Bonding a Transformer that was originally wired with floating Neutral

[StarCat]

I am sorry to have been away from the forum for such an extended period of time. I was partially disabled in 2020, and it changed a major lot for me.
I am coming back to a job that I was on many years ago. It involves a small 480V to 240-120V control transformer on a pump station.
The Master electrician who supervised the job, was mistaken and did not bond the neutral to ground on the secondary side of this transformer, which I contacted him about and told him was a mistake. The people involved who were asked to correct this matter, did not properly understand it and did not make the correction.
There have been a number of changes made to some of the control wiring that this transformer supplies, but its all 120V usage. I am askng myself if there is anything I have failed to consider when I bond the center tap to the subpanel ground bar that could be an issue?
Something is bothering me about this, but I cannot quite nail it down.
Any check list is helpful.

 

[LarryFine]

Welcome back, Kotter.

I would first check for voltage between the neutral and the grounding.

If you measure some, repeat with a low-impedance tester or a 120v bulb in parallel.

 

[infinity]

Welcome back.
Sorry for what happened to you. Glad to hear that you're getting back into it.

Nothing to consider that I can think of, just bond the center tap. What size is the transformer?

 

[ptonsparky]

Is the output of the transformer actually using the center tap or is it strictly 120v output? I don't remember any control transformers wired that way, but my experience is limited.

 

[StarCat]

I am using the term " control transformer " loosely.
I will write down the VA rating next time I am on the job. Its a small step down transformer feeding a 240-120V subpanel backfed on a 2-Pole 20A breaker. The load is strictly 120V, control duty and a couple of light fixtures in the room. I see pretty much exactly 120V potential between the ground and floating neutral. Quite dangerous as regards ground faults to the case conductors in that room.

The real machine loads are all 480V-3PH, on 120V control. There are some relays, a motor starter, and one VFD. Some of the control wiring operates things which are no longer, or will no longer be used, and some of it was done very poorly. There was a Warrick style conductivity control which was removed.
I really hate to make the point, but farm and ranch type installations are some of he most dangerous and compromised I have ever come across. The last one I wrote about on the forum being at an animal resuce in Idaho which was highly dangerous in all respects. I really do not understand the type of people who are nonchalant about exposed live conductors, open distribution panels, and not grounding submersible pump services. But the pattern always seems to repeat. There is always a " clean up " operation that seems to be required in these cases. Damage control, if you will.


Infinity good to hear from you.

 

[infinity]

I am using the term " control transformer " loosely.

I only asked because a true control transformer up to 1000 VA you won't need a GEC.