Designing with Light

Neon

This zoomy light source, bringing to mind 1950s casino and bar signs, is generated when electricity passes through a gas. Neon gas, to be specific, glows orange-red (other gases give off a variety of colors). Neon’s low light output makes it undesirable as a functional light source, but it can be bent into all sorts of decorative, sculptural shapes.

Requiring a 24-volt transformer, neon fixtures can be expensive to buy, though they don’t use much energy and may last for years. Newer transformers have reduced the sometimes objectionable buzz emitted from older neon sources.

Neon for home lighting is sold primarily as freestanding pieces though individual artisans or lighting showrooms.

Cold Cathode

Long-lasting cold cathode shines in contoured, confined quarters where other sources fear to tread. Its typical white light is brighter than neon, making it more useful for ambient lighting, and its custom-shaping capability offers decorative flourish.
Cold cathode is often the high-end light of choice for indirect, architectural use and for inaccessible coves and valances where changing shorter-lived bulbs or tubes presents a major challenge. Think of it as fluorescent that can follow a curve. Like neon, cold cathode is available from lighting showrooms and lighting designers.

Really a vehicle rather than a light source, fiber optics carry a light or other media (such as data signals) as if through a tunnel. Put a light source such as halogen or metal halide at one end, and the glass or plastic fiber tubing will beam it efficiently toward the other end.

End-lit fiber optics shine bright light out the open end of opaque fiber cable; edge-lit versions shine all the way along transparent tubing. On one hand, fiber optics function as a decorative alternative to neon or cold cathode, following contoured shapes at will. Unlike neon or cold cathode, however, fiber optics will transmit any color, by shining the light through colored filters.

Fiber optics excel in several other ways, too: the end-lit fiber cable can go places ordinary electrical cable can’t, and it can be covered over; and because there’s no electrical current passing through to use around water, in-doors and out.

On the down side, fiber optics are still quite expensive, and they can be tricky to connect.

HID bulbs produce a lot of light while using a relatively small amount of power. You’ve seen them, but it’s probably been in street lighting or public places. Requiring special fixtures and ballasts, these largish lights may take up to 7 minutes to ignite once switched on. The color emitted by most HID bulbs ranges from mildly to extremely unflattering, metal halide is a noticeable exception.

Mercury Vapor Light

Mercury vapor light is produced by a bulb-within-a-bulb shaped much like an oversize A-bulb. Fixtures are available for garden and security lighting. While color rendering is a ghoulish blue-green, it’s usually acceptable for outdoor uses.

High-Pressure Sodium

High-pressure sodium, a distinctively orangish source, is the number one choice for street lighting. It’s also used indoors commercially and industrially. Like mercury vapor, high-pressure sodium bulbs require a special ballast and fixture.

Low–Pressure Sodium

Low-pressure sodium sports a u-shaped tube within a larger bulb. An even duller orange than its high-pressure counterpart, low-pressure sodium is even more efficient. Thus it’s used extensively for highway and security lighting.

Metal halide is the HID source most likely to come in from the cold in coming years. Why? Its color temperature is far more pleasant than most HIDs, ranging from 3,000 degrees K to 4,000 degrees K. The technology is similar to mercury vapor but almost twice as efficient.

In addition, metal halide bulbs can be made smaller than other HID sources, allowing for more attractive fixtures. While it’s used primarily for outdoor security lighting, metal halide is now also available in table lamp wattages with integral ballasts.