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Discussion Starter · #1 ·
My company is working at a building were the incoming service is a Delta system. The transformer that is installed is a Delta to Wye. The guys working there have found voltage from the secondary side @ XO to ground. They have megged all the wires through out the system found no problems. The problem has me perplexed I have never come across this before. Any ideas on this. Thanks in advance.
 

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Are you megging after its terminated on the primary side? The b phase won't give a reading because it's grounded. If, of course, it's 3 phase
 

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Bilge Rat
motors and controls.........
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If the secondary of the transformer is a wye, XO is supposed to be bonded to the grounding system. I'd be willing to bet that the bond strap was lifted for the megger test and not replaced.

Note that there can be exactly one XO to ground bond, more than one could result in voltage from XO to ground.
 

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Discussion Starter · #5 ·
I will pass that on to them. Thank you. With All the xformers I have hooked up never came across this so when they called me I kinda sratched my head. Lol
 

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My company is working at a building were the incoming service is a Delta system. The transformer that is installed is a Delta to Wye. The guys working there have found voltage from the secondary side @ XO to ground. They have megged all the wires through out the system found no problems. The problem has me perplexed I have never come across this before. Any ideas on this. Thanks in advance.
What was the voltage from X0 to ground?
 

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67 or 76. Volts
What kinda delta/wye you talking about? Was it a 480/208? Where were the voltage measurements taken? At the transformer? At the panel a few feet away? Anyway, check it with a wiggy. It's probably nothing. There are a few threads on here about "phantom voltage". I would read up. I think this might be what you're experiencing. Just my .02
 
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