Do breach and/or fire chances roll per damage or per hit?

It seems to me that weapons that do more damage in a single hit, tend to proc their breach or fire chance more often. Is this observation false or true?

How are Breach or Fire procs calculated?

Solution 1:

Each weapon has a specific chance of causing a fire or a breach. As it happens, weapons that do more damage tend to also have higher fire or breach chances.

The chances of each weapon causing a fire or a breach are summarised in a few tables on the unofficial wiki, grouped by weapon class. In these tables, Fire & Breach chances are either given in percentage form or on a scale of 1-10, with 1 being a 10% chance and 10 being a 100% chance to cause a fire or breach. (Empty cells denote no chance of fire/breach.)

As promised, I conducted an experiment to determine whether the fire/breach chances are rolled per hit or per volley. To do this, I had to modify the game files. I created a ship that carried a laser weapon that shot 5 times, with each shot doing 0 damage. It also had a 2 for fire chance. The ship also carried an ion weapon to disable both the enemy weapons, to prevent enemy attacks from interrupting the experiment, and the enemy piloting, to ensure all attacks hit and to prevent them from jumping away.

The results can be found in this table. Columns titled 1 through 5 are the results from each shot of the volley; H denotes a hit and F denotes a hit that caused a fire. I did not count any hits after the a fire was caused. P represents the expected amount of fires if the chance is for each volley, and Q represents the expected amount of fires if the chance is for each shot. The ? field notes whether P or Q was closer to the experimental amount of fires.

From these data, I conclude that the fire (and presumably breach) chance rolls are for each weapon hit, so a weapon that hits 3 times with a fire chance of 1 will have 3 rolls of 10% each for causing fire.