I have been doing some research on this question and, while I found a number of questions here asking something similar, I don't quite get the side-by-side comparison I am looking for. Therefore I decided to ask my own version of the question.
I am designing a PCB which will eventually be fitted inside an aluminum enclosure and used outdoors exposed to the elements. A number of other devices are connected to this box through potentially long lengths of cable. Since this device will be exposed, I need to do my best to protect the PCB from nearby lightning strikes and similar events. The enclosure itself has a large copper ground lug to which an external earth ground strap is attached. The ground strap is connected to a large grounding rod pounded deep into the earth. My question pertains to the connection between the PCB and the aluminum enclosure.
There are two options that I would like to compare:
A heavy-duty wire about 3-6 inches long is soldered directly to a large earth ground pad on the PCB which connects to a copper pour covering the top and bottom layers of the board. This wire then connects to the back of one of the ground lug mounting screws with a large ring crimp connector.
Earth ground contact is made between the PCB and the aluminum enclosure using four large copper-plated mounting screws which secure the board in the box via the provided tapped mounting holes. The mounting holes/pads on the PCB are plated through and connect the PCB to earth ground by way of the copper-plated screws.
Which of these two options is preferred to ground the PCB and protect against EMI and/or large surge events? Obviously I am looking for the lowest-impedance option, which intuition would tell me is the one where the ground connection is made through the mounting screws, but there has been some discussion of the opposite being true.