Separate Structure - Grounding Electrode?

[jcook980]

So that I can be sure I understand the responses to the "Separate Building-Minimum Feeder" post correctly (and a couple of other questions)...

I have a premanufactured, skid mounted, chemical metering pump and chemical storage tank installed inside CMU "walls" with a open steel grate "roof" and a chain link "door" for vandal protection.

The skid is feed from an adjacent building's lighting panel with a single 15A 120V circuit and EGC. The circuit feeds the control panel which has a circuit breaker to disconnect the unit inside the control panel door.

No grounding electrode is needed, correct? (250.32 (A) Exception)

Does the chain link door and steel grate roof require grounding? I don't feel they meet the requirements of 250.4 (A) (4) because they are "not likely to become energized".

Is an external disconnect switch required because the means of disconnection is not readily appearent inside the local control panel?

Thanks!

Jim

 

[hforney]

Re: Separate Structure - Grounding Electrode?

Jim I am the original poster of "Separate Building-Minimum Feeder". My understanding is that you do not need a ground rod. Don't take my opinion as the gospel truth! It was nice to see how someone else can feed from another's post. I am fortunate to be able to spend about an hour a day on this forum. I have been doing this for the past several months and it has truly helped me to learn and to also realize how little I really know. Back to your question,,,,,,,

250.32 Two or More Buildings or Structures Supplied from a Common Service.
Exception: A grounding electrode at separate buildings or structures shall not be required where only one branch circuit supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the conductive non?current-carrying parts of all equipment.

 

[jcook980]

Re: Separate Structure - Grounding Electrode?

hforney,

Thanks for replying. Yeah, your post seemed to trigger a much expanded discussion. My questions were posted separately to keep that discussion on track.

I don't think a separate grounding electrode is needed because it fits the Exception. I would like to know whether or not the steel grate "roof" and chain link "door" need to be grounded and if a disconnect switch is needed outside the control panel.

Jim

 

[hurk27]

Re: Separate Structure - Grounding Electrode?

I would think that as far as the disconnect goes a single pole switch just inside the door would meet the requirment, but being located in a control panel I wouldn't think that could be defined as readily accessible. as one would have to know where it was. I used a red handle switch to mark it as the disconect and installed a plate just outside the door telling where it is located.
225.32 Exception 1 does allow for it to be located elsewhere.

225.32 Location.
The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors . For the purposes of this section, the requirements in 230.6 shall be permitted to be utilized.

Exception No. 1: For installations under single management, where documented safe switching procedures are established and maintained for disconnection, and where the installation is monitored by qualified individuals, the disconnecting means shall be permitted to be located elsewhere on the premises.