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#17275 11/23/02 08:23 PM
Joined: Jan 2002
Posts: 1,457
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Helped out a fellow sparky today on a remodel job. Panel was full, added a few mini breakers. The neutral bar was also full so he installed another ground bar. He connected the egc's and neutrals to this bar. This is in a service panel where the main ground bar is bonded to the panel. He insists it's ok but I don't think so. I have never thought about doing this so I haven't given it much thought. Ok guys discuss!

#17276 11/23/02 08:30 PM
Joined: May 2001
Posts: 552
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Hmmmm...
That would make the neutral solely dependant on the mounting screws used.Doesn't sound like a good idea to me.There should(IMO)be a jumper wire installed from the existing bar to the new one.


Donnie
#17277 11/23/02 08:36 PM
Joined: Aug 2001
Posts: 7,520
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You'd have neutral current flowing through part of the panel's outer casing during normal operation.

That doesn't sit well with me.

#17278 11/25/02 08:12 AM
Joined: Oct 2000
Posts: 5,392
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Paul,
remember, our entire system from the MBJ to the x-former is a combo noodle/grounding conductor.
(that evil noodle of ours...the root of many problems here....)

The 02' has dictated that all noodles be under dedicated terminations, so this then creates a space problem for which added G-bars is going to be a common fix.

Now i'm wondering about how to obtain a 'floating' G-bar for similar sub-panel dilema's
[Linked Image]

#17279 11/25/02 10:51 AM
Joined: Apr 2002
Posts: 7,381
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Gentlemen:
If it's the main panel, with the main disco, then that's where the neutral is bonded to the ground conductors, correct?
If you are adding another termination bar (neutral/ground) the bar you are adding should (IMHO) have a jumper connected to the "factory" bar. The "jumper" should be sized according to the incoming neutral that is connected to the "factory" bar.

If it's a sub-panel, then there has to be a "ground" bar, and an "isolated" neutral bar, with a "ground" and "neutral" conductor for each.

If the "added" bar in your scenario is "mounted" to the panel enclosure, then you are using the panel enclosure for a "neutral & ground connection back to the "factory" bar & bond. The current passing through other "grounds" depending on the resistances. Not Good.

Hopefully my explanation above is clear enough to understand.
John


John
#17280 11/25/02 01:00 PM
Joined: Mar 2001
Posts: 2,056
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It would have been better to relocate the grounds from the original neutral bar to the new ground bus to free up the spaces for the new neutrals.

#17281 11/25/02 01:04 PM
Joined: Nov 2000
Posts: 2,236
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And still have a #4 bonding jumper between the bars...


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI
#17282 11/25/02 02:06 PM
Joined: Oct 2001
Posts: 597
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E Scott,

Interesting twist!

The problem is that the branch circuit neutral current is forced to return to the bond point through the enclosure of the service, even though we're only talking about half a foot or so. This applies to each neutral that is connected to the added ground bar.

That "half foot or so" of sheet metal can't be a neutral, even though its the service disco.


Al Hildenbrand
#17283 11/25/02 04:38 PM
Joined: Jul 2002
Posts: 103
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My Square D info says that the add-on bar is for equipment grounding ONLY. The factory installed neutral bar(s) are required to have a minimum number of terminals for landing neutrals based on the number of circuits the panel is arranged to supply. Where there are a large number of equipment ground conductors they MAY be landed more than one to a terminal IF the panel is so listed (and marked) OR an additional bar kit must be installed. Terminals used for equipment grounding are treated differently than those for neutrals because the connection does not undergo the cyclic loading and expansion/contraction of the current carrying neutral.

#17284 11/25/02 05:10 PM
Joined: Oct 2000
Posts: 5,392
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Quote
That "half foot or so" of sheet metal can't be a neutral, even though its the service disco.

then what do we can an all mettalic service ?

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