Randy Dawson here with a head-scratcher from Duke Energy Carolinas. Working on a manufacturing facility audit and the demand charges don't match what I'm calculating from their Rate Schedule LGS. Bill shows $2,847 demand charge for 247kW peak, but tariff shows $11.86/kW which should be $2,929. Customer swears they haven't changed rate schedules recently. The meter data shows clean 247kW peak in July, no power factor issues. Anyone seen Duke apply demand charge adjustments or ratchets that aren't obvious in the standard tariff language?
Demand charge calculation mystery - Duke Energy Carolinas
Ed C. from Nashville. I don't work Duke territory but that math definitely doesn't add up. Are you sure you're looking at the right effective date for the tariff? Sometimes utilities file rate changes that don't take effect for months.
Ida W. in Chattanooga here. I deal with Duke Energy Tennessee which uses similar rate structures. Check if there's a ratchet provision - sometimes the demand charge is based on either current month demand OR a percentage of the highest demand in the previous 11 months, whichever is higher.
Ed, good catch on the effective dates. I pulled what I thought was current but let me double-check the Duke PSC filings. Ida, interesting point on the ratchet - I don't see obvious language in the LGS schedule but maybe it's buried in the general terms. Will dig deeper.
Wesley F. from Greenville - I'm right in Duke Carolinas territory. The LGS schedule does have a ratchet but it's in Section 7, not with the demand charge rates. It's 80% of the highest demand in the previous 11 months. That might explain your discrepancy if they had higher usage last summer.
Wesley, you nailed it! Went back through 12 months of bills and they hit 308kW last August. 308 x 0.80 = 246.4kW, and 246.4 x $11.86 = $2,922. The small difference is probably taxes or fees. Can't believe I missed the ratchet provision - it was right there in Section 7. Thanks for saving my sanity!
Eddie F. from Orlando. This thread is a great reminder to always check the full tariff document, not just the rate tables. I've made this same mistake with ratchet provisions before. The important stuff is never where you expect it to be.
Irene D. from Dayton. Just wanted to say thanks for working through this publicly. I'm dealing with a similar demand charge mystery with AEP Ohio and this gave me some good ideas on where to look.