Services & DistributionQuestion 3 of 521
The only grounding electrode is a concrete-encased electrode (Ufer). What is the largest copper GEC that must be run to it?
a.4 AWG
b.6 AWG
c.2 AWG
d.1/0 AWG
Explanation
Per 250.66(B), where the GEC connects solely to a concrete-encased electrode, it need not be larger than 4 AWG copper. 6 AWG is the cap only for rod/pipe/plate electrodes; 2 AWG and 1/0 exceed the concrete-encased allowance.
Law Reference: 2023 NEC §250.66(B)Practice all 521 questions free — no signup required.
Related questions on this topic
- A 200 A service uses 250 kcmil copper ungrounded service-entrance conductors. Per Table 250.66, what is the minimum copper grounding electrode conductor (GEC)?
- The GEC from a service runs only to a driven ground rod (rod/pipe electrode). What is the largest copper GEC required for this connection?
- A feeder is protected by a 100 A overcurrent device. Per Table 250.122, what is the minimum copper equipment grounding conductor (EGC)?
- What is the minimum copper EGC for a circuit protected by a 200 A breaker, per Table 250.122?
- What is the minimum length that a ground rod electrode must be in contact with the soil?
- A single ground rod is installed. Under what condition is a supplemental electrode NOT required?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against California CSLB C-10 Electrical Trade Examination · How we review