24 vac grounding one leg question with a 480 vac primary

[RICHARD ROSEBROCK]

i am not sure i am doing this correctly, my first time here.
i know artical 250.20, A says that ac systems of less than 50 volts shall be grounded under the following condition, if the transformer supply exceeds 150 volts.
i just want to make sure i am understanding this statement correctly.
if i am installing a 480 vac to 24 vac transformer in a roof top unit to supply 24 vac to a controller, for the contol system, like trane or johnson controls. this means that i have to ground one leg of the 24 vac side to ground?
someone brought this up today and i just want to make sure that i understand this correctly, and i know this has to have overcurrent protection, i just want to make sure i have too ground one leg of the 24 vac. i know it isn't done alot of the time.

please feel free to email an answer also, i will get it on my phone, i would greatly appreciate it! (because i may not be able to find the answers, new at this)

Thanks
Richard Rosebrock

 

[roger]

Richard, there is no need to ask for an email reply, your question will be better addresssed in a thread.


Welcome to the forum


Roger

 

[don_resqcapt19]

Yes, one side of the 24 volt system must be grounded. I have seen that many times with the control transformer supplied by the unit manufacturer when the supply voltage to the unit was 480.

 

[RICHARD ROSEBROCK]

THANK YOU MODERATOR, MY FIRST TIME POSTING, THIS IS A GREAT SITE,
I WILL KEEP COMING BACK AND CHECKING THE REPLYS
TO BE HONEST, I DO NOT THINK MUST PEOPLE ARE AWARE OF THIS REQUIRMENT TO GROUND ONE LEG OF THE 24 VAC IF THE PRIMARY IS SUPPLIED BY OVER 150 VOLTS.
I JUST WANTED TO MAKE SURE I WAS CORRECT IN MY UNDERSTANDING OF THIS CODE REQUIRMENT.

 

[ritelec]

Yes, one side of the 24 volt system must be grounded. I have seen that many times with the control transformer supplied by the unit manufacturer when the supply voltage to the unit was 480.

and the 24v side was not grounded.