And This Is Why We Do FMEAs

A couple months ago my hot tub went on the fritz. Of course it did it during the coldest part of January, so I had to drain it because I didn't think I could get it repaired in time to prevent damage from all that water freezing. I suspect what may have happened is that the heater shorted, but I don't have much data to support it.

When I went to check on the hot tub that fateful day, I found that it had blown the breaker. So I reset it and then went back outside to see if I could diagnose the reason for the breaker tripping. I ran all the jets for about 30 seconds with no problems, but when I turned them off I could smell something electrically hot. Then I turned the jets back on and went by the control area to sniff around and determine the root cause. After about 20 seconds, I got a fireworks show and the breaker tripped again. When I opened up the control panel, this is what I saw. There was a reason for such big fireworks!


So the moral of this story is: this is why engineers do Failure Modes and Effects Analysis. What happens if the heater shorts? Will it trip the breaker? Start a fire? Electrocute whoever is sitting in the hot tub at the time? Much as I hate doing them, I will admit that sometimes there is a good reason to do one. I just wish doing them wasn't so painful.