How to size the grounding conductor in switchgear?

[zxfabb]

In IEC 61439-1, there is a sub-clause defining a minimum cross-sectional area of protective conductor PE or PEN. My concern is: are there any similar requirements in IEEE/UL standards or NEC? what is the practice in North America? Thank you.

Cross-sectional area of phase conductors mm2	Minimum cross-sectional area of the corresponding protective conductor (PE, PEN) mm2
S < 16	S
16 < S < 35	16
35 < S < 400	S/2
400 < S < 800	200
800 < S	S/4

 

[m sleem]

Table 250.66 showing the grounding electrode conductor GEC form service equipment (generator or transformer or panel) to rod.
Table 250.122 showing the equipment grounding conductor EGC from equipment (other than service equipment) to previous breaker or last breaker.

If i understand you correctly, the connection inside the switchgear between the grounding & grounded conductor (neutral) is MBJ (main bonding jumber) shall be sized in accordance with 250.28(D)(1) through (D)(3).

 

[Sahib]

The OP is talking about the EGC.

 

[zxfabb]

Yeah, I meant EGC. Thanks to you guys.

 

[JoeStillman]

I believe the UL standard for ground bus bars in switchgear is minimum 12.5% of phase conductor cross-sectional area.

 

[Smart $]

Yeah, I meant EGC. Thanks to you guys.

250.122 EGC are sizes based on the overcurrent protection device rating, not circuit conductor sizes.

250.66 for grounding electrode conductors and grounding bonding jumpers. It is based on the size of the ungrounded circuit conductors.