12 v versus 120 v

    

Low voltage systems are more appropriate in residential settings; line voltage systems are better suited to large-scale commercial and institutional applications. The pros and cons of 12v and 120v are summarized as follows:

12v

120v

flexibility when installing or relocating; cable is only hidden

wire must be buried 18 inches and/or placed in a protective conduit; difficult to move

designed for wet locations and operate safely when exposed to moisture

all fixtures and connectors must be absolutely waterproof; shock hazard potential when wet

lamps (light bulbs) are small and allow fixtures to be smaller and less obtrusive in the landscape

lamps much larger and require larger fixtures to house them

lamps available in low watt type and many beam spreads; more precise lighting effects can be achieved with lower energy costs

higher watt lamps and one or two beam spreads produce inappropriately high light levels; lack of beam control creates glare problems; more expensive to operate

can be plugged into existing outdoor receptacles; no need for an electrical contractor in most cases

must always be installed by a licensed electrical contractor; local permits may be required

transformer to convert current from 120v to 12v required; voltage drop (dim lights) can occur if improperly engineered and inadequately sized cable used

no transformer required; voltage drop not as critical


The appeal of good lighting is mainly a matter of individual taste but some common deficiencies in lighting design are easy to identify:

  • High surface brightness - the funeral home or model home look

  • High contrast ratios - hot spots of bright light surrounded by large dark areas

  • Lack of variety in the lighting techniques - or the opposite: overly dramatic effects

  • Lighting that shines into the widows of the home or into neighboring homes

  • An over abundance of path lighting too closely spaced - the runway effect

  • Unbalanced lighting that divides rather than unites the landscape features

  • Glare from unshielded sources that detract from the intended effects

  • Dim lights or large variations in light-to-light brightness indicate improper engineering