Outdoor Panels, AFCI Breakers, and Environmental Realities

[jar546]

I came across something interesting that’s been popping up in some parts of Colorado, and it raises a good discussion point about the difference between something that’s code-compliant and something that’s field-proven.

Inspectors out there are reporting nuisance tripping on AFCI breakers when the main service panel is installed outdoors. Ever since the 2020 NEC added the requirement in 230.85 for a readily accessible disconnect outside, builders have started placing the entire load center on the exterior wall. It meets code, no question about that, but it’s starting to expose another problem.

All breakers, including AFCIs and GFCIs, are tested and calibrated at an ambient temperature of around 104°F during UL certification. That’s fine in a controlled environment, but not when that same panel is baking in the sun. A metal cabinet mounted on a west or south wall can hit 120–140°F inside, and that’s before any load heat from the breakers themselves. AFCIs have electronic components on their circuit boards, and those electronics don’t love constant high heat, cold, or humidity swings.

Down here in South Florida, we see the opposite challenge: constant heat, humidity near 100 percent, and plenty of condensation. Even though our panels are usually indoors, any electrical equipment sitting in that kind of environment ages faster. So it makes sense that in Colorado, where panels are sitting outside in the sun and cold, those same AFCIs are tripping or failing sooner. It’s not a defect in the product; it’s the environment pushing the limits of how it was designed and tested.

This is one of those cases where the installation meets code, but we know it’s going to be a problem in the real world. So the question is, how do we as officials, inspectors, and installers manage something that’s technically compliant but predictably troublesome? Should there be guidance on panel placement, shading, or environmental derating? Or is this something that needs to come from the manufacturers and code panels in the next cycle?

Curious how others are seeing this play out in different climates, especially where outdoor panels have become standard practice.

 

[BN4537]

We had a local amendment requiring an exterior disconnect for years before it came into the NEC. Almost no one will mount a full-blown panel outside anymore because of the issue you stated. In the end, the callbacks taught the contractors faster than if we could have if we got involved.

In my jurisdiction, I warn people if something code compliant will cause them problems later, and then pass the inspection. I also might mention it during our continuing education classes.

 

[ICE]

It’s not a defect in the product; it’s the environment pushing the limits of how it was designed and tested.

Clearly there is a product that fails in the environment that it was intended to withstand. How is that not a defective product?
Consider GFCI receptacles as an example. Standard GFCI receptacles are not permitted in outdoor locations because they will not withstand the environment. Therefor a GFCI receptacle that is rated Weather Resistant is required as that receptacle can withstand the environment.

I find it odd that this is unique to Colorado and apparently Kansas when California has not experienced this at all.... at least not that I am aware of.

I would like more details such as which brands are involved, which product lines are involved, which NRTL evaluated the products.

Lastly I point out that a Listing by an NRTL means that the product was evaluated per a particular Standard. The issue might stem from that point.