When you wire a panel surge device, do you connect to the terminals of an existing two-pole breaker? Does the Code address this?
I got a call to check-out some electrical issues brought up by a home inspector. One issue was two wires to a breaker's terminals and I found the additional wires to be the two "hot" wires from the supressor. There is not room in the panel for a two-pole breaker dedicated to the supressor. Since the supressor is not a "load", I wouldn't think that it would matter if it's terminated on a breaker's load terminals along with the actual load, as long as it's a 15 amp breaker because the supressors wires look to be 14 AWG. . Hopefully, someone will say if it's a code issue.
A separate matter is that the breaker the supressor is connected to is the main breaker in a GE split bus-panel, so it's really the unprotected line terminals on the breaker. If someone chimes in and says it's OK to connect to a branch circuit breaker, I will move the wires to 2 15 amp breakers. If not, I will remove the supressor. In any event it's coming off of the main.
Don

Some breakers, such as Square D QO, are designed to accept 2 conductors of equal size. Most are not. I always give the TVSS its own breaker, most say to use a breaker 30 amp or less. Device wiring is allowed to be smaller than branch circuit wiring due to the short length. One option is to pigtail the TVSS with a 15,20,or 30 Double Pole, but make sure the device is rated for that breaker.