CHAPTER 3 ■ SAFETYGFCI (Ground Fault Circuit Interrupter) outlets are often found in bathrooms and kitchens. Unlike
circuit breakers that detect too much total power, GFCI outlets disable power when not all of the electricity
being sent out from the outlet is returning. This is more likely in wet conditions, where the water provides an
electrical path from the device to your body. Like circuit breakers, GFCI outlets can be lifesavers.
Another place to consider a fuse or circuit breaker is on the robot itself. The portions of the circuit with
regulated power go through a voltage regulator chip. So, check their datasheets to make sure your regulator
chips have built-in thermal and current overload mechanisms (most do).
For circuits on the robot that connect directly to the battery, such as the motors, use a fuse or circuit
breaker to prevent damage or fire.
PPTC (Polymeric Positive Temperature Coefficient) switches (see Figure 3-8) resist power flow when
overheated by too much current. A few seconds after the fault is corrected, they cool down and automatically
reconnect the power. They’re lightweight, inexpensive, and can be placed deep within a robot since the user
doesn’t need to press a button to reset the circuit breaker.
Figure 3-7. A circuit breaker built into an outlet strip