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!

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.

You'd have neutral current flowing through part of the panel's outer casing during normal operation.

That doesn't sit well with me.

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

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

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.

And still have a #4 bonding jumper between the bars...

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.

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.

then what do we can an all mettalic service ?

ps~ on a steel structure.......

Escott,

I would have to say the key issue expressed by everyone [and what I would like to know also] is if there is a Jumper between the existing bus and the new bus.

That would make the Unbalanced Current flow within the Grounded Conductor[s] only - instead of getting to the Grounded Conductor through the Metallic Enclosure.
I know you know this [Ralph Crandom again ...], just added that info to help readers whom may not.

Someone mentioned placing the EGCs on the new bus - which sounds like a good idea too. A Bonding Jumper may still be needed - sized accordingly per highest OCPD of circuits used per the EGCs on that bus.

That's wierd the Factory Supplied Grounded / Grounding Conductors' bus is so limited to available space!
Then again, the amount of Residential work I do is so little, have hardly no clue to what's going on anyway!


Did a Custom House design and install in early 2000, did a Spa last July, and just got a Residential Service relocation / upgrade job last week.
Three Residential jobs in two years [almost three!!!], with maybe 5 between 1995 and 2000 gives me a close to 1 per year rate!

Scott s.e.t.

I'm with Hotline on this part
and this part


but I'm not so sure about this part



NEC proposal for the number of spaces on a noodle bar?

<Scratching my noodle>,
Doc



[This message has been edited by The Watt Doctor (edited 11-25-2002).]