Electricity is one thing most people take for granted - until power is temporarily lost.

The public today has a tremendous expectation for reliability of electricity, according to Steve Rush, north Davis County district manager for Utah Power & Light in Layton.Rush said this expectation is mainly generated by reliance on today's electronic devices - digital clocks, VCRs and computers. He said that even if a family isn't home during an outage, they'll return and know that there was a power failure because of flashing lights on devices in their house.

"We're 99.99 percent reliable," Rush said. "Our goal is to have no more than 100 minutes of power outages a year per customer."

However, occasional power losses do occur, and here are some important questions about outages and answers supplied by Rush:

Q: Are some areas more susceptible to power outages than others?

A: Some areas are indeed more susceptible to power outages because of several factors, such as high winds near the mouths of canyons that can blow power lines together or even down.

"The biggest problem when we get a big wind is the trees that have grown into the power lines," Dave Eskelson, spokesman for UP&L, said recent storm. "Either the branches go down and take the lines with them, or they push the lines together close enough to make them arc."

Q: During a storm, it is understandable that the likelihood of a power outage increases, but what about outages or power disruptions that occur during calm weather?

A: Power lines are also vulnerable to non-weather accidents. Rush said digging accidents are a major problem. Mention the word "backhoe" and he shudders. He said that most power lines are only buried 42 inches deep and too many residential customers don't call "Blue Stakes" before they dig.

"Murphy's Law says that they'll find the power line," he said.

Still other occasional outages are caused by UP&L equipment failures.

Construction in a particular area can also cause problems. For example, west Layton, where residential, commercial and highway construction is going on, has been particularly hard-hit by outages this year with three one-hour-plus outages and four or more brief disruptions.

Shifts in power load relating to relocating a main power line on Antelope Drive because of the road construction there has caused several electrical fluctuations this month.

Several hour-plus outages in Layton were caused by accidents. In one, a car struck a power pole and in another, workers constructing a transmission tower bumped a a power line with a crane. Still another outage was planned at about 5 a.m. one day because of necessary maintenance by UP&L that couldn't be performed on a live line.

Rush said some accidents cause only a short in the power line, making a breaker temporarily open up. This results in a brief power fluctuation or "trip" as the line tries to clear itself. This tripping of a circuit breaker can happen three times before the breaker locks in the open position.

Depending on what fuses close, one street might lose power while an adjacent street has no disruption. When restoring power, it is sometimes done in stages - perhaps taking only 15 minutes for one neighborhood to return to power and an hour for another.

Q: How does UP&L know there is an outage?

A: Rush said telephoning the power company is a critical process in getting power restored. He said that unless it's a major outage, UP&L doesn't know about a problem until customers phone in. This calling process also helps the company identify the area or areas involved. Rush cautioned against customers assuming that UP&L already knows about an outage or that many others affected by it have already called in. It's always best to call, he stressed. Telephone lines are generally unaffected by power outages since they have their own power supply.

Q: How long does it usually take to restore power?

A: It depends on what happened and even when it happens. Rush confirmed that power outages during the hours of 8 a.m. to 4:30 p.m. will always be corrected more quickly because manpower is readily available to fix the problem.

"During other hours, we have to bring a crew in," Rush said.

He said that most of the time involved in restoring power is spent in actually finding the source of the problem. A crew has to look for fuses that may be open on a pole or other problems.

Q: Sometimes before a power outage, a big boom - like a shotgun blast - is heard. What causes that?

A: Rush said that "T-link fuses" along a power line are rigged to actually blow their arms apart in the event of a serious electrical problem. The fuses contain tin and arc suppressors. When they burst apart, they do sound like explosions, but this process is a necessary safety measure.

Q: Are underground power lines or overhead power lines more reliable?

A: This is "a two-edged sword" situation with advantages and disadvantages that "kind of even out." Overhead lines are easier to troubleshoot, while problems are much more difficult to locate in underground lines. Underground lines don't detract from the appearance of a neighborhood and aren't susceptible to wind problems, but people aren't aware of them like they are wires on poles and so they are damaged more frequently by digging.

Rush also said the life span of some underground lines hasn't proved to be nearly as long as expected. Small nicks in the wires during hasty installation, corrosion or water damage can cause problems.

Q: If only your house seems to be having a power problem, how do you know when to call the power company instead of an electrician?

A: UP&L is responsible for the power up to the electric meter. It doesn't handle internal wiring, but . . ."It doesn't hurt to phone us and describe the problem," Rush said. "Let us make the judgment."

Some electrical problems relating to partial power or a loss of 220-volt power can be caused by shorts in underground cables. When in doubt, call the power company first. A customer may then save an unnecessary service call from an electrician - if the problem is outside the house.

Q: Why do some VCRs or electronic clocks reset themselves and/or flash after brief power fluctuations, while others do not?

A: Some VCRs and clocks have battery backups to prevent being reset by brief power disruptions.

Q: Why do some electronic devices, like computers, need surge protectors?

A: Rush said that these protectors prevent damage from surges of power along lines, caused by such things as lightning. He suggests contacting a computer dealer for specific information but cautioned against relying on inexpensive power surge devices in the event of an actual, major power surge.