@Attie, "why" because for a small business, with only 4 employees (owner, secretary, ladder-climber, and me) that is non-electronics service provider, making electronics is not what we do. We make electronics to make our real job easier/possible/reliable. Pre-loaded parts are really the only financially realistic way to get hardware built, as a small business.

@MOSFET I wish had that luxury. Every intern we hire says stuff like that. I did too originally. It really is amazing what you can accomplish with these limitation. We are a small company (4 employees) and its not an electronics firm. We just make equipment for internal use, that we can't buy, or what you can buy is too failure prone.

Yes, the board house has a N-fet 150v part, and that is my current design, but the 5V to power it is added complexity I was trying to avoid. I'm also very small power budgets (like can't use a Diode). My currents are low (fet gate drive) and my switching frequency is in DAYS. I'm running the LED at 5mA. Also as stated in above, I'm expecting 90v transients so I want a 120v or 150v part. The Part is the 'B' version so a CTR of 130-260, but I'm just using it as a switch to the current gain isn't important as I don't wan to burn much current on the transistor side either. Thanks

@JonathanS. long incoming transmission line, so think static lightning charges, and other outdoor hazards. Directly connected would be the Gate of a P-fet, but with added protection of the Fet pins, so that any over-volt would pass by and on to this control element. Thus the Control (this Optocoupler) can be exposed to ~90v

Also the case of the cap is used as a contact for the complete circut. So the ESR of the cap wpuld be unaffected, AlO on the surface would only add to the incoming wire resistance. Aluminium Oxide forma

An axial cap would only expose the one lead to the contact, This is not how a decoupling cap is conected. The circut, and the cap lead must connect to the contact.