The instructions state that a 2-pole 20 amp breaker is required. OK, fine.
Now here’s what I don’t understand; if the surge protector has its own breaker wired to hot, neutral, ground on both phases, how is it going to absorb a spike before other circuits?
The SPD protects the whole electrical panel from high voltage transient surges/spikes.
The Square D SPD uses multiple MOVs to protect the panel from high voltage surges/spikes transients. During a high voltage transient surge/spike event the MOVs limits the high voltage and absorbs or diverts the high current to ground. That is why the electrical service entrance neutral conductor connection to earth is so important. (The Grounding Electrode System.) The lower the grounding electrode resistance to earth soil the better. (Grounding electrode? Ground rod/s, metal main incoming water service piping, foundation footing concrete encased rebar.)
IEEE recommends 5 ohms or less.
It is very important where the electrician mounts, installs, the SPD to the outside of the electrical panel enclosure. (Do not install the SPD inside the panel.) Make sure he installs the 2 pole breaker for the SPD wire connections in the first two spaces below, near, the panel’s main breaker. Doesn’t mater which side just so it is in breaker spaces 1, 3 or 2, 4. The electrician more than likely will have to relocate a circuit/s load breaker/s to make room for the SPD 2 pole breaker. I would relocate the lighter load circuit/s breaker/s. The SPD connection wires must be kept short as possible without any sharp bends in the wires.
Square D HEPD50/HEPD80 SPD user guide and installation
NOTE:To enhance the performance of the HEPD50/HEPD80, twist and keep the conductor length as short as possible by trimming down the wires (do not loop or coil the wires and avoid sharp bends). Always connect the HEPD to the circuit breaker(s) found in the closest proximity. Increasing the HEPD conductor length will degrade its performance. https://download.schneider-electric.com/files?p_enDocType=User+guide&p_File_Name=NVE82551.pdf&am...
See page 4 and page 6, figure #3.
Why is keeping wires short so important?
Here is a great video on the why. https://www.youtube.com/watch?v=5Wb79cXmSlc
I attended a seminar a couple of years ago and seen the demonstration first hand.
Inches do matter.
Going from memory don’t you also have a sub panel for your audio equipment? If yes you should install an SPD on that panel as well.
For added protection of your audio equipment a Type 3 SPD should be installed to plug your audio equipment into. Make sure it has a minimum 1449 3rd edition listing. Newer Type 3 SPDs may have a 1449 4th edition listing. (Read the specs wording carefully. Minimum 1449 3rd edition listed).