Trailer construction

[hhsting]

I have 480/277V main service switchboard on concrete pad outside whose feeder breaker feeds panelboard HV 122 feet away.

The panel HV feeds transformer and Panel LV 208/120V three phase all mounted on steel frame outside

The panel LV has one feeder breaker 90A that feeds disconnect located outside of the trailer. The distance from LV to trailer disco is 18 feet. The distance from trailer to trailer disco is less than 30 feet away.

Questions:
1. Would steel frame which has HV, LV, xfmr considered structure NEC 2017 section 100?

2. Would panel HV need grounding electrode system since it is fed by outside feeder per NEC 2017 section 250.32?

3. Would the Trailer disconnect require grounding electrode system per NEC 2017 section 550.32(A) and250.32 or since panel LV is so close its not needed?

 

[qcroanoke]

Question #1. That sounds like what is called an H frame. You see them on cell sites. They are considered a structure. IMO

 

[hhsting]

Question #1. That sounds like what is called an H frame. You see them on cell sites. They are considered a structure. IMO

And if the panel HV is on wooden pole and panelboard LV on wooden pol, transformer floor mounted?

 

[augie47]

I agree with qcroanoke and, IMO, the answer is "NO' to all 3 questions.