Light Emitting Diode (LED) Frequently Asked Questions (FAQ)
Here are a number of frequently asked questions concerning retrofitting street lights with LEDs. (remember to cite your sources and sign/timestamp your answer)
LEDs
- What does an LED traffic light look like? (picture)
An LED traffic light looks very similar to a regular traffic light. It still gets the job done and is actually brighter. An LED is actually very small and therefore the traffic light is made up of a bunch of smaller lights, this is apparent when you look closely. A link to pictures is posted below. http://www.china-led-manufacturer.com/china/led-traffic-light.htm --Susan 14:40, 16 September 2007 (PDT)
- How does an LED work?
- What is a diode?
- What is a p/n junction?
- What does solid state mean?
- What are the common elements that make up an LED?
- How are LEDs made?
Efficiency and Lifetime
- How efficient is an LED compared to a CFL or an incandescent bulb?
- What are the wattages of a normal incandescent light compared to an LED?
- How long do LED bulbs last? (e.g. what is the estimated lifetime of an LED?)
- How long do standard incandescent bulbs in street lights last?
- How many incandescent bulbs (and light bulb changes) do you need to last as long as a single LED?
LED Retrofits
- How do you replace a normal incandescent street light with LEDs?
- What colors are LEDs available in commercially?
- Who manufacturers LEDs for use in traffic lights? (link to web pages)
- Are any large cities using LED traffic lights? (Name at least 3 with articles -- about half the cities in PA have done it)
Do LEDs save money (show your work)
- What are the major variables in determining savings?
- How much money is saved over the lifetime for switching out a red light with an LED?
- What is the payback time and return on investment for red LEDs?
- How much money is saved over the lifetime for switching out a yellow light with an LED?
- What is the payback time and return on investment for yellow LEDs?
- How much money is saved over the lifetime for switching out a green light with an LED?
- What is the payback time and return on investment green LEDs?
- How much money is saved over the lifetime for switching out a walk/do not walk sign with an LED?
- What is the payback time and return on investment for white man LEDs?
- What is the payback time and return on investment for red hand LEDs?
- How much money does it cost to make the switch (labor + materials)?
LEDs and the environment
- If the street lights are running on coal-fired electricity - how much carbon dioxide emissions are prevented by switching to LEDs?
- How much pollution is prevented switching an average intersection to LEDs? (list all and amounts)
Any other questions
- Is there any reason not to switch to LEDs?
- Why hasn't everyone already done this?