Why can't I get ANY electric heating pad to heat up past the lowest temperature setting?

I have purchased 3 different electric heating pads over the past 2 months, but all of them barely even get warm on the highest setting (they're supposed to reach 140 degrees F). They can't ALL be defective. Is there some sort of electrical issue that could cause them to not heat up all the way?
Answers

AlCapone

Maybe. Do other appliances work OK plugged into the same outlet? Have you tried other outlets? If all three of your pads are the same model from the same company, try a different model from a different company.

DR + Mrs Bears face

Hi as it will destroy itself.

don r

Check your ac outlet voltage. If it's less than 100 volts make the utility company fix your wiring.