I received an email last week from someone who has an interesting problem. She can no longer turn off the exhaust fan in her bathroom! When she throws the switch into the off position, the fan keeps running. We haven't talked about AC yet, but that is not important to the problem. Below is a diagram of a typical wiring scheme, where a simple DC battery is shown in place of the AC potential.
It is important to note that the negative side of the battery is grounded, indicated by the triangular shaped symbol with horizontal lines. That means the negative side of the battery is connected physically to the earth, usually through a wire or steel rebar within the house structure. (Next week we will discuss why something similar to this is done with AC potentials.
What do you think could cause this peculiar problem? Remember that all the wires are within walls and ceilings.
BE SURE to enter your full name. Enter your email address and CHECK that it is correct! Responses should be brief but complete. You must click the SUBMIT button to submit your entry. (You should receive a "Thank You" reply almost immediately.) Entries are due by noon on Monday of next week.
NOTE: Only your first submission will be accepted!