You will see best performance when SurgePure modules are placed on the down stream sub-panels for a complete cascading grid of protection. Having layered protection throughout a facility is key to isolating nearby switching loads from digitally sensitive loads.
On average 75% of all 'in house' surges come from internally generated switching loads. Surge protection provides isolation of all inductive and capacitive loads from taking their toll on digitally sensitive loads on the same distribution panel.
When sizing the right surge protector for your application we need to keep a couple things in mind.
What is the cost of the equipment at risk?
What is the cost of being down per hour?
These factors will help determine what size of surge protector you should have on the main service entrance. Having a larger model with more surge capacity on the main service is wise when we have a lot at risk. SurgePure is there to close the gate on what is trying to get in.