Grounding for new Equipment Pad

[Smart $]

...

If you happen to create a new CEE and never had one to begin with, bring it to the existing grounding electrode system.

Call any new electrode an auxiliary electrode under 250.54 and connect it to the equipment ground bus in the new switchboard... and be done with it.

 

[Cow]

Expanding somewhat on my original question one of the feeders from this new Switchboard feeds a large chiller and auxiliary chiller pumps located on a new concrete pad some distance away.

I'm also trying to determine weather or not this new Chiller location requires a Grounding Electrode System per 250.32? Here's what I'm considering to make the determination:

1) Would this new chiller pad and equipment be considered a building or structure?

2) Is the circuit to the chiller considered a feeder ( or is this a branch circuit)? I would think its a branch circuit fed from the upstream switchboard since it only feeds a chiller starter. But what if inside the chiller enclosure there was other small distribution components that had further branch circuits to the individual chiller components?

If the answer is no to either of the above then I take it that a GES is not required? However would it be good practice to still install a ground rod, CEE, ground ring, etc....? I see lots of industrial designs that appear to have ground rings at locations like this weather its required or not.

When we wire chillers (and other equipment) separate but close to the service equipment we don't install or connect to a grounding electrode system. Of course this is dependent on whether you determine if it's a feeder or branch circuit, and how your inspector feels about calling it a separate building or structure.

 

[philly]

Call any new electrode an auxiliary electrode under 250.54 and connect it to the equipment ground bus in the new switchboard... and be done with it.

What would be the point of doing this if it serves no real purpose. One of the code reference books that I have says doing this is basically "worthless" as it does nothing. Perhaps for lightning dissipation or ground reference for sensitive electronics?

 

[Smart $]

What would be the point of doing this if it serves no real purpose. One of the code reference books that I have says doing this is basically "worthless" as it does nothing. Perhaps for lightning dissipation or ground reference for sensitive electronics?

Didn't you say new switchboard was being fed by the existing switchboard right next to it? Sorry I don't recall for certain and you're too post wordy to parse for answer (I'm being lazy at the moment).

Okay... here's the rub. Typical install with new electrodes you run GEC to adjacent switchboard and connect to existing GEC/GES. Then with feeder you run an EGC back to new switchboard. Other than a very slight chance of having a voltage gradient on the EGC system when experiencing a surge from nearby lightning strike (FWIW the possibility exists even when you do it "the other way") , the connections I suggest just forego the formality of running two wires. Instead you run one and they are all connected.

 

[Smart $]

What would be the point of doing this if it serves no real purpose. One of the code reference books that I have says doing this is basically "worthless" as it does nothing. Perhaps for lightning dissipation or ground reference for sensitive electronics?

PS: Your references are probably thinking about adding an auxiliary grounding electrode at the end of a say 15A branch circuit using a #14 EGC say some 100 ft. away from the panelboard.

I assume switchboard equipment requiring an 8' x 9' pad extension is not going to be powered by a measly 15A breaker and a #14 EGC, right?

 

[kwired]

Call any new electrode an auxiliary electrode under 250.54 and connect it to the equipment ground bus in the new switchboard... and be done with it.

If there is already an existing CEE I agree. If there presently is not a CEE and you create one, wouldn't it need to connect to the GES?

 

[Smart $]

If there is already an existing CEE I agree. If there presently is not a CEE and you create one, wouldn't it need to connect to the GES?

Auxiliary electrodes can be any of the qualifying types, including a CEE.

I do not recommend using a new CEE as an auxiliary electrode for say a 15A circuit. However, doing so with a pad-mounted switchboard fed by a pad-mount service switchboard immediately adjacent to it, I don't see a problem. I would probably take it to the degree of upsizing the supply feeder EGC the same size required for the service GEC.

 

[kwired]

Auxiliary electrodes can be any of the qualifying types, including a CEE.

I do not recommend using a new CEE as an auxiliary electrode for say a 15A circuit. However, doing so with a pad-mounted switchboard fed by a pad-mount service switchboard immediately adjacent to it, I don't see a problem. I would probably take it to the degree of upsizing the supply feeder EGC the same size required for the service GEC.

But if there were no CEE's before, doesn't adding one now mean you must use it as a grounding electrode on your grounding electrode system?

 

[philly]

I was finally able to make it to site and found that there are two existing ground test wells w/ ground rods that are part of the existing Grounding electrode system located where the new pad will be poured. The plan is to pour the new pad around these existing test wells.

It doesn't appear that connecting the new Switchboard to these existing ground rods is necessary but is there any harm or violation in doing so in order to provide the new Switchboard with additional grounding? Also can the new Ductbanks that enter this new switchboard have the ground wire embedded in the ductbank connected to these ground rods?

Is there a particular method that works best for connecting to existing ground rod (Cadweld vs Ground Rod Clamp?)

 

[kwired]

I was finally able to make it to site and found that there are two existing ground test wells w/ ground rods that are part of the existing Grounding electrode system located where the new pad will be poured. The plan is to pour the new pad around these existing test wells.

It doesn't appear that connecting the new Switchboard to these existing ground rods is necessary but is there any harm or violation in doing so in order to provide the new Switchboard with additional grounding? Also can the new Ductbanks that enter this new switchboard have the ground wire embedded in the ductbank connected to these ground rods?

Is there a particular method that works best for connecting to existing ground rod (Cadweld vs Ground Rod Clamp?)

Are you making a qualifying CEE?

Is there already any CEE('s) connected to your GES?

Yes to both questions - I think whatever you do with it is totally optional.

No to first or both questions - still totally optional.

No to second question yes to first - you may need to connect it to the GES.