Lightning protection for outdoor device/post?

[thewire]

We will have devices installed outdoor on covered or open area on a 4-5' high post (stainless steel). It will be powered via POE from a poe switch located approximately 5' away in another cabinet.

I think we should have ground rod installed at base of the post for protection of the POE powered device and the downstream equipment? This is a public interface device.

the post will be mounted with 7" anchor bolt (4) into structure concrete


Device is just a card reader

Basically you can say it's a parking meter (minus coins) just contactless reader ...about the same height

 

[user 100]

We will have devices installed outdoor on covered or open area on a 4-5' high post (stainless steel). It will be powered via POE from a poe switch located approximately 5' away in another cabinet.

I think we should have ground rod installed at base of the post for protection of the POE powered device and the downstream equipment? This is a public interface device.

the post will be mounted with 7" anchor bolt (4) into structure concrete


Device is just a card reader

Basically you can say it's a parking meter (minus coins) just contactless reader ...about the same height

Do you really mean lightning protection?

In short, adding a rod isn't going to do a thing here to advance equipment protection - the concrete (with all that rebar) that the post is going to be anchored to is a fine electrode all by itself.

 

[winnie]

An isolated ground rod can actually make things worse in terms of lightning protection.

You have the separate issue of what happens if lightning strikes the structure itself, and what happens if lightning strikes nearby.

A nearby strike causes current flow in the earth, and an electrode in contact with the earth can conduct that current _into_ a structure. This is why you are required to bond together all of the grounding electrodes at a structure; what you don't want is lightning currents flowing in via one electrode, through equipment or people, and then out via another electrode.

In your case you have a small structure which is already in contact with the earth, so it is already (inadvertently) grounded. This structure has wire coming to it, presumably from another structure with its own grounding. A nearby strike could cause a significant voltage difference between the cabinet and the wiring, causing damage.

In my (not professional and not qualified by training) opinion, lighting protection would require bonding between the cabinet and the supplying structure, and surge protection for the equipment in the cabinet.

On the other hand, the cost of providing bonding between the structures and surge protection for the equipment in the cabinet might exceed the cost of the equipment.

-Jon

 

[thewire]

thanks guys. Yes I meant lightning protection "

Since the only cable coming out of the post is a CAT6. I think I will be suggesting having a surge supressor in front of the switch and have it located at the cabinet just case the small post got hit from lightning.