burial depth gfci protected 20 amp branch to shed

[Srv52761]

Confused…
Given: 20 A branch circuit to shed 75’ away.
Tapped from the load side of a gfci receptacle on the side of the house.
Thwn conductors in pvc conduit.

I contend since conductors are gfci protected it can be buried at 12” using 300.5 column 4.
Was told since in conduit I have to use column 3, so 18” depth.
Seems there is already additional protection to the 12” guideline, why do I need the added depth?

 

[infinity]

GFCI protected and 20 amps or less the burial depth is 12".

 

[petersonra]

I don't like the idea of coming off a gfci receptacle though. But it might be the cheapest answer.

If you put it in rigid conduit it only has to be 6 inches deep and no GFCI requirement.

 

[tortuga]

I contend since conductors are gfci protected it can be buried at 12” using 300.5 column 4.
Was told since in conduit I have to use column 3, so 18” depth.
Seems there is already additional protection to the 12” guideline, why do I need the added depth?

You dont tell that person to look at note#4 under table 300.5