Two copper leads to a glass enclosure 1/4 " x 1 1/4 ". Inside one lead goes to the long side of an inverted "J" 1/4" x and the other lead adjacent and touching the the other. It comes from a simple 12 V. power supply, one transformer and one diode bridge rectifier and itself. Is it a neon tube or a limiting switch? It has the markings " ECG 202 P312 2HAV " on the glass. I am interested in finding it's specifications. Thank you

 

Can you post a photo of it?

Neon bulbs generally have a breakdown voltage somewhere in the vicinity of around 55v (give or take) and are pretty low-current. If forced to carry a lot of current, they will burn out in a hurry.

Sylvania became ECG, and ECG was bought out by NTE Inc.
I regard NTE Inc. as a "vulture" electronics distributor, charging enormously inflated prices for obsolete components. They have a cross-reference that naturally only goes one way; to their part numbers. Their prices range from the exorbitant to absurd.

 

Reed switch?

 

Self resetting thermal circuit breaker??

 

If there is a coil underneath, or very near by, a reed switch is a fair guess. Reed switches are not known for current carrying capability; if subjected to more than 100mA or so, they will burn out in a hurry.

Self-resetting thermal circuit breaker is a better bet.

I'm thinking more like a one-time-use fuse. These are frequently soldered to cheap supply boards.

 

I regard NTE Inc. as a "vulture" electronics distributor, charging enormously inflated prices for obsolete components. They have a cross-reference that naturally only goes one way; to their part numbers. Their prices range from the exorbitant to absurd.

We joke about NTE that eventually, they will get down to one part number that will replace anything!
Ever notice how any one of THEIR part numbers can replace up to 20 or more standard manufacturer numbers?