Relevant Electrical Concepts
Electricians are taught about human safety. You are not asking about human safety. You are asking about transistor safety. That involves electrical concepts rarely taught to electricians.
For example, what defines low impedance? Electricians are taught about things related to resistance (ie wire thickness). You are asking about a completely different concept involving impedance (ie wire length).
In any factility that cannot have damage, earthing of a 'whole house' protector is routine. Your telco's $multi-million switching computer (in a CO) connects to wires exposed all over town. It suffers about 100 surges per storm. How often is your town without phone service for four day? Never? Exactly. Because they do not use protectors you are discussing. Instead they use a 'whole house' solution. And, more important, upgrade what defines all protection. Single point earth ground. An 'art' that should be most of your questions.
A typical homeowner might suffer a potentially destructive surge once every seven years. However, a least expensive solution is also the only one routinely used in every telco CO. Those are obtained from the many more responsible manufacturers. And is the best answer for your questions.
Ignore joules. Those are protectors from transients that typically do no damage. The relevant parameter is amperes. A mimimally sized 'whole house' protector must connect 50,000 amps harmlessly to earth - and not fail. Those provided by 'more responsible' manufacturers. Typically costs about $1 per protected appliance.
True for all protectors. And not always understood by electricians. A protector is only as effective as its earth ground.