250.21(A)(3) and 250.30(A)

[Isaiah]

I have a vendor drawing that shows a 2 wire 2000VA control transformer 480-240V, (H1 and H4 connected to X1 and X4 respectively).
It feeds a small heater on an overhead crane. The secondary side is NOT showing a grounded conductor or a GEC, but the system overall is grounded and the heater shows a connection to plant earth (PE). I’m thinking there needs to be a conductor connected to X2 on the XFMR ran to the heater. Thoughts?


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[Strathead]

So it is an auto transformer?

 

[Isaiah]

So it is an auto transformer?

it’s a two winding control transformer


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[Strathead]

it’s a two winding control transformer


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But when you say (H1 and H4 connected to X1 and X4 respectively), that makes me think the two windings are wired like this, which would mean it is already grounded by the equipment ground.

 

[Isaiah]

But when you say (H1 and H4 connected to X1 and X4 respectively), that makes me think the two windings are wired like this, which would mean it is already grounded by the equipment ground. View attachment 2566635

Sorry for the confusion but this is a two winding additive polarity Control transformer


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[augie47]

IMO, it doesn't meet the criteria of 250.21(A)(3) but it also doesn't meet the requirements in 250.21(B).
Seemingly you would be fine but need to add a detector per 250.21(B)