Stay within the specifications

This is another case of my having a discussion with a fellow worker and wanting to write down the idea before I forget it again.

We were talking about specifications for our products. We usually specify that the part will work within a certain temperature range and supplied with a certain range of voltages. We sometimes need to specify other things like a humidity range, too. For our software, we specify that it should be used on certain versions of the operating system or with certain versions of Java (the language, not the island or the beverage). We are always getting calls from customers that complain.

Say we specify an operating voltage as not to exceed, say, 12 Volts. The customer calls to say they've always had good luck running them at, say, 14 Volts - until now! Now, they've run into a series of problems when they run them at 14 Volts and they need to fix it NOW! Why can't they use it at 14 Volts? It always worked before.

Then I tell them my story about the guy who always drove his car 10 miles an hour over the speed limit. He did this for years. Then one day, he went through a speed trap and the policeman who was running the trap wouldn't give him a warning but wrote out a ticket.

That's what it means to run equipment out of its specifications.