@zerkms the low user rate has higher per unit costs. The cutoff is 667 units per month. More than this you will be better off as a standard user. Also the rules make assumptions on how much of your usage is controlled and uncontrolled and / or day and night. If you have different usage ratios. This would also affect if you should be on standard user or low user.

Also keep in mind that if you are on low user. And you happen to have an unusually large bill that takes you way over the 667 unit cutoff. That bill will be very expensive for the month. So sometimes it is better to be on standard user even if the raw usage says that low user is better. So you don't have as much winter bill shock. And you also get bragging rights from having a lower unit rate.