Step up transformer install question

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tom baker said:
Is the secondary Wye connected?
If so you are required to have a SBJ to ground
Sorry I answered and didn’t post. I had a 480V motor controller, the control power secondary was not grounded. It was very difficult to TS the control wiring as there was no ground reference
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Not required to be a grounded system unless the neutral is being used as a circuit conductor. If it is not a grounded system, ground detectors will be required.

Yes an ungrounded system can be more difficult to troubleshoot. One of our clients used ungrounded 120 volt control power for their motor controls. The first thing I would do when I had to troubleshoot that system, was to add a temporary grounding connection.
 
don_resqcapt19 said:
Not required to be a grounded system unless the neutral is being used as a circuit conductor. If it is not a grounded system, ground detectors will be required.

Yes an ungrounded system can be more difficult to troubleshoot. One of our clients used ungrounded 120 volt control power for their motor controls. The first thing I would do when I had to troubleshoot that system, was to add a temporary grounding connection.
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I find testing to ground when troubleshooting isn't the right thing to do, especially with non grounded system or even grounded multiwire systems yet many put more emphasis on the "to ground" voltage then they should when something isn't working. If you testing something that is supposed to operate at 240 volts, you can read 120 to ground on both lines but still have an open circuit on one the supply lines. You need to be testing line to line and if you don't have 240 then something is open somewhere. If you find a switch with 240 across it, then it is what is open, whether by intended operation or malfunction, it is still what is the open component in your circuit.
 
kwired said:
I find testing to ground when troubleshooting isn't the right thing to do, especially with non grounded system or even grounded multiwire systems yet many put more emphasis on the "to ground" voltage then they should when something isn't working. If you testing something that is supposed to operate at 240 volts, you can read 120 to ground on both lines but still have an open circuit on one the supply lines. You need to be testing line to line and if you don't have 240 then something is open somewhere. If you find a switch with 240 across it, then it is what is open, whether by intended operation or malfunction, it is still what is the open component in your circuit.
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I can agree for power system troubleshooting, but not for 120 volt control circuit troubleshooting. Often, because the system is not operating, there is more than one open, so you can't read voltage across the control device. I troubleshoot those with a wiggy and test to ground, and as I said for the on client that had ungrounded control power transformers, I would put a temporary ground in the MCC bucket to do the remote troubleshooting.
 
don_resqcapt19 said:
I can agree for power system troubleshooting, but not for 120 volt control circuit troubleshooting. Often, because the system is not operating, there is more than one open, so you can't read voltage across the control device. I troubleshoot those with a wiggy and test to ground, and as I said for the on client that had ungrounded control power transformers, I would put a temporary ground in the MCC bucket to do the remote troubleshooting.
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Ungrounded control circuit at any voltage you need to test to a known working "common" point then.
 
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