This electrical schematic details the grounding and bonding configuration for a separately derived AC system transformer. Primary and secondary feeders connect to the high-voltage H1-H3 and low-voltage X0-X3 terminals, with electrostatic ground shielding on each phase. All conductors bond to a single point of connection at the transformer X0 terminal per the manufacturer instructions. The equipment grounding conductor, grounding electrode conductor, and supply-side bonding jumper are sized per National Electrical Code requirements. The grounding electrode connects to the nearest metal water pipe or structural metal grounding electrode in accordance with NEC 250.30 and 250.52.
LEGEND: N - NEUTRAL G - EQUIPMENT GROUND PRIMARY SECONDARY X1 X2 X3 C H1 H2 H3 ELECTROSTATIC GROUND SHIELDING ON EACH PHASE ALL CONDUCTORS TO BOND TO SINGLE POINT OF CONNECTION AT TRANSFORMER X0 TERMINAL PER MANUFACTURER EQUIPMENT GROUNDING CONDUCTOR MINIMUM SIZE PER NEC TABLE 250.122 (COPPER) UNLESS OTHERWISE NOTED X0 GROUNDING ELECTRODE TO METAL WATER PIPE GROUNDING ELECTRODE PER NEC 250.52(A)(1) OR STRUCTURAL METAL GROUNDING ELECTRODE PER NEC 250.52(A)(2) WHICHEVER IS NEAREST IN ACCORDANCE WITH NEC 250.30 GROUNDING ELECTRODE CONDUCTOR MINIMUM SIZE PER NEC TABLE 250.66 (COPPER) UNLESS OTHERWISE NOTED. A COMMON GROUNDING ELECTRODE CONDUCTOR MAY BE UTILIZED FOR MULTIPLE TRANSFORMERS (SEPARATELY DERIVED SYSTEMS) IN THE SAME VICINITY IN ACCORDANCE WITH NEC 250.30 SECONDARY FEEDER NEC 250.30 SEPARATELY DERIVED AC SYSTEM BOND TO CASING SYSTEM BONDING JUMPER B A G N A B C G PRIMARY FEEDER NOTES: 1. REFER TO ELECTRICAL SHEET E7.00 SERIES FOR TRANSFORMER FEEDER CONDUCTORS, EQUIPMENT GROUNDING CONDUCTOR AND GROUNDING ELECTRODE CONDUCTOR SIZES. 2. PER NEC 250.30(5) THE GROUNDING ELECTRODE CONDUCTOR (GEC) CONNECTION SHALL BE MADE AT THE SAME POINT ON THE SEPARATELY DERIVED SYSTEM WHERE THE SYSTEM BONDING JUMPER IS CONNECTED. THIS SHALL BE MADE EITHER AT THE TRANSFORMER X0 POINT OR AT THE NEUTRAL BAR AHEAD OF THE FIRST DISCONNECTING MEANS OR OVERCURRENT DEVICE, BUT NOT BOTH. SUPPLY-SIDE BONDING JUMPER
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