Just got my electric bill for March/April, I get the ticket direct from PEA, the local electric company, even though I rent and there's a management office. They agreed from day 1 (2 years ago) that I'll pay the electric and water directly.
Looking at my bill, if you just take the units used and the headline figure the government rate is 3.6729 per unit. Underneath that is a couple of other bits in Thai that I don't understand (probably standing monthly charge) and a 56 baht refund for something I again don't understand, but that total divided by the units used is 3.9527 per unit.
With the tax at 7%, if that's added then a unit cost worked out it's 4.2293 per unit.
Whichever calculation is used, at 10 you're paying over double the government rate, so definitely OTT.