Grounded ??

I am working on an outdoor PLC panel that is having issues with damaged PLC modules among other things. The first thing I noticed is that the panel has no incoming service ground wire. In most panels I've worked with in the past, the site ground ran right into the control panel to a common bus (after connecting to the neutral in the service disconnect) and all grounding/bonding wires were connected directly to that bus. The attached sketch shows the layout. Here are some details. (A) 3-phase power with neutral runs to disconnect where neutral and ground wires are connected. 3 phases and neutral continue to meter and then into panel. Ground wire ends at the disconnect. Control panel ground is through the rigid steel conduit connections only. (B) "Grounding" wires in the PLC panel are connected anywhere and everywhere to the backplate. Comments, please from a code point-of-view and from a "sensitive equipment protection" point-of-view. Many thanks!!

Any Panel connected to power must have a ground connection, this ground connection has to be same size as cable (mostly they are in the same cable or the shield is used.
It is not allowed to connect Neutral and ground by you, only the utility is doing this after making sure the ground is oke and low enough.
All ground wires should be connected to one point only, to prevent ground loops.
The door must have a ground connection too.

There is an exception to this rule when the voltage is lower as 50 Volt it is a good practice to do, however not mandatory. So when the power supply is outside the cabinet (it never is).

In our province it is code that the neutral be bonded at the first point of disconnect. It is also code that rigid steele conduit may be used as a bonding conductor so long as it is not made of stainless steel, burried in earth or masonry slabs in contact with earth and there are a few more exceptions to the rule. However leagal it may be its just ugly and inevitable to fail eventually as locknuts and such corrode. If the size of conduit permits you may be able to simply pull a ground wire to bond your panel to ground or run a piece of conduit to the disconnect to attach to the ground electrode if the pipe is already at capacity.

Does Nova Scotia have palm trees?

We would have if you send us up some palm tree seeds!

you have a blown plc and bad grounding job...is it an AllenBradley and the cause brings you back to grounding ? (When you don't have causes, blame the grounding!!!)

i would make the ground to respect the code but i would also suggest a surge protrection system because and/or if possible, replacing the plc by a 24vdc model powered thru a 120-24vdc powersupply to be the first point to blow in case of incomming power issue. Usually an industrial 120-24v ps will handle some kind of surge and voltage fluctuation way better than a 120v AB plc

I am working on an outdoor PLC panel that is having issues with damaged PLC modules among other things.

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I would install a surge arrestor on the control panel power to shunt incoming power surges and spikes to ground (after making sure you do have a low-resistance path to the earth).

Sounds like circulating ground currents. This happens when there is a potential difference between locations with one location being the ground grid.