Frequently Asked Questions
Does it shorten the life
of an LED bulb to turn it off and on?
No, unlike fluorescent
bulbs, LED lighting is not affected by being turned on or off.
Do LED light bulbs come
on instantly or do they have a delay like compact fluorescent lights (CFLs)?
Most LED lights switch
on instantly at full brightness just like incandescent or halogen bulbs. They do not suffer from the “blooming” effect
of CFL bulbs.
Where are the best
places to put LEDs in my home or business?
For the quickest return
on investment one should look for locations where the lights are left on the
longest amount of time. These areas usually
include the kitchen, common spaces, outdoor security lights, office hallways
and lobbies. Due to their long life, LED lights are also ideal for hard
to reach spots like high ceilings cans or track lights. From a quality of
light standpoint, LED lights offer a very energy efficient dimmable light with
a high color rendering index number.
Can all LED lighting be dimmed
or used with dimmer switches?
The quick answer is no,
not all LED lighting can be used with dimmer switches. Make sure to buy a LED light bulb or light
fixture that specifically states on the packaging, or within the product
description, that it’s dimmable. Also,
be sure to look at any additional requirements the lights may have in order to
dim properly. This may include using low
voltage electronic or magnetic dimmers or making sure to have enough LED light
bulbs on a dimmer so that the lights dim to their lowest possible setting. The dimmer switch you already have may work
great, but be prepared for the possibility that another type of dimmer switch
may work better. For more information, please see our Dimming LED Lighting article.
How come some LED lights
last longer than others?
All light bulbs suffer
from a diminished amount of light output over time. However, unlike incandescent light bulbs, LED
light bulbs don’t typically fail completely but continue to lose brightness
over thousands of hours. The industry considers an LED light bulb’s life span
to be over when it reaches 70% of its initial brightness. Most well designed
LED lights will last 25,000 to 50,000 hours. The actual lifespan of an LED
light depends on several factors. Heat is produced around the LED chip
and causes an accelerated decrease in the life and performance of an LED light
if not dealt with properly. A well designed LED light will have high
quality components designed to move the heat generated by the LEDs away from
the LED itself. Also, some lesser quality LED bulb makers overdrive the LED
inside the bulb with more electrical current than they are designed to
handle. This will yield more initial brightness from the LEDs but results
in a shortened lifespan and shifts in color temperature. WARNING:
Manufacturer’s who claim 100,000 + hours for their LED lights are publishing a
half truth because they are typically making claims based on lab tests of the LED
chip itself and not the LED light bulb or LED fixture as a whole!
What about using LED lighting in fully enclosed housings?
As mentioned in the previous question, LED light bulbs do not like excessive heat particularly around the LED chip and circuitry. Operating LED bulbs in tightly enclosed spaces results in higher ambient temperatures and reduces the ability of the bulbs to dissapate heat. This may result in a dramatic decrease of bulb life and shifts in color temperature of the light being produced. If possible, always try to provide some means of airflow to allow for convective cooling around the LED bulb. Many LED bulb manufacturers include product labeling stating that their bulbs are not for use in totally enclosed fixtures and that doing so will void the warranty on these products.
What does Color Temperature
(CT) or Correlated Color Temperature (CCT) refer to?
LED lighting is available
in a wide range of color temperatures from the warm yellow color of an
incandescent bulb to the neutral color of a halogen to a cool blue color
similar to a bright but overcast day. We recommend familiarizing yourself with
the color temperature scale used to define what hue of light a specific LED bulb
emits. Color temperature is based on the
Kelvin temperature scale, measured in degrees, and ranges from 2600°K on the low
end to over 6000°K on the high end for most lighting applications. Most home applications should utilize
lighting with a CCT at or below 4000°K. Light emitted above 3500°K is
popular for commercial environments or very modern decors that seek to
reproduce a daylight look.
Do LED bulbs emit UV and IR radiation?
Most LED bulbs produce a "cold" beam that contains only visible light. In other words, no ultraviolet (UV) or infrared (IR) light is emitted. There are several advantages to using a light that only emits electromagnetic radiation in the visible spectrum, as a light withouth UV or IR will not fade colors, degrade artwork or radiate thermal energy (heat) in the beam. This makes LED lighting an ideal candidate for retail shops, galleries and museums, all of which need lighting with good color rendering and that won't adversely affect the merchandise or art displays.
What does Beam Angle refer to?
Knowing the beam angle of a light bulb helps to
ensure that you’re buying a product which will give you adequate lighting in a
particular application. Light bulbs are often referred to as ‘spotlights’ or ‘floodlights’,
and while these terms do relate to beam angle, they still leave some ambiguity
due to the wide variation of bulbs that fall into each particular category. For instance, one floodlight bulb may have a
beam angle of 30° while another may have a beam angle of 75°. Quite a difference! Beam angle specifically refers to the angle
at which the light output has been reduced to 50% of the maximum center beam brightness.
For instance, let’s say a PAR30 LED light bulb has a center beam candlepower
measurement of 800. If at 30° to one
side of the beam the candlepower has dropped to 400 then we know that the beam
angle is 60° (see diagram below). It's best to buy
spotlight bulbs when trying to highlight a particular object or concentrate
light in a smaller area. Use floodlight
bulbs when trying to achieve more general illumination, such as in recessed
What is a lumen?
In layman’s terms, lumens are a measurement of light
output. The technical definition goes
beyond the scope of our frequently asked questions, but the fact is that knowing
something about the lumen is becoming much more important as we move away from
using traditional light bulbs. With
incandescent lighting most people are used to associating brightness with certain
wattages (i.e. a 100W bulb is brighter than a 75W bulb), but wattage is really
a measurement of the power required to light the bulb and not a measurement of
light output. A 60 watt incandescent
bulb produces about 800 lumens of light and yet an LED bulb can output the same
amount of light using 12 watts or less. It’s
the lumens that are really important here, and the less wattage it takes to supply a
given amount of light the better and more efficient your lighting really is. In the near future most types of light bulbs
will require the lumen output to be listed on the bulb packaging. This will make it much easier to compare
different types of lighting and how efficient they are.
What is the Color Rendering Index (CRI)?
The Color Rendering Index is a measurement of how
accurate certain colors look when viewed under the light from a particular
light source as compared to an ideal or natural light source radiating at the same
color temperature. The CRI of a bulb
does not relate to the color of light the bulb produces. That falls under the Color Temperature measurement
(see above). The index scale ranges from
0-100 with 100 being a perfect score. There
is some discussion in the lighting world that CRI will not accurately reflect the
ability of new lighting technologies to render colors properly and new methods are
being looked at for measuring this component of lighting. It can certainly happen that people may think
colors look more accurate to their eye under a light source with a lower CRI
than one with a higher CRI. When it comes to LED lighting the current
recommendation is to purchase products with a CRI of 80 or higher.
Is LED lighting suitable for damp or wet locations?
Many LED lighting products are UL listed as 'Damp Rated' or 'Wet Rated' and can be used in locations where moisture has the possibility of condensing or coming in direct contact with the light. Just what do all the different UL environmental location markings mean? We're glad you asked. Here's the answer from the the UL Marking Guide for Luminaires:
1. DRY LOCATIONS — A luminaire intended for use in a location not normally subject to
dampness, but may include a location subject to temporary dampness, as in the case of a
building under construction, provided ventilation is adequate to prevent an accumulation of
moisture is marked “DRY LOCATIONS ONLY.”
2. DAMP LOCATIONS — Only luminaires marked “SUITABLE FOR DAMP LOCATIONS” or
“SUITABLE FOR WET LOCATIONS” are intended to be installed in damp locations. A damp
location is an exterior or interior location that is normally or periodically subject to condensation
of moisture in, on, or adjacent to, electrical equipment, and includes partially protected
3. WET LOCATIONS —- Only luminaires marked “SUITABLE FOR WET LOCATIONS” are
intended to be installed in wet locations. A wet location is a location in which water or other
liquids may drip, splash or flow on or against electrical equipment. A luminaire marked
“SUITABLE FOR WET LOCATIONS” may be additionally marked as specified below:
a. Covered Ceiling Mount Only — A wet locations luminaire marked “COVERED
CEILING MOUNT ONLY” is intended for locations such as a vehicle washing area
where the luminaire will not be subjected to water and precipitation from the back side. A
ceiling mounted luminaire not identified for covered ceiling mount only is suitable for
mounting in locations where it may be subjected to precipitation from the back side, such
as under a metal grate-type catwalk.
b. Less Than 1.2 M (4 Feet) Above Ground Level — A wet locations wall or post
mounted luminaire may be installed within 1.2 m (4 feet) of ground level if it is marked
“SUITABLE FOR MOUNTING WITHIN 1.2 M (4 FEET) OF GROUND.” luminaires with
this marking are intended to be subjected to water from lawn and garden sprinkler
systems, but are not intended to be installed at or below ground level where they may be
subjected to immersion in water.
Exception: A luminaire with an integral post (bollard type luminaire) needs to be so
c. Below Ground Level — A wet locations recessed luminaire may be installed at or
below ground level if it’s marked “SUITABLE FOR GROUND-MOUNTED RECESSED.”
A luminaire with this marking is intended to be subjected to infrequent immersion under
water which may occur because of heavy precipitation. The luminaire is provided with
instructions for its proper installation.