She felt an urgency to get on with the case but she also wanted to hear what he had to say. "I don't have much time, but please, go ahead."

"First, you have to know how dangerous electricity is. And that means knowing about amperage, or current. You know what that is?"

"I…" Sachs had thought she did, until she realized she couldn't define it. "No."

"Let's compare an electric circuit to a plumbing system: water pumped through pipes. Water pressure is created by the pump, which moves a certain amount of water through the pipes at a certain speed. It moves more or less easily depending on the width and condition of the pipes.

"Now, in an electrical system, it's the same thing. Except you have electrons instead of water, wires or some conductive material instead of pipes and a generator or battery instead of the pump. The pressure pushing the electrons is the voltage. The amount of electrons moving through the wire is the amps, or current. The resistance-called ohms-is determined by the width and nature of the wires or whatever the electrons're flowing through."

So far, so good. "That makes sense. Never heard it put that way before."

"Now we're talking about amps. Remember: the amount of moving electrons."

"Good."

"How much amperage does it take to kill you? At a hundred milliamps of AC current, your heart will fibrillate and you'll die. That's one tenth of one amp. Your typical Rite Aid hair dryer pulls ten amps."

"Ten?" Sachs whispered.

"Yes, ma'am. A hair dryer. Ten amps, which, by the way, is all you need for an electric chair."

As if she weren't uneasy enough.

He continued, "Electricity is like Frankenstein's monster-who was animated with lightning, by the way. It's stupid and it's brilliant. Stupid because once it's created it wants to do only one thing: Get back to the ground. Brilliant because it instinctively knows the best way to do that. It always takes the path of least resistance. You can grab on to a hundred-thousand-volt line but if it's easier for the electricity to get back through the wire, you're perfectly safe. If you're the best conductor to the ground…" His pointed nod explained the consequences.

"Now, for your lesson. My three rules for dealing with juice: First, avoid it if at all possible. This guy is going to know you're after him and he might be rigging traps with live lines. Stay away from metal-handrails, doors and doorknobs, uncarpeted flooring, appliances, machinery. Wet basements, standing water. Have you ever seen transformers and switchgear on the street?"

"No."

"Yes, you have. But you're not aware of them because our city fathers hide and disguise them. The working parts of transformers're scary and ugly. In the city, they're underground or in innocuous buildings or neutral-painted enclosures. You could be standing right next to a transformer taking in thirteen thousand volts and not know it. So keep an eye out for anything that says Algonquin on it. And stay away if you can.

"Now, you have to remember that even if you think you're avoiding it, you could still be in danger. There's something called 'islanding.' "

"Islanding?"

"Say the grid is down in some part of town, like happened today. You think all the circuits're dead, right? Of course you're safe. Well, maybe and maybe not. Andi Jessen would like Algonquin to be the only game in town, but we're not. Power nowadays is supplied through what's called distributed generation, where smaller energy producers pump juice into our grid. Islanding would happen when the Algonquin supply is offline but some smaller source is still supplying juice to the grid-an island of electricity in the void.

"Then there's backfeed. You cut the breakers on a line and go to work. But the low-voltage lines downstream may start feeding juice back into the transformer-"

Sachs understood. "And the transformer steps it back up."

"Exactly. And the line you thought was dead is alive. Really alive."

"With enough juice to hurt you."

"Oh, yeah. And then there's induction. Even if you're sure you shut off the circuits-it's completely dead, and there's no islanding or backfeed possible-the wire you're working on can still become charged again with deadly voltage if there's another live wire nearby. That's because of induction. The current in one wire can energize another, even a dead one, if it's close enough.

"So, rule one: Avoid the juice. What's rule two? If you can't avoid it, protect yourself against it. Wear PPE, personal protective equipment. Rubber boots and gloves and not those sissy little ones they wear on that CSI TV show. Thick, industrial, rubber work gloves. Use insulated tools or, even better, a hot stick. They're fiberglass, like hockey sticks, with tools attached to the end. We use them for working live lines.

"Protect yourself," he repeated. "Remember the path-of-least-resistance rule. Human skin is a pretty poor conductor if it's dry. If it's wet, especially with sweat, because of the salt, resistance drops dramatically. And if you've got a wound or a burn, skin becomes a great conductor. Dry leather soles of your shoes are fairly good insulators. Wet leather's like skin-especially if you're standing on a conductive surface like damp ground or a basement floor. Puddles of water? Uh-oh.

"So, if you have to touch something that could be live-say, opening a metal door-make sure you're dry and wearing insulated shoes or boots. Use a hot stick or an insulated tool if you can and use only one hand-your right since it's slightly farther from the heart-and keep your other hand in your pocket so you don't touch anything accidentally and complete a circuit. Watch where you put your feet.

"You've seen birds sitting on uninsulated high-tension wires? They don't wear PPE. How can they roost on a piece of metal carrying a hundred thousand volts? Why don't we have roast pigeons falling from the skies?"

"They don't touch the other wire."

"Exactly. As long as they don't touch a return or the tower, they're fine. They have the same charge as the wire, but there's no current-no amps-going through them. You've got to be like that bird on the wire."

Which, to Sachs, made her sound pretty damn fragile.

"Take off all metal before you work with juice. Jewelry especially. Pure silver is the best conductor on earth. Copper and aluminum are at the top too. Gold isn't far behind. At the other end are the dielectrics-insulators. Glass and Teflon, then ceramic, plastics, rubber, wood. Bad conductors. Standing on something like that, even a thin piece, could mean the difference between life and death.

"That's rule number two, protection." Sommers continued, "Finally, rule three: If you can't avoid juice and can't protect yourself against it, cut its head off. All circuits, big or small, have a way to shut them down. They all have switches, they all have breakers or fuses. You can stop the juice instantly by flipping the switch or the breaker off, or removing a fuse. And you don't even need to know where the breaker is to pop it. What happens if you stick two pieces of wire into the holes in a household outlet and touch the ends?"

"The circuit breaker pops."

"Exactly. You can do the same thing with any circuit. But remember rule number two. Protect yourself when you do that. Because at bigger voltages touching the two wires will produce one hell of a spark and it could be an arc flash."

Sommers was on to another junk food course, pretzels. He washed down the noisy bite with more soda. "I could go on for an hour but those're the basics. You get the message?"