Transformer grounding and bonding

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hhsting

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I have Roof Top unit 480V three phase MCA of 200A MOCP 250 has 3#3/0 + 1#4G to RTU. The RTU has integral receptacle 120V single phase and bunch of 120V motor. To power 120V single phase load their is integral to RTU transformer 480V to 120V.

I was wondering if the integral transformer has to apply grounding and bonding rules and need grounding electrode system and grounding electrode conductor 250.30?


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Last edited:
ptonsparky said:
Better yet, there isn’t one disallowing it either.

110.3(B) & (C).
Click to expand...

Typically manufacturer instruction say to follow NEC. 480V to 120V transformer factory install must be grounded no? I was just wondering if manufacturer instruction says nothing or say no then where would the equipment grounding conductor and grounding electrode conductor and grounding electrodes come from?


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Below is from manufacturer instruction of RTU factory installed convenience outlet. I don't see any equipment grounding conductor or grounding electrode conductor. Do you? All it says is ground by the receptacle. I am just wondering what are your thought and opinions?

1585698804217.png
 
The equipment grounding conductor is shown at the top of the receptacle illustration where the white is shown connected to the green yellow. There is no grounding electrode conductor because it's part of a listed piece of equipment, not a stand alone transformer.
 
Ok below is another RTU I used somewhere else whose manufacturer instruction of RTU factory installed convenience outlet. I guess this would require grounding electrode conductor, grounding electrode, system bonding jumper and has equipment grounding conductor: I am just wondering what are your thought and opinions?

1585701485738.png
 
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