ECN Forum Forums General Topics of the Trade General Discussion Area what is ground?

ET popped right into my head on that jem Greg.....


~S~

Seattle uses Article 553 and requires a connection to the EGC at the Service point that ends up being the 'shore power' for their floating houses...if that helps with another answer for the question.

http://www.seattle.gov/dpd/static/2008%20SEC%20replacement%20pages_LatestReleased_DPDP017554.pdf

The open question is still a building built out on the end of a pier. There is nothing I see that prevents you from having the service equipment on the pier but it looks like you still need the ground electrode back on the shore. For that matter even if this is a 250.32 building, fed from a service on the shore, the required ground electrode at the building will be back on shore or a made electrode on the bottom.
"I ain't inspecting that one in the winter"

ok, a made elctrode.... , like what? an anchor? ~S~

An anchor?
Sure, as long as it is buried 30" below the bottom, 2 sq/ft of area, 1/4" or greater thick and connected with a 250.66 conductor

Greg, to answer your question, Fixed buildings on piers fall under article 555. 555 does not address anything specific service grounding. The service is required on shore are identified on floating docks and marinas. The options I can think is either put the service on shore and ground it there, run just the ground back to shore or work with the AHJ and round the ground down the bottom of the water. The latter may require additional approval form jurisdictions. I would imagine typically the jurisdiction stops at the beginning of the pier. It would be a case by case basis with the local AHJ

In general, water is not considered conductive because its not in its purest form. Its the impurities in the water that makes it conductive. I would imagine the chemical composition of the water varies greatly form one moment to the next as the water moves around. Here where I am at, the water can be salty the a few hours later, its fresh water.

In a side note, earlier in this string, I spelled out the difference between the GES and the EGC systems. My intent was only because both systems were talked about in this string. In my personal experience, these two subjects are all too often misunderstood and have confused even good electricians, IMOP, its one of the most important subjects to understand in the trade. Although many of us understand the topic, some don't and with both of them were mentioned, I felt it should be touched on.

Grounding and bonding is just a pet peeve of mine.

I bet most AHJs are going to want to see a service disconnect up on shore with a ground electrode system there for a building on a pier. I am still not sure how the reconcile 250.32(A)
It would be very easy to argue article 555 does not apply if there are no docking facilities on this pier.
I will ask the boys over on Florida IAEI since buildings on piers are pretty common here. I just never had to do one myself.

The more I think about this the more I think I would call the whole pier the "building". The service disconnect would be at the nearest point of entry, the foot of the pier (beach side) and you would connect the ground electrode system there.
Everything else is just a feeder or a branch circuit.

That would be my guess with the AHJ. The dock itself would likely fall under the of the water its built over like the Army Corps of Engineers, the house itself would likely fall under the local applicable building and electrical codes.

I don't think that 250.32(A) would apply here. I would contend that in this scenario, 250.32(D) would apply. If the service at the foot of the dock on the shore and the house were under the single "management", the the GES at the meter would all you need provided an equipment grounding conductor was ran with the feeders out to the house.

well it's the whole theory part of it Sparks, but 250 never really spells it out

as we know, one of the chief GES reasons to exist is supposedly to give lightning a place to go.

so shorter and more direct routes would be appropos

in fact, i've heard it argued that a GEC would be better tied to the noodle at the weatherhead of a service, rather than meter or panel (poco preferenced)

so while i can imagine the AHJ being ok with a shore service GES, and a fat EGC run out to the end of a pier with the feeder & maybe 'bond' the water like pools do now with metal ladders , i can't see the theory end of it being 100% without hiring Lloyd Bridges....

~S~