3 story common grounding conductor

[dm9289]

This problem is in a 60 unit building for older folks on fixed income in an HOA.

Lets break it into 3 unit intervals units are essentially stacked.
Building has several 400amps services with main disconnects having a neutral and ground connected together in disconnect.
Each disconnect feeds about 15 units the wires are tapped in a wireway then they feed individual utility meters then a 70amp fused disconnect.
From the fused disconnect is where the problem begins. From the fused disconnect 3 wires no ground feed each units 70 amp federal panel.
Being as the units are stacked in order to save building damage when replacing panels from federal pacific can I run 1 larger conductor up 3 floors then tap it like the picture shown but of course minus the transformers.

 

[augie47]

What wiring method is employed betwwen your 70 amp disconnect and panel ? ie: EMT, AC, MC ???

 

[dm9289]

Older fabric SE cable

 

[augie47]

Are the 400 amp risers in metal conduit ??

 

[dm9289]

Are the 400 amp risers in metal conduit ??

Yes. Building Main disconnect, meter cans, wire way, and fused unit disconnects all connected with rigid. Then the wire exiting fused unit disconnect is older 3 wire SE

 

[augie47]

The metal conduit can serve as your EGC so you only need to worry from that point to your panels.

 

[dm9289]

From the panels to the units would require a lot of damage