LED Street Light Conversion Project

Frequently Asked Questions

What street lights are being converted?

Many of the “cobrahead” style lights owned by PPL are being converted from high-pressure sodium (HPS) bulbs to LED.Cobrahead Street Light The Borough has approximately 1,095 cobrahead lights within its limits. As of May 2019, 379 HPS lights were converted to LED. In October of 2021, Council approved the conversion of 506 more street lights.

The cobrahead lamps that will be converted are 10 years old or older. Cobrahead lights with underground electric supply or those which otherwise do not meet the criteria for no upfront costs and no monthly cost increase will not be converted.

The decorative lights on High and Hanover Streets are not being converted. 
Why switch to LEDs?

There are various reasons the Borough is participating in PPL’s conversion program:

  • LED lights provide more focused lighting and they appear whiter and brighter than HPS. The Borough receives requests from concerned residents for lighting improvements, citing safety concerns.
  • LED lighting emits equivalent useful lighting while significantly reducing the overall output of lumens. The kilowatt hours will be reduced to 53%-61% of current usage.
  • LED lighting reduces many negative lighting impacts, including backlight, uplight, and glare. Wasted light, light trespass, and light pollution are more manageable with proper LED lighting.
  • The LED lights provide a cost-savings to the Borough. They are more reliable, require less maintenance, and have a lifespan that extends well past that of the HPS lights. They also consume much less energy than HPS lights. Currently, the Borough projects an approximate yearly savings of $5,000 for the 379 LED lights already installed.
  • Enhanced lighting benefits public safety, including law enforcement, pedestrian safety, and motorist visibility, especially on wet roads or during inclement weather.
LED Lighting vs HPS Lighting
How much will this cost the Borough?
PPL is upgrading the lights at no cost to the Borough.
What color temperature are the LED lights going to be?

PPL is installing LEDs with a CCT of 4000K.

But isn't 4000K bad? The American Medical Association recommends 3000K or lower?

In 2016, the AMA did provide a report that recommended fixtures with a CCT of 3000K or lower for roadway installations. Their concerns focus on the short-wavelength emission, or blue light, from LED sources as possibly related to glare, melatonin suppression, and circadian disruption. However, the focus on just the CCT ignores other factors such as amount, duration, and timing of light exposure.

LED lights do contain more blue light than HPS lights. However, LEDs have a reduced lumen output when compared to HPS (HPS 9,500 lumen output is equivalent to an LED 4,900 lumen output). This reduced lumen output is thought to significantly offset this inequality.

Research from the Federal Highway Administration shows that exposure to artificial lighting of 2500 lux of white light for two to four hours can suppress melatonin. The light levels of residential street lighting systems rarely exceed 10 lux outdoors. Indoors and behind curtains, the levels are likely even lower. For comparison, blue light exposure from electronic devices such as televisions, cell phones, tablets, and computers is about 15-30 lux.

Could PPL provide us with 3000K lights if the Borough asks?

No. PPL’s conversion option was limited to the replacement of existing lights on the same poles with comparable LED lighting at 4000K.

I had a light installed by my house and it is too bright. Do I have any options?

As part of the agreement, PPL has agreed to install shields on the lights and make adjustments when possible, upon request at locations where the LED lights are perceived as problematic. It is imperative that requests include the direction(s) of primary concern.

If you would like to request a shield or need more information, you can contact either Rick Frieben, Engineering Technician (rfrieben@carlislepa.org) or Mark Malarich, Borough Engineer (mmalarich@carlislepa.org).

Carlisle Boorugh 53 West South Street 717-249-4422 Mon-Fri: 7:30 AM - 4:30 PM