The spark happens when you turn it off also. In fact, it can be a bigger spark when disconnecting. Make sure you do not turn off the lights till after sundown.
Also:
According to the
University of Hawaii, “When two objects are rubbed together to create static electricity, one object gives up electrons and becomes more positively charged while the other material collects electrons and becomes more negatively charged.” This is because one material has weakly bound electrons, and the other has many vacancies in its outer electron shells, so electrons can move from the former to the latter creating a charge imbalance after the materials are separated. Materials that can lose or gain electrons in this way are called triboelectric, according to
Northwestern University. One common example of this would be shuffling your feet across carpet, particularly in low humidity which makes the air less conductive and increases the effect.
In addition to causing in a painful shock, these sudden high-voltage discharges can provide a source of ignition for flammable substances, according to the
Occupational Safety and Health Administration (OSHA). Static shock can also damage delicate electronics. According to
NASA, a simple spark from a finger can damage sensitive components and render them unusable, so precautions must be taken such as keeping circuit boards in conductive plastic bags and wearing grounding straps to dissipate static charge continuously from your body.
Another source of static charge is the motion of fluids through a pipe or hose. If that fluid is flammable — such as gasoline — a spark from a sudden discharge could result in a fire or explosion. People who handle liquid fuels should take great care to avoid charge buildup and sudden discharge. In an interview, Daniel Marsh, professor of physics at Missouri Southern State University, warned that when putting gasoline in your car, you should always touch a metal part of the car after getting out to dissipate any charge that might have developed by sliding across the seat. Also, when buying gas for your lawn mower, you should always take the can out of your car and place it on the ground while filling it. This dissipates the static charge continuously and keeps it from building up enough to create a spark.
I guess we can't walk on a carpet on the Sabbath either! I mean, how far do you go with this??