I mean the electrical utility power that connects to the transformer outside of the home or other buildings. i.e. what is the primary winding voltage of the transformer having 220 VAC center-tap secondary?

i have heard as high as 13 kV, but that seems kinda high. isn't it more like 4 kV?

  • \$\begingroup\$ It varies but around here it's 7.2kV. That would be a 12,470 wye. \$\endgroup\$
    – isdi
    Oct 22, 2018 at 17:26
  • 1
    \$\begingroup\$ High enough not to go near it, end of... \$\endgroup\$
    – Solar Mike
    Oct 22, 2018 at 17:29

1 Answer 1


12470V (delta)/7200V (Wye)

13200V (delta)/7620V (Wye)

24940V (delta)/14400V (Wye)

34500V (delta)/19920V (Wye)

source is bulletin 1724-D-114 USDA rural distribution system

  • \$\begingroup\$ i know what Y and Δ is and i know about \$\sqrt{3}\$, but in the expression: "12470Y/7200", what is the 7200? because i would expect the Delta voltage to be \$\sqrt{3}\$ times the Wye voltage. \$\endgroup\$ Oct 22, 2018 at 17:58
  • \$\begingroup\$ I would also expect some 'V' symbols in there. \$\endgroup\$
    – Transistor
    Oct 22, 2018 at 18:10
  • \$\begingroup\$ i think volts is assumed. unless i see "kV" in there. \$\endgroup\$ Oct 22, 2018 at 18:11
  • \$\begingroup\$ You are correct, I believe they/I have a typo in the "Y/"order. Fixing now. \$\endgroup\$
    – isdi
    Oct 22, 2018 at 18:13
  • \$\begingroup\$ Volts is correct, thought about the whole ',' vs '.' nomenclature left unambiguous (though it would be one heck of a wire at 12.47V :-) \$\endgroup\$
    – isdi
    Oct 22, 2018 at 18:17

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