One of the biggest challenges we've faced involves code upgrades. For example, when we have a building where a conduit was used for grounding. In older commercial buildings, a metal conduit was often used as a grounding conductor. This practice was more common in older electrical systems where dedicated grounding conductors were not always required by code. While this method was acceptable in the past, modern electrical codes generally require dedicated grounding conductors within the conduit, separate from the power conductors. This is because relying solely on the conduit for grounding can introduce potential risks, such as corrosion, disconnections, and limited capacity. That's why when we retrofit an older commercial building with a modern HVAC, present-day code dictates we must upgrade everything we touch, including venting, gas, and make-up air, which is what we do.