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Have you ever wondered why shoes hanging on a power line don’t get fried? Now you can get answers to these and all your energy-related questions. Just Ask an Expert!

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Answer: A circuit is a closed path or loop that is needed for electricity to flow. Electricity flows when a circuit is closed (that is, the circle is complete), and will not flow when a circuit is open. You can access a circuit-building activity experiment on our website here.

Answer: California condors almost went extinct because they have a slow rate of reproduction and many adult condors were killed through contact with power lines. Condors have a nearly 10-foot wingspan, making it easy for them to bridge between two power lines or to touch a power line and pole at the same time—both of which can be deadly. Learn more about how a training program that taught condors to avoid power poles in the World of Wires section of this website.

Answer: Climbing a tree near a power line is super dangerous! I’m afraid you’ll need to stop climbing your favorite tree, and find a new one to climb that is located far away from power lines. To learn more about this, read the section on the dangers of trees and powerlines on this website.

Answer: Another student named Will asked this question a while back – if you click on See More Questions at the bottom of this page you can find it. But for convenience, I’ve provided my answer again.

Shoes hanging on a power line don’t get burned for the same reason that birds standing on a power line don’t get shocked: they don’t give electricity a path to the ground, so electricity stays in the line and does not go through them. But if the shoes were to touch a power line and a power pole at the same time, they would provide a path to the ground and would get blasted with electric current. It wouldn’t be pretty!

By the way, if you ever see someone throwing shoes up onto a line, tell them to stop! The shoes can damage the power line, or someone trying to get the shoes down could be seriously shocked or even killed.

Answer: You were lucky enough to be dealing with a well-designed copier and only an inch of water. Assuming the wall outlet was well above the waterline and the power cable and plug were dry, you were in no danger. The blue spark you saw was an arc between the outlet socket and the copier plug caused by the current trying to jump the gap and complete the circuit. Evidently the machine was properly insulated, so there was no way for an inch of water to get into it and cause a short circuit. However, if the water level had been higher and had caused a short in the machine, or if the cord had been wet, you could have been electrocuted when you pulled the plug. The correct first thing to have done would have been to switch off the copier, using an insulating object like an eraser to push the switch as an extra precaution, so that current no longer flowed through the machine. Only then would you unplug it at the wall.

Answer: One lightning strike can carry 100 million to 1 billion volts of electricity. That’s the equivalent of your being hooked up to between 8 and 80 million car batteries! Although the chances of getting struck by lightning aren’t terribly high, you do not want to risk it. You can read about lightning shock survivor Carissa here on this site. Carissa was lucky in that she wasn’t paralyzed or killed!

Answer: Conductors are materials through which electricity travels easily. Water and metal are good conductors, which is why you should avoid using electricity near water. It’s also why you should stay far away from metal objects and bodies of water during a lightning storm: if lightning strikes nearby, water and metal can conduct electricity right through you! “Insulators” do the opposite thing from conductors—they insulate from (or block the flow of) electricity. You can read more about conductors and insulators here.

Answer: Some 120-volt plugs have two vertical prongs and a round one centered below them. The left prong is neutral, the right prong is hot, and the round one is the ground. The prongs on a plug fit into the slots in a wall outlet. Electricity flows in a circuit, so the appliance you plug into an outlet completes the circuit from the hot slot to the neutral slot, and electricity flows through and powers whatever you plug in. The ground prong connects to a wire that is grounded, or connected with the earth.

It’s actually the breaker box on the side of your house that prevents fires and short circuits, because it detects electricity overloads and flips the breaker to open the circuit. But here’s where the ground prong comes in. Because metal conducts electricity, every appliance with a metal casing (including computers, power tools, electronics, and most appliances) should have a three-prong plug for safety. The casing is directly connected to the ground prong, so if electricity escapes from the wiring inside, it will flow straight through the breaker box into the earth (instead of energizing the metal parts of the device). This will trip the breaker in the breaker box, so the appliance stops working instead of delivering an electrical shock to whoever is using it.

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Answer: Electric and magnetic fields (EMFs) are created around appliances and wires wherever a voltage exists. Significant research has been conducted internationally over the last 40+ years to evaluate the potential health impacts of EMF exposure. There is no definitive answer as to whether EMF exposures cause adverse health effects. After reviewing more than two decades of research in this area, scientists from the National Institute of Environmental Health Sciences (NIEHS) concluded that the evidence supporting EMF health risks was weak, but still sufficient to warrant limited concern due to a possible weak association between increasing exposure to EMFs and an increased risk of childhood leukemia. In general, they concluded that studies conducted on adult exposures do not support a link between residential EMF exposure and adult cancers.

A 2007 World Health Organization (WHO) report concluded that evidence for a link between magnetic fields and childhood leukemia is not strong enough to be considered a cause, but it’s sufficiently strong to remain a concern. For all other diseases, the WHO classified the evidence of health effects at low exposure levels as inadequate. For more information, visit

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