the grounds.
    – crip659
    Dec 30, 2022 at 2:47

2 Answers 2

2

You're fine on fill

A ½" LFNC-C conduit has 60.4mm2 of usable fill area for 2 wires, and is the worst case for LFNC (LFNC-A and LFNC-B both have slightly more usable fill area), while a 4AWG bare stranded copper wire occupies 21.15mm2 of cross-sectional area, so you still have plenty of room left over after running the 2 4AWG copper wires down the conduit.

1

As the comment states Grounding conductors are not considered to be current caring conductors, so conduit fill is not a factor in this situation. That being said, if you are planning to use any metal boxes or fittings, they must be bonded to the grounding conductors to prevent then from "choking" current flow in the event of a fault. I would suggest using all plastic, nylon or pvc fitting and boxes.

Happy New Year

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.