Do gas discharge tubes used e.g. for surge protection have a polarity, i.e., do they protect in both directions (i.e., depending which wire is hit, or if it is a positive/negative lightnings?
The symbol (see below, from Wikipedia) has a dot that suggests some asymmetry. Electrons should be able to jump in any direction, but how are the positive/negative electrodes engineered to facilitate/stand the discharges?
Best Answer
Photo attribution:
By Ceinturion 17:47, 19 August 2007 (UTC) - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2587926
Small dot indicates "gas-filled". Likely at sub-atmosphere pressure. Its position within the schematic symbol doesn't suggest polarity.
These devices may include thoriated electrodes to reduce striking voltage.
So for this example: it is bipolar....strikes with either polarity.