Quality Control: Commercial Water Heater & Recirculation Pump Power Cord Exposure
Updated: Mar 1, 2022
During a quality control survey performed on a commercial clinic, our team observed an anomaly and fire hazard risk with a water heater and circulation pump configuration. It was noticed that although the water heater power connection ran through a disconnect switch and liquid-tight flex cable, the recirculation pump used plug-and-play power cord connected to nearby dedicated duplex outlet. See the closeup schematic showing location of the pump.
Because the outlet was installed long before the plumbing contractor mounted the equipment and in/out flow pipes, the pump's power cord was simply stretched and laid out haphazardly without accounting for the possible proximity of hot surfaces. At the time of the pump installation, the water heater had not yet been turned-on and it's likely that the in/out pipes had not been welded. See the image below.
However, once the water heater was commissioned, the surface temperature of the out-flow pipes naturally became elevated as it pumped out hot water, causing the unsecured recirculation power cord to become a fire hazard. Perhaps it is an obvious error upon closer look, but this issue only became apparent after a thorough thermograms analysis was performed back at the office. A likely explanation is that this type of issue is not very common and can be easily glossed over by untrained eye.
CATCHING THE FIRE HAZARD
Although Aglow's scope of work was limited to only inspecting electrical components and systems, our team is trained to look for broader risks such as; environmental factors, ergonomics of human interaction and behavior with equipment, installation errors/hazards, building and/or layout related risks, and interactions between operators and machinery. In this case, our thermogram analysis looked at the entire equipment heat signature, not just the power components and identified that the recirculation pump power cord was in direct contact with a very hot surface.
It became obvious that the causation of the temperature elevation was because the surface of the pipe was on the return side, in other words, the heated water. See thermograms below.
COURSE OF ACTION
A fault report bulletin was issued to the general contractor and the owner of the risk identified and potential course of actions was recommended. Proposed solutions included:
Option 1. Relocate the duplex outlet closer to the pump and secure its cord to the wall or other structure.
Option 2. Zip-tie the power the small whip of the power cord to the equipment so that it doesn't come in contact with the pipes.
Option 3. Replace the power cord with direct power through a flex conduit that is tied-in with a simple wall toggle switch for emergency power-off.
Environment and machinery ergonomics must always be considered when designing, installing, and adapting equipment on the field. In this case, a power cord stretched over the surface of a hot water pipe would most likely have caused a fire hazard or could have caused the equipment to go into catastrophic failure first. It's impossible to meet the outsize expectation of completing projects with error-free results using only human resources and experience. A realistic success marker is not just completing a project in the least amount of time, but rather by providing personnel with non-intrusive augmented tools to ensure maximum system performance under the circumstances.