Thread: No visible ground 40 unit bldg

No ground in panel or water service in unit of 40 unit condo bldg. I always thought downstream panels' neutral should not be bonded but there is no ground here unless the panel connection to feed is the ground. Outlets all tested correct and grounded.

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Ross,

No ground wires? Hmm. Could the grounding be provided by metal conduits?

Such a rookie. Thanks.

Originally Posted by Gunnar Alquist

No ground wires? Hmm. Could the grounding be provided by metal conduits?

Ross,

Don't need to let them off that lightly, though.

Yes, likely 'metallic raceway', but ... that bushing and nut in your photo is in concentric knock outs ... and every electrician should know that is *not good*.

Depending on how old the building it, it may have required ground bonding bushings or lock nuts and ground bonding jumpers at the time of installation, or it might just need them to be installed now.

Just because electricians, manufacturers, etc., were not aware of the problem for many years or decades does not mean the problem did not exist then, nor does it mean the problem does not still exist today (it does - electricity does not read the code book to find out whether or not it is allowed to cause a problem and create havoc and cause shock or fires).

The problem with concentric knock outs is (if you've looked at them) that there is only a small area of metal on two sides connecting the small left-in-place-knock-out-ring which is then connected to the next one via only two more small areas of metal, and, to make matters worse, these *are designed and intended* to fatigue and break easily.

Between the fact that there is a high resistance through those small areas of metal, and the fact that many times one or both sides are broken through, there may not be any ground path there any more, or at best a very limited ground path.

Especially on the feeder conduit entry, that needs a ground bonding bushing or locknut with a ground bond to the enclosure.