Need help with an explanation

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DaveSchlarb

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Colorado Springs
I'm circling back to some issues that my electrician diagnosed in the office building that I manage. One of our panels (120/208) is fed only with phase B, and jumped to the second bus bar in the panel, it's also ungrounded but that's another story all together. I'm having a really tough time explaining to management why this is bad because, like my electrician, I can understand the technical side of things, but I'm terrible relating it to that someone that doesn't.

Thanks Everyone!
 
Is the panel in question fed by a UPS ??
It is not terribly uncommon to find that situation where panels are fed by UPS or some supply that only has a 120v output.
It allows you to use each space in the panel.
 
augie47 said:
Is the panel in question fed by a UPS ??
It is not terribly uncommon to find that situation where panels are fed by UPS or some supply that only has a 120v output.
It allows you to use each space in the panel.
Click to expand...
When the building was built the panel did have 2 phases feeding it through a power conditioner, since then the power conditioner was removed because, "it was having issues". When that was done someone pulled 1 phase back to add another panel in the area. They replaced the power conditioner with a piece of PVC between the end of the rigid pipe and the top of the distribution switchgear.
 
I am having difficulty understanding your description.

  • For starters, when I see “120/208,” I expect to see three bus bars (for Phases A, B, and C), in addition to places for landing neutral wires and ground wires. You mention only “the second bus bar.” Are there only two (i.e., is this a “single phase” panel)?
  • Also, what do you mean by saying the panel is “ungrounded”? Are you looking for a connection to planet Earth by way of a ground rod, connection to a water pipe, or some other electrode? If so, then it is most likely that such a thing is not needed. But if instead you mean that there is no “equipment grounding conductor” – the green or bare copper wire – running to this panel from the source panel upstream, then you have a safety issue on your hands.

Here is my guess as to what you are describing:

  • This is a single phase panel, and only has two bus bars.
  • It is fed with one ungrounded conductor (most likely with black insulation) and one neutral conductor (white insulation).
  • For now, we will leave out the discussion of the presence or absence of a green wire.
  • The incoming black wire lands on one bus bar, and there is a jumper from that bus bar to the other one.

If that is right, this is neither a code violation nor a safety issue. But that statement is predicated on two things that must be true, for otherwise you have both a code violation and a safety issue.

  • The jumper between the bus bars needs to be large enough to carry the full rated current of the panel.
  • There can only be circuits fed from a single breaker, and each circuit must have a separate neutral wire.
 
charlie b said:
I am having difficulty understanding your description.

  • For starters, when I see “120/208,” I expect to see three bus bars (for Phases A, B, and C), in addition to places for landing neutral wires and ground wires. You mention only “the second bus bar.” Are there only two (i.e., is this a “single phase” panel)?
  • Also, what do you mean by saying the panel is “ungrounded”? Are you looking for a connection to planet Earth by way of a ground rod, connection to a water pipe, or some other electrode? If so, then it is most likely that such a thing is not needed. But if instead you mean that there is no “equipment grounding conductor” – the green or bare copper wire – running to this panel from the source panel upstream, then you have a safety issue on your hands.

Here is my guess as to what you are describing:

  • This is a single phase panel, and only has two bus bars.
  • It is fed with one ungrounded conductor (most likely with black insulation) and one neutral conductor (white insulation).
  • For now, we will leave out the discussion of the presence or absence of a green wire.
  • The incoming black wire lands on one bus bar, and there is a jumper from that bus bar to the other one.

If that is right, this is neither a code violation nor a safety issue. But that statement is predicated on two things that must be true, for otherwise you have both a code violation and a safety issue.

  • The jumper between the bus bars needs to be large enough to carry the full rated current of the panel.
  • There can only be circuits fed from a single breaker, and each circuit must have a separate neutral wire.
Click to expand...

Ok, I just looked closer at the panel... I think that we had a brain fart and assumed that this panel was supposed to be 3 phase... I just went and looked at it and you are correct there are only 2 bus bars. That makes my life easier... but now I wonder if the hot and the jumper are sized right. There was another panel added in this area, and I assume that they pulled a leg back from the original panel (which did have a couple of 2 pole circuits) to feed the added panel.

Now as far as the grounding goes... I think that I do mean [FONT=&quot]“equipment grounding conductor”[/FONT] It's my understanding that the panel was at one time fed by a power conditioner that was taken out some years ago, and replaced with a piece of PVC between the top of distribution switchgear and the rigid conduit leading to the panel causing it not to be connected to the building's grounding system. Would that be accurate?
 
Rigid conduit is an acceptable equipment grounding conductor. You are correct if PVC is placed in the path, the equipment ground would be lost.
 
DaveSchlarb said:
... I'm having a really tough time explaining to management why this is bad ...
Click to expand...
I'm not sure why that's a problem, but a few suggestions, depending on how open-minded or pig-headed the person might be:

The building needs electrical repair. Cough up some bucks.

The building needs electrical repair to be safe.

Some ill-advised changes in the past left an unsafe condition behind that now needs repair.

When the [powerline conditioner?] was removed, they didn't complete the job.

Some equipment grounding conductors were removed and need to be replaced.

When the equipment grounding conductors are present and in good condition, an electrical fault causes a breaker to open.
When they're not, an electrical fault can cause a death.
why-ground.jpg

(the illustration is from the book Wiring Simplified)
 
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