Voltage drop on ground conductor

[MTG]

We are doing a site lighting job where the engineer has 2#6 conductors and 1#6G originating from a 20A/1P breaker (conductors sized presumably for voltage drop). As the run approaches the last few poles, the current carrying conductors drop to #8 and finally #10, but the ground is #6 throughout the run.

Two questions:
1. Is it necessary to oversize the ground conductor for voltage drop?
2. If the answer above is yes, then why not reduce the size of the ground conductor at the end of the run along with the current carrying conductors?

 

[david luchini]

We are doing a site lighting job where the engineer has 2#6 conductors and 1#6G originating from a 20A/1P breaker (conductors sized presumably for voltage drop). As the run approaches the last few poles, the current carrying conductors drop to #8 and finally #10, but the ground is #6 throughout the run.

Two questions:
1. Is it necessary to oversize the ground conductor for voltage drop?
2. If the answer above is yes, then why not reduce the size of the ground conductor at the end of the run along with the current carrying conductors?

1) If you increase the ungrounded conductor size, you are required to increase the egc size proportionately...250.122(B).

2) You could certainly reduce the egc size where the ungrounded conductors also are reduced. The egc is not required to be larger than the circuit conductors supplying the equipment...250.122(A).