Most people assume that the popularity of low voltage cable lighting (also called 'cable track lighting')
today is due solely to the sleek, floating fixture effect common
to this style of lighting. This is largely true, but this type of lighting
is also extremely practical in many challenging design situations.
With an understanding of the basic principles of these systems, they
may be quickly and easily configured for common or challenging
spaces. This article is intended to provide just such an understanding.
Although often lumped into the same category, this type of lighting should not be confused with traditional track lighting, monorail lighting, twinrail or rope lighting systems.
When to use cable lighting
Consider it when unusual ceilings make a traditionally-mounted lighting system impractical. Common situations include rooms with very high ceilings, cathedral or vaulted ceilings and ceilings interrupted by soffits, beams or exposed ductwork. In these situations, short runs (under twenty feet) may typically be installed from wall to wall without any vertical support at all. In situations requiring cable runs longer than twenty feet, additional vertical support is recommended to prevent excessive tension from stressing the mounting points on the wall. These longer spans are easily supported using any combination of a variety of versatile vertical supports.
In spaces with standard, flat ceilings, the use of cable track lighting is largely a matter of design preference over other linear lighting systems such as monorail or traditional track lighting systems. In these situations, dual wire systems offers many of the same benefits.
They are ideal when adjustable lighting is required. If the focal points in the area to be illuminated move often, cable lighting may be a good solution for you. Classic examples of shifting focal points are restaurant tables and art gallery displays, but almost any room without built-in furnishings is a candidate.
Use these systems primarily for accent and task lighting rather than general illumination. Linear lighting systems in general are rarely suitable to illuminate an entire room. Most spaces require a balance of general, ambient illumination, task and accent lighting low voltage cable lighting is best used for task and accent purposes.
Also consider cable lighting if the space to be illuminated has
few points of power. Another reason cable lighting is so practical
is that it allows many fixtures to be powered from a single junction
box. When remodeling, cable lighting is often an easy way to add more
light to the space without requiring installation of more ceiling
junction boxes by an electrician.
A cable lighting system glossary
Cable lighting systems are extremely simple in theory, but a quick review of common cable lighting components is always helpful.
Turnbuckle - Turnbuckles serve two purposes. They attach the cable to a wall or ceiling mount point and, by expanding and contracting in length via a screw motion, they allow tension to be applied to the cable run. Every cable lighting system should include at least one pair of turnbuckles.
Anchor Anchors are similar to turnbuckles in that they attach the cable to a wall mount point. Anchors are very simple, however, and do not allow additional tension to be applied to a system. Short, simple cable runs typically include one set of turnbuckles and one set of anchors. Longer runs may use turnbuckles at both ends to provide extra tensioning ability.
Cable The primary support and conductive cable used in cable
lighting systems is Kevlar-reinforced, tin-plated 10 gauge cable.
Cable is self explanatory and is only mentioned here to
differentiate it from another type of cable occasionally used
in cable lighting systems - aircraft cable. Aircraft cable is used
to provide vertical support for longer cable runs. Aircraft cable
is very thin and should never be used in place of standard cable
lighting system cable.
It should be mentioned that cable lighting system cable is typically bare, but insulated cable is available as well. Insulated cable is commonly used in applications where the cable is passing through walls to be powered by a remote transformer and might come into contact with its sister cable.
Surface mount transformer a transformer, typically housed in a stylish enclosure, attached directly over a power junction box in the ceiling or wall. Surface mount transformers are more common than remote transformers due to their ease of installation during remodeling projects.
Remote mount transformer a transformer, within a metallic housing designed to meet fire code, designed to be mounted in a remote location such as a nearby closet or within the wall itself. Remote mount transformers provide a very clean look and are typically used when installing lighting in a new construction project where access behind walls is available.
Isolating connector used to physically connect two pieces of cable together while breaking the flow of current between them. Since cable lighting systems may only carry 300 watts of power along any part of a run, isolating connectors allow a long cable run to run continuously while being broken into multiple, independently-powered segments.
Vertical support cable runs over 20 feet (or those supporting heavy fixtures) will typically require additional vertical support along the run. Vertical supports are either stem supports or cable supports. Stem supports are rigid pieces of metal (typically from 2 to 24 long) that mount directly to flat ceilings. Cable supports may be any length and are easily installed on practically any irregularly shaped ceiling surface.
Turn kit Cable lighting systems may be turned at almost any angle along the run. This is done using a turn kit which is comprised of a pair of rigid stem supports attached to a cantilevered horizontal support cable. It should be noted that these kits only work on systems running close to the ceiling. Turning systems suspended further from the ceiling is possible, but more difficult.
Using pendants with cable lighting systems
Cable lighting systems support a wide variety of fixtures. Typically, cable lighting systems are used with lightweight track heads (spot lights) designed specifically for such systems. Although pendants may be used, the added weight of glass fixtures will require additional vertical supports along the cable run. Especially heavy fixtures may even require an additional vertical support on each side of the fixture.
Cable lighting limitations
One limitation of low voltage cable lighting systems is that, at the standard 12 volts, they cannot carry more than 300 watts in any length of a cable run. This means that one cable lighting system circuit may power six 50 watt fixtures or eight 35 watt fixtures (both are common bulb wattages.) As mentioned above, this limitation may be overcome by upgrading to a 24 volt transformer or by dividing a cable lighting system into multiple circuits using isolating connectors.
In addition to being sleek and stylish, cable lighting is also a very practical solution when lighting a variety of challenging spaces.