I have underground service conductors hitting a meter on the outside of a saw mill then next to the meter is a wireway. From there I have a 400A panel and then a 100A inside that building for the mill. Then from the wireway I am tapping and bringing conductors to two other panels about thirty feet away for some sheds. Now I am going to ground my service in the wireway in accordance with 250.64D3. My question is if I have to have electrodes for the sheds? I know for feeders and branch circuits I have to follow 250.32B, but the sheds wouldn't be feeder conductors.
Grounding electrodes for Services
- Thread starter stephena
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I wanted to answer "sure", but I've yet to prove it by Code. Best I can do so far is 250.50 that mentions "at each building or structure served".
The requirement has to be there somewhere
jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
Those panels at the sheds gotta be mounted on some type of "structure" so a GES is gonna be needed.
starbolin
Senior Member
- Location
- Rancho Buenaventura, California
Where are the two auxiliary panels mounted? They may be considered structures. If the sheds are fed by more than one branch circuit then the need a grounding electrode per 250.32(A). The electrodes are only connected to the EGCs and not the neutral. 250.32(B)
I don't understand your comment about the sheds not being feeder conductors.
I have no doubt in the requirement... what is my Code reference.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The OP describes the shed wires as being connected in the wireway next to the meter, and presumably upstream of the existing disconnects.
That would make the shed wiring service conductors, which would be run as three wire, w/o EGC, and they would therefore require their own GES and ground/neutral bond in some sort of panel at each shed.
There may be an issue with grouping of service disconnects, and the shed panels certainly need to be service rated.
The conductor size to the sheds could be less than the ampacity corresponding to the POCO service amperage as long as the unprotected conductors are not run inside the building(s) and the shed main breakers protects them and they can carry the calculated shed loads.
Since the conductors are unprotected service wires, the grounding at the meter next to the wireway does not do any good for them.
I suppose that if the OP runs a GEC (not an EGC?) along with the circuit wires he could then bond that to the main building GES, but there would still, IMHO, need to be a local GES at each structure, especially since this is a service.
If the OP puts the OCPD at the wireway end, then they become feeders and everything changes. But still requires a ground at each structure (depending on code cycle.)
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jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
How about 250.24(A)?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
In particular, (1) requires a GEC connection next to the service disconnect, and if my interpretation is correct each shed has its own service disconnect.
PS: But, looking more closely at the exact wording, it appears that perhaps the ground at the end of the single POCO service lateral or service drop is good enough for all of the other service wires going on from there. In which case maybe there is no requirement for an electrode or a GEC arriving at the sheds.
PPS: What Augie said....
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I think that will do it. Thanks.
I saw that and first thought "well, it has a electrode at the service" ..
I would prefer the word "structure" be included as he dictionary states"premises":
2. premises.
- a tract of land including its buildings
so one could argue that the groundning electrode at the meter serves as the "premises" ground.
Since a feeder to a separate building requires a GES it only makes sense that a service would but proving that was difficult to me.
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devil's advocate here..
does it ? What if the GEC is connected ahead of the service disconnect, for arguments sake let's say at the weatherhead and the service conductors run outside 100 ft to the disconnect ?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
See PS and PPS in my post. We crossed in the night.
again..being devils advocate....
definition of a premises includes "buildings"
The service has a GEC connected at the wireway...
That connection serves as the GES for the premises.....
250.24(A) says we will have a a GEC connected to the grounded serviced conductor at each service. The OP has that at his wireway. His runs to his buildings are part of the premises wiring.
Don't get me wrong. I would expect to see a GEC at each building but if he asked me to show him a Code reference I'd be head scratching and in hopes he did not know the webster definition of a premises
,,my head hurts..I'm taking break
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Thanks, my head hurts now also.:rant:................
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The thing that hurts my head the most is the realization that even with all I have learned, here and elsewhere, I still, deep in my gut, feel that a ground electrode and GEC right at the shed is doing some positive good in this situation.Thanks, my head hurts now also.:rant:................
Quick comment, just for completeness, even though no local ground electrode seems to be required, it is imperative to use a service rated panel and to bond the incoming grounded connector to both neutral and EGC on the building side.
That is exactly how it's set up. My meter base is outside on the wall of the saw mill then adjacent to that is the wireway and from that point is where I attach to my GES. From there I go into the mill to feed a 400A and 100A panel and also take two sets of conductors 30ft away to feed 2 200A panels going to some sheds.
Keep in mind, I'm just having a problem with semantics... I fully support the installation of grounding electrodes at the detached buildings. I just have a bit of a hang-up about being able to show you my inspection calls in the book.
The AHJ has the final call and I would fully expect him to required grounding.
The AHJ has the final call and I would fully expect him to required grounding.
I would expect grounding electrodes as well, but the more I read it and couldn't find a specific code reference I thought it would be legal. If I connected to the GES at each disconnect then it is obvious. If it was only one panel, lets say, and my meter base was on a pole 30ft away outside then I wouldn't have to reattach to the GES so why would I in this case? For feeders and branch circuits it's clear but these are as you know service conductors. Guess I can always wait for the inspection then see if he fails it and then what he sights. 250.58 kind of supports this installation as well.
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