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At a condominium sub panel, which fed by 3 wires from a main disconnect only, where there is NO main panel dedicated to subject sub panel, is it still allowed to bond ground/neutral bar to the sub panel' s chassis?

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    Is the neutral bonded to ground at the disconnect? If not, then your subpanel is really a main panel, and N and G should be bonded. Or if this is existing wiring and they're currently bonded, that's grandfathered and still okay. – Nate S. May 13 '19 at 21:06
  • Thnx!, I am not sure if the N & G are bonded at the disconnect. This is an older 1985 multi-family building with many condos units, so each unit has it's own disconnect at the main and it's own panel at the unit' s interior . However, even if it gets a grandfathered pass, will adding an isolated neutral bar to the panel while converting the existing bonded bar to be a ground bar only is advised to make the panel safer! – H1991 May 13 '19 at 21:16
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    If it's a grandfathered installation, you need to keep them bonded unless/until you run a new ground wire back to the disconnect (assuming it's bonded there). Removing the bond without adding the ground wire will make it much less safe, not more. – Nate S. May 13 '19 at 21:19
  • What wiring method was used for the feeder to the unit's panel from the meter/disconnect? – ThreePhaseEel May 13 '19 at 23:21
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You have a 4-wire feed

You actually do have a separate ground wire, even though you can't see it. It's the metal pipe the wires run in.

Commercial scale buildings like that usually use conduit for feeder. And 1985 is before PVC came into vogue. So almost certainly, this conduit is metal and non-flexible, and is the valid and proper grounding path. I have four large buildings with not one green or bare wire anywhere in the complex.

Still unclear on if this is a main or sub panel

You need to check with the condo association about where exactly your neutral-ground bond occurs. If there is a main breaker down in a utility room somewhere, it is assuredly there. But you have to ask.

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  • Thank you for great answers ! – H1991 May 14 '19 at 16:48

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