To make sure certain piping designed to bring hot and cold water into a home or building isn’t too close to certain types of lighting, electrical and plumbing contractors working on the same projects can do some preplanning.

The Plastics Pipe Institute Inc. (PPI), Irving, Texas, released the technical document, “Potential Effects of Artificial Lighting on Crosslinked Polyethylene (PEX) Pipe and Tubing and Recommended Installation Practices,” which provides recommended installation practices for PEX piping exposed to indoor artificial lighting.

PEX piping may be adversely affected by ultraviolet (UV) emissions from certain artificial light sources, according to PPI. Fluorescent lights, either tubular versions or single-envelope compact fluorescent lamps (CFLs), are of most concern in residential and commercial applications, as these lights have the highest component of UV emissions.

LED lights, on the other hand, have little-to-no UV component in their spectrum, said Lance MacNevin, director of engineering for PPI’s building and construction division.

“One of the interesting parts about this publication is it all started about seven or eight years ago when LED lighting was still kind of new on the scene for both residential and commercial applications,” MacNevin said. “Although people had a pretty good feel for what the effects of other kinds of more historical artificial lighting would be on PEX piping, there were concerns about any effects from LED lighting.”

However, PPI found through its research that LED lights are the most efficient, meaning most of their power goes to visible light, he said. In most cases, LED lights emit the least amount of UVA and UVB wavelengths, unless they are particularly designed for applications like growing plants indoors.

For all residential and light commercial projects, PPI recommends that PEX pipe be installed at a setback distance of no less than 36 inches from direct incidence from artificial light sources (closer distances may be used for incandescent or LED lights). For industrial, manufacturing, warehousing and large commercial projects, the recommended setback distance is 30 feet.

In an ideal situation, there’s good communication among the trades and architects, including preconstruction meetings to find out if there are any concerns with what is planned, MacNevin said.

When it comes to lighting, particularly in industrial or commercial settings, in a lot of cases the location of the lighting is fixed based on where people are going to be sitting, if it’s an office, or where people are going to be working, if it’s on a factory floor, he said.

Even in a residential application, the architect will always have their favorite locations for the lighting based on how it’s interacting with the natural daylight and where people are going to be spending most of their time, MacNevin said.

“So in a lot of cases, it’s actually easier to move a pipe because, most of the time, the pipes are put behind the walls and nobody sees them and they’re not exposed to the lighting anyway,” he said. “It’s really more of a concern in industrial settings where you have exposed walls and the pipes are literally running on the side of the wall, clipped to the concrete wall, and you can see them.”

In cases where lighting is close to a pipe because a workstation is there, then the alternative is to protect the piping with a light-resistant wrapping or insulation, MacNevin said.

Plumbing contractors can also urge electrical contractors or the architect to select LED lighting, because it’s the older, traditional lighting that is the most harmful, he said.

“LED lighting is going to save you energy, it’s going to last longer¾and it’s going to make sure that you don’t do any UV damage to your pipes,” MacNevin said. “There could be other things inside a building too that can be damaged by UV light, like insulation coating on wiring.”

PPI released an earlier technical document detailing minimum distances that water pipes should be installed away from recessed lights up in ceilings, because “if they’re not LED, they can get really, really hot,” he said.

Illustrations courtesy of the Plastics Pipe Institute Inc.