Monthly Archives: July 2011

Recessed Lighting

As with any other home product, some types of recessed lighting are more energy efficient than others. Efficient options can use 80 percent less electricity than inefficient versions which provide the same amount of light output with practically the same appearance. At Electric Services Los Angeles, we can install, repair, and maintain recessed lighting and other electrical services.

What Do I Need To Know About the Installation of Recessed Lighting?

Recessed light fixtures are unique because they penetrate and are mounted in the ceiling of a room. From an energy conservation standpoint, this is not an issue when installed in the first floor ceiling of a two-story house. However, if fixtures are installed in the second-story ceiling or the first floor ceiling of a one-story house, a hole is created between a conditioned living area and the open, unconditioned attic area.

Recessed Lighting

Recessed Lighting

Without an efficient design and proper installation, a recessed lighting fixture can allow conditioned air to leak out of the house. This is particularly true during winter, when the warmer air inside a home naturally rises to the ceiling. This not only wastes energy, but may create a chilly draft in rooms where cold outdoor air leaks indoors.   There are new energy-efficient recessed light designs that meet Energy Star standards. All of these fixtures use fluorescent light sources instead of inefficient incandescent bulbs. This fact alone reduces electricity consumption by 75 percent. The inside surface of the new fixtures is also more reflective, which reduces the amount of light trapped and dissipated inside a fixture before ever getting into a room.   For fixtures in ceilings where indoor air leakage seems likely, select a new airtight design with a sealed canister. When installed properly, this unit forms an airtight seal between the ceiling and the fixture. These types of fixtures are most often used in ceilings beneath an unconditioned attic, but they are also effective for unheated basement ceilings, minimizing drafts between floors.   As a safety note, if you already have recessed lighting in your home, do not go into the attic and wrap them with insulation to try to save energy. Wrapping older fixtures with insulation can hold in too much heat, particularly when standard incandescent bulbs are used. These fixtures are not designed to be airtight and the excess heat buildup can become an electrical or fire hazard.   If recessed lighting will be installed in a ceiling under an insulated attic floor, select an insulation contact-rated (IC) design. These are designed to touch insulation without overheating the fixture. When installing new non-IC fixtures, the insulation must be kept away from the canister. This insulation void increases heat loss from the room below even if the installation is airtight.   When installing recessed light fixtures yourself, first determine your lighting goals. To brighten an entire room, downlighting can be quite effective. In a normal-height ceiling, a 4-foot spacing provides an even lighting pattern at floor level. Typical 6-inch-diameter fluorescent fixed vertical fixtures work well for downlighting. If you’d like to dim some of the lights, consider installing a second circuit and dimmer switch with incandescent bulbs in those fixtures.   For task lighting, a single fixed vertical unit directly over the work area seems effective. Wall-wash recessed lighting can be used to accent a painting or other wall hangings. An eyeball recessed light is best for this application because the light path can be adjusted. For a sloped cathedral ceiling, install an angular recessed fixture—preferably an IC model, since it will contact with ceiling insulation.   It’s not difficult to install recessed lighting fixtures by yourself. For an attractive, efficient installation, cut the mounting holes the exact size recommended by the manufacturer. This makes it much easier to create a good seal between the fixture and the ceiling. Before drilling and cutting holes, make sure your fixture layout clears all the floor joists. For a free estimate, please contact Los Angeles Electricians today!

Preventing Electrical Damage

Fuses and circuit breakers can both be effective in preventing electrical damage. Here are some points of comparison. WHAT DO WE MEAN BY protection? We mean preventing electrical damage. We do not mean fault prevention. No protective device can function until a fault has occurred, triggering device operation. And a fault, by definition, represents some sort of damage. At Los Angeles Electric Services we install, repair, and maintain circuit breakers and fuses.

Preventing Electrical Damage

Preventing Electrical Damage

In a motor circuit, one way of preventing electrical damage is furnished by the starter overloads. They don’t prevent overloading, blocked ventilation, or other causes of winding overheating or overcurrent. What they do is sense excessive current and act to take the motor off the line before damage results.

The second way of preventing electrical damage, with which we’re concerned here, comes into play when overheating, a voltage surge, or some other condition causes a fault within the motor winding. Without circuit breakers protection, the resulting “fault current” would quickly escalate the damage. That could occur either within the winding itself (possibly complete burnout with core damage), in the motor starter, or in the circuit wiring. Attention in recent years has centered particularly on preventing that starter damage, by providing what the International Electrotechnical Commission has called Type 2 circuit protection.

Type 2 circuit protection involves what the National Electrical Code (in Section 430.1) defines as “Motor branch-circuit short-circuit and ground fault protection.” Immediately upstream from that way of preventing electrical damage, the Code also mandates a “Motor disconnecting means.” These two functions are normally combined in one of two packages: either a fused disconnect switch, or a circuit breaker (see diagram, next page).

Again-this is not “motor protection.” Some types of fuses will indeed respond to fault current within a winding. But no such current can exist until a damaging fault has already occurred; all the fuse can do is as far as preventing electrical damage is to prevent additional damage beyond that. Hence, either the fuses or the breaker are customarily considered “circuit protection.”

Which method of preventing electrical damage is better? Properly designed, either is effective, making the choice usually a judgment call. In some industrial installations (especially utility generating plants), breakers are favored because operators cannot readily determine fuse integrity. When fused equipment is supplied, some plant personnel have been known to replace fuses with solid copper rods (and add upstream circuit breakers) so no question of fuse condition will arise.

Which Method Should I Choose In Preventing Electrical Damage?

For decision-making on more objective grounds, here are some points of comparison:

1. Favoring fuses:

a. Lower cost.

b. No moving parts; contact welding not a problem.

c. No need for periodic “exercising” to verify capability.

d. Current-limiting capability to 300,000 amperes.

On the other hand: repeated motor starts can fatigue fuses.

2. Favoring breakers:

a. Common trip bar eliminates single-phasing possibility; all phases trip together.

b. More compact.

c. Many can be fitted with electric shunt-trip attachments for GFI protective schemes.

d. Can be reset following a fault; no need to replace.

e. Not subject to accidental operation through fatigue.

f. May operate faster than fuses at low levels of fault current.

On the other hand, re-setting a tripped breaker can be dangerous because it may be reclosing on a fault.

Other concerns affecting either alternative: Individual fuses may be replaced with an incorrect item; the same is true of the smaller circuit breakers. Also, fuses are subject to high resistance connections, resulting in overheating and unbalanced downstream voltage, at their mounting clips. Circuit breakers, using screw lug connections instead, have been subject to the same problem (particularly where aluminum/copper interfaces exist). A sound maintenance program will include periodic infrared surveys of all such connections. Knowing when the device has operated once required testing of fuses, whereas the breaker’s status could be seen from its operating handle position. However, “blown fuse indicators” are now widely available.

At one time, the fast-acting (generally in less than a quarter cycle) current-limiting capability of some fuses offered a clear advantage. Current– limiting breakers have now been developed, however, with ratings up to 200,000 amperes. In most circuits, then, either fuses or breakers can limit let-through current and energy equally well.

Don’t let such numbers fool you, however. A 300,000 ampere interrupting rating for a fuse simply means that the device will quickly interrupt the short-circuit current that can be drawn from a system capable of supplying 300,000 amperes. Actual current flow through the fuse never approaches that value. If it did, the fuse would be vaporized. The same applies to a circuit breaker.

With either whichever choice you make regarding preventing electrical damage, proper operation depends upon selective coordination between branch-circuit protection and what exists upstream. In addition, device function needs to take into account the protection requirements of the circuit conductors– not just the motor rating.

For a free estimate, please contact Los Angeles Electrician today!