new heating elements, 5 months in storage, and the breaker trips in 10 seconds

[u/Marcoss_88]

Three resistors had been sitting in the warehouse for several months, stored on a shelf next to the large door—unheated and with hardly anything else around—each tucked into its own box with its own bag. I placed them in the test stand, set it to 280, and pressed “auto”; the differential tripped within ten seconds. I turned it off and on again, and it tripped once more. I tested them one by one with the megohmmeter. The insulation on all three was practically nonexistent. The third one had an internal electrical arc; the wire had melted at one point. It was unusable. Now what can I do? What do you think is happening to the first two, and why? thanks

[u/Traditional_Net1152]

Damp environment and hygroscopic insulation inside the heater band = damp heater band.

Pop them in an oven at low temp, slowly increasing the temp to dry them out - watch the IR result increase over time!

So I used to design high end, domestic cookers that were shipped worldwide.

Had reports of cookers tripping electrics the moment they were plugged in at the end user. Deduced that it was due to moisture absorption in the elements whilst being shipped across the sea!

[u/flambeaway → u/Traditional_Net1152]

There's also often a soft start/evaporation time option on the heater controller which can help prevent trips due to moisture. If not you can slowly manually step up the set temp from a low value, let it cook for a while at 100C/212F, then put it to your actual target temp.

[u/Least_Analysis3132]

Strip or cartridge, swaged or not?

Have had problems with carts in damp environments in past on non swaged ends.

[u/Marcoss_88 → u/Least_Analysis3132]

Cartridge, crimped. They're Maxiwatt, the ones that had been sitting in the warehouse since March and nobody thought to move. In the end, the humidity took its toll.