My small office has a 20A breaker and we have to run a space heater in the winter or else we freeze to death. Whenever someone turns on the coffee maker, the office circuit breaker trips and everyone's computers are down for 10 minutes while someone goes and resets the breaker. We've tried implementing a policy of shutting off the space heater before starting the coffee maker, but it's too easy for people to forget.
I plugged both devices into a power strip rated at 15 amps, and I assumed since it had a reset switch, it would actually trip at 15A. Much to my surprise, the office breaker still tripped. I also tried a different 15A power strip with the same results.
I then plugged the power strip into a Kill-A-Watt meter and it measured over 22A with the coffee maker and space heater both running, before I unplugged everything. My best guess is that both the office breaker and the power strip have time-delay breakers, but the office breaker is on a shorter delay. Another theory is that the power strips are manufactured to very loose tolerances and will only trip if the current far exceeds 15A.
So my questions are:
- Why isn't the 15A power strip tripping? Should it even have a time delay?
- If we just need to buy a better power strip, is there an easy (and safe) way to test at what current a power strip will trip, aside from plugging a bunch of stuff in and potentially tripping the office breaker instead? (Edit: I think I found the answer to this one.)
- If all else fails, what can I install between the wall and the appliances which will trip the space heater and coffee maker before the office breaker trips?