What to ground

[jdschwartz89]

What all has to be grounded at the first means of disconnect from a seperatly derived system?

for instance if I have 480v going to a dry type XFMR stepping down to 120/208v and going into a my first panel, and We're running EMT from XFMR to panel. do i just have to have a bond bushing on the main feed or on every conduit entering the panel? also does the main feed have to have bond bushings on both ends (XFMR&Panel) or just the panel end?

 

[ActionDave]

It depends on whether you bond the XO in the transformer or the first disconnect. That is where you bring your Grounding Electrode Conductor, usually a tag to the building steel. 250.30 lays it out pretty good and will help explain about Supply Side Bonding Jumpers sizes and EGC's better than I can. If you have access to a handbook there are some good illustrations. No need for any fancy bushings.

 

[augie47]

Between your transformer and you 208/120 secondary panel you need your phase condcutors, your grounded conductor and your bonding jumper. Your EMT, if properly installed can serve as your bonding jumper.

 

[infinity]

Bonding bushings are not required for the primary or secondary conductors in a transformer if you have full size KO's. If you have concentric or eccentric KO's on the primary (over 250 volts to ground) then you would need one on that raceway.

 

[electricalist]