Vehicle Chargers

[patpappas]

While installing three 240 volt EVR40 charging stations we stepped 480 1PH down to 240 1PH, connected the chargers to 240 v with a ground wire as per manufacturers specs, when energized we received a fault condition, Tech support called it a grounding issue, tried different ways to improve the grounding issue non proved good, requiring only 240 volt and no neutral we had not bonded the XFMR center tap so we tried that just for kicks and the chargers were happy, no fault, I do not understand why, like I said 240 volt (or 208) and a ground field connections only. No diagram I seen anywhere 480/240 1PH shows the X2-X3 bonded just for 240 volt. Thank you. (This is give'n me a headache)

 

[texie]

While installing three 240 volt EVR40 charging stations we stepped 480 1PH down to 240 1PH, connected the chargers to 240 v with a ground wire as per manufacturers specs, when energized we received a fault condition, Tech support called it a grounding issue, tried different ways to improve the grounding issue non proved good, requiring only 240 volt and no neutral we had not bonded the XFMR center tap so we tried that just for kicks and the chargers were happy, no fault, I do not understand why, like I said 240 volt (or 208) and a ground field connections only. No diagram I seen anywhere 480/240 1PH shows the X2-X3 bonded just for 240 volt. Thank you. (This is give'n me a headache)

The transformer you describe is required to be installed as a grounded system per 250.20(B)(1). This would include meeting all the requirements for grounding and bonding in Art. 250 for a separately derived system. Also you will need to meet all other requirements such as disconnecting means, primary and secondary OCP, etc.
You're just lucky that your load equipment had enough smarts in in it to recognize an improper and unsafe installation.