Feeder feeding another bldg which feeds another bldg

[hhsting]

I am not sure if you can do the following or not. Attached sketch shows Swbd in Bldg B which has fdr bkr feeding Bldg C. Bldg C has panelboard C1 which has feeder breaker feeding Bldg D. Bldg D is a small storage about 2500 square feet and is 25 feet from Bldg C. Bldgs B, C, D are on campus same owner. I understand code does not allow multiple feeders feeding bldg such as shown Bldg C fed from Bldg B and again has feeder from Bldg D.

However my question is does code allow situation in attached sketch feeder feeding Bldg C which again has feeder that feeds Bldg D i.e feeder from swbd to trough bldg C and from Bldg C Panel C1 feeder to Bldg D?

 

[petersonra]

Code only allows a single feeder to serve a structure. But I dont recall there is a limit on feeders just passing through.

 

[hhsting]

I guess the question I am asking may not be clear. I have edited post #1 sketch to show parts relevant to the question. Please see attached sketch. My question is does code allow Panel C1 feeder to feed Bldg D panels D1 and Pnl D2 light and power since Bldg C light and power is also feed by feeder from SWBD Bldg B? Does code allow cascading feeder to keep in feeding building.

 

[charlie b]

I believe that the installation shown in your first sketch is completely code-compliant. That includes the feeder from Bldg D that powers a panel in Bldg C. See 225.30(D). The feeder from B to C is 480V, and the feeder from D to C is 120/208V. That counts as "different characteristics."

 

[charlie b]

If your basic question is whether you can go from building to building to building to building to . . . yet another building, the answer is yes. There are requirements unrelated to your question, however. For example, each subsequent building will need its own disconnecting means, and the breaker in the upstream building may or may not count. Also, each building will need its own grounding electrode system.

 

[tom baker]

I agree and see also 225.34. I would respectfully suggest your sketches could be better, perhaps use black ink/pencil on a graph paper. Back in the day I used engineering twin grid, the printed lines were lite blue and didn't reproduce

 

[hhsting]

Bldg C has transformers inside which go from 480V to 120/208V.

 

[charlie b]

I agree and see also 225.34.

Let me offer an interpretation of that rule, as it might apply to this thread. I can have six disconnects that would turn off all power coming from a 480/277V feeder to a building, and all six of those disconnects need to be "grouped." I can also have six disconnects that would turn off all power coming from a 120/208V feeder to a building, and all six of those disconnects need to be "grouped." However, the 480V disconnects do not have to be grouped with the 208V disconnects. Do I have that right?

 

[charlie b]

Bldg C has transformers inside which go from 480V to 120/208V.

And that is why it is OK to have a feeder from D back to C.

 

[tom baker]

And all the disconnects need a label that identifies the source and others, something like FEEDER DISCONNECT 1 OF 2. FED FROM THE BIG RED BUILDING PANEL 6 NW CORNER

 

[PaulMmn]

I agree and see also 225.34. I would respectfully suggest your sketches could be better, perhaps use black ink/pencil on a graph paper. Back in the day I used engineering twin grid, the printed lines were lite blue and didn't reproduce

While I certainly see the advantage of black on white (with bold lines) to take a picture of for uploading here, for many things I'll draw in red, with a blue or black in reserve for corrections! Two versions on 1 piece of paper; saves time re-drawing!