XO to Building Steel

[naplespete57]

Is it always required to tie the XO terminal in a Transformer to building steel or is it simply common practice?

 

[augie47]

There are a few exceptions (See 250.30) but many transformers require a grounding electrode on the secondary. Building steel often meets the requirement.

 

[petersonra]

There are a few exceptions (See 250.30) but many transformers require a grounding electrode on the secondary. Building steel often meets the requirement.

And is often the simplest solution but keep in mind the building steel is not the GE. It is the bonding conductor to the GE. So the building steel has to be bonded to a qualified GE.

 

[don_resqcapt19]

And is often the simplest solution but keep in mind the building steel is not the GE. It is the bonding conductor to the GE. So the building steel has to be bonded to a qualified GE.

Even if the steel is not bonded to a qualified grounding electrode, 250.140(D)(2) will require the grounded conductor of a separately derived system to be bonded to the steel.

 

[Jpflex]

There are a few exceptions (See 250.30) but many transformers require a grounding electrode on the secondary. Building steel often meets the requirement.

This subject is what I also had a question on. According to NEC every building or structure supplied by a feeder except multi wire branch circuit exception must connect to a grounding electrode system

However does this grounding electrode conductor terminate to the feeders first point of disconnect such as the first sub panel for a shed (also provided primary protection of a downstream step down transformer or

Does the grounding electrode and conductor terminate at the sheds downstream 120/240 v transformer XO and ground terminal or, the neutral buss within the second mini sub breaker panel after the transformer (second breaker panel for the transformers secondary winding and conductor protection)?

 

[augie47]

You would need to meet both requirements. You can use the same grounding electrode system for the feeder and the transformer secondary.
It's no different from your having a service to a large building with a SDS transformer inside.

 

[Jpflex]

You would need to meet both requirements. You can use the same grounding electrode system for the feeder and the transformer secondary.
It's no different from your having a service to a large building with a SDS transformer inside.

Boss tripped out today not because the electrical system wasn’t working (which it was) but because the EMT and round box was supported to the metal shed roof.

Without checking the book I believe the NEC code requires EMT to be supported and secured within every 10 feet and every 3 feet of termination such as to the round box to the heat lamp as pictured

My boss said the holes in the roof would allow water to enter the cabinet although the self tappers I used had rubber seals and were listed as water tight

He made me disconnect the EMT run and caulk the holes

Do you think my approach was ok?

 

[LarryFine]

Not really. I would have used a construction adhesive before drilling holes through a roof.

Those washers will only seal between surfaces they touch, like the box and the screw head.

 

[don_resqcapt19]

Have always wanted to try something like these magnetic supports, but never have. Not likely cost effective for this project.

 

[david]

I do not see any roof decking screws in the picture you provided. Not sure how you would suport your conduit and box keeping two inch clearance from the decking for the roof. perhaps mounting uni-strut tothe decking first