I've ordered a Siemens FS140 Whole House Surge Protector that I will install myself.
The instructions say to keep the leads as short as possible and straight as possible. I have an open square d slot farther away from where I want the FS140, but have a couple of 20 amp breakers already installed near where I'd want it. They feed the kitchen counters.
Is there a disadvantage to connecting the FS140 to the existing breakers (with pigtails) or does it really need its own breakers?
Update:
Response to moving it — my two free slots are at the very top of the panel. At the bottom are 2 x 30amp solar disconnects and then 2 x 20amp tied kitchen breakers. I'm realizing now my bigger problem is the conduit underneath and beside which won't let me fasten the device to the wall. Maybe I should just put it the top, which makes it harder to see, but you can't win all the time!
Update:
Thank you for the advice. I ended up shifting breakers up to make room for the SPD breaker near the middle (where the power comes in). I couldn't get it quite next to the middle because the bonding bar was in the way, so I ended up a slot or two higher, but this allowed the wires to be straight.
I was also worried about the 1.25" OD conduit on the right being in the way, but had forgotten there is already a 1" offset built into the SPD.
Best Answer
If the options
are mutually exclusive, option A) is more important for the surge suppression, since possible capacitive or inductive couplings are minimzed.
The breaker is needed if the SPD is damaged or has been loaded with too much surge energy resulting in a long term low resistance - e.g. after a near lightning hit. The normal circuit breakers (e.g. 20A) are much too slow to cut the surge current, which may be in the range of hundreds or thousands of Ampere, but will only flow for microseconds.
A SPD should be connected as close as possible to the incoming lines (power provider) of the breaker panel or main panel with as short connections as possible. At the same time, these wires should be "lonely" wires, i.e. all other wires should have a big distance to those SPD connection wires again to minimize any couplings.