Re: Transformer XO
Ok Roger let have one more go at this. As drawn in your diagram there is no parallel currents paths. If your transformer is setting outside on a pad and the grounding you have indicated is one or two ground rods there would be no parallel paths. In most industrial setting you would have parallel paths. You would have water pipes and the metal frames of the building bonded to the grounding electrodes and thus back to the transformer. You would create multiple parallel current paths from the conduit and EGC that are connected to the electrical equipment. The paths would be created by the conduit and equipment being in contact with the metal parts of the building. I hope this explains where the parallel current paths come from. The bonding as shown in your diagram is allowed by 250.30 (A) (1) Exception No. 1. as long as it doesn?t create a parallel current path and the earth isn?t considered a parallel path. There is no reason to start making nasty little remarks in your post. You might have installed thousands of transformers I don?t know. I have installed two in the last month and I would guess less than one hundred total. But I have never received one with a factory installed bonding strap from the xo connection to the frame of the transformer. Maybe we are installing different types of transformers. The most common one we uses is a 112.5 KVA three phase,dry type.
[ January 10, 2004, 04:41 AM: Message edited by: mclain ]
Ok Roger let have one more go at this. As drawn in your diagram there is no parallel currents paths. If your transformer is setting outside on a pad and the grounding you have indicated is one or two ground rods there would be no parallel paths. In most industrial setting you would have parallel paths. You would have water pipes and the metal frames of the building bonded to the grounding electrodes and thus back to the transformer. You would create multiple parallel current paths from the conduit and EGC that are connected to the electrical equipment. The paths would be created by the conduit and equipment being in contact with the metal parts of the building. I hope this explains where the parallel current paths come from. The bonding as shown in your diagram is allowed by 250.30 (A) (1) Exception No. 1. as long as it doesn?t create a parallel current path and the earth isn?t considered a parallel path. There is no reason to start making nasty little remarks in your post. You might have installed thousands of transformers I don?t know. I have installed two in the last month and I would guess less than one hundred total. But I have never received one with a factory installed bonding strap from the xo connection to the frame of the transformer. Maybe we are installing different types of transformers. The most common one we uses is a 112.5 KVA three phase,dry type.
[ January 10, 2004, 04:41 AM: Message edited by: mclain ]
