Transformers And Gfci's

[Mainstreet]

I put in a 480v single phase to 120v 5kva transformer to get a couple of outdoor outlets going but the GFCI's will not work at all. I am getting 120v on secondary side and the lights are on. What am I missing?

 

[rlMutch]

How did you ground the secondary (120V side) of the transformer?

 

[don_resqcapt19]

How did you try to test the GFCIs?
Don