Hot Water Heater And automatic Cut- off?

[Thunderman]

I inadvertently left a hot water heater on (electric) without water. I realized this sometime later, I called the dealer and he said not to worry because they have an automatic cut-off switch for this. Later the unit did heat water properly. Was I lucky or is there a automatic switch on all heaters? Thanks!

Weldon and Carolyn
2001 F-250 PSD, CC
2003 2955RL Montana