PEX water tubing is being stored and installed where it will see direct sunlight for an extended period. What does the code require regarding that exposure?
- APEX may be exposed to sunlight indefinitely, because the chlorine resistance rating printed on the tubing covers ultraviolet exposure as well
Chlorine resistance ratings are printed right on the tubing, so borrowing them for another exposure is an easy step to take. They describe performance in hot chlorinated water and say nothing about ultraviolet aging.
- BPEX may be exposed to sunlight if it is coated with a latex primer that blocks ultraviolet light before the wall is closed
Paint really is a UV barrier on other materials, which is what makes this sound workable. It is not a listed protection method for PEX and no manufacturer's instruction offers it, so covering the tubing is the answer.
- CSunlight has no effect on PEX, and only sustained temperatures above 180 degrees F will shorten the service life of the tubing in a hot water distribution line
Temperature limits are real and the 180 degree figure is close to a genuine rating, which is what sells this. Ultraviolet damage occurs at ordinary ambient temperature, which is why the limit is stated in months of exposure.
- PEX must be protected from ultraviolet exposure, and any exposure is limited to what the manufacturer's installation instructions and listing permit
Why D is correct
Materials must be installed according to their listing and the manufacturer's instructions, and PEX listings carry a stated ultraviolet exposure limit. Protecting the tubing from sunlight during storage and keeping cumulative exposure inside that stated limit is what keeps the installation compliant.
What this question is testing
The item tests whether the candidate understands that listing and manufacturer's instructions are enforceable code requirements, and knows the specific vulnerability of PEX to ultraviolet exposure.
On the job
The damage is invisible. A coil that baked on a jobsite for a summer looks fine, installs fine and passes a pressure test, then splits in a wall two winters later. Practical habits: keep coils in the carton or under cover, do not use the sun-faded outer wraps of a coil, and note that supply houses sometimes store tubing outdoors. If a skylight well or a garage will leave tubing permanently exposed, sleeve it or reroute.
Memory technique
Sun ages PEX. Keep it in the box until it is in the wall.
Exam tip
When an option says according to the manufacturer's instructions and the listing, it is usually right for plastics.
Where to look it up
Chapter 3 installation-of-materials provisions read with the PEX entries in the Chapter 6 water distribution material tables. UPC jurisdictions state their own plastic piping restrictions, so verify against your adopted code.