The NEC requires the neutral be bonded to "ground" (the enclosure) at
the service (and earthing electrode(s) be connected to the N-G).
(This is a critical connection that insures there is a high fault
current for a H-G fault, with the fault current returning to the
transformer on the service neutral. The high current trips the breaker.)
As I noted, virtually all services come with a neutral.
All the SquareD panels I have seen come with a neutral bar. A neutral
bar is isolated from the enclosure and has a lug to connect to the
Because almost all service panels have the service neutral bar bonded to
"ground" (the enclosure) there is a means (a "main bonding jumper")
supplied that can be installed to make that connection. Sometimes it is
a strap that is screwed to the enclosure that connects to the neutral
bar. Often it is a screw that goes through a hole in the neutral bar to
the enclosure (it can look a lot like a mounting screw - probably the
green screws for the "solid neutral assembly" in Michael's post).
Ground bars (as in Michael's post) are normally screwed directly to the
enclosure - "ground".
(Occasionally an "isolated ground" is used and the ground bar is
isolated and fed by a ground wire from the source. This could connect to
"isolated ground" receptacles.)
(And it is possible that the N-G bond is not located in the service
circuit breaker panel (it is elsewhere), so the neutral bar is not
bonded to the enclosure.)
The only configuration I have seen is where a neutral bar is supplied
and the source neutral, which is included in almost all panels, is
connected to the bar. A panel could also be supplied with an installed
ground bar, but it often isn't and it is added as a "kit" as in
If used as a service panel, a bond is added from the neutral to the
enclosure ("ground"). The neutral bar can then also be used as a ground
bar. Since that often happens I assume most panels do not come with a
If a subpanel has ground wires it needs a ground bar.
Regarding the 2008NEC, you can't connect a neutral wire to a separate
ground bar. The neutral current path would be through the enclosure and
"main bonding jumper" to the neutral bar. The path using the enclosure
is now explicitly prohibited.
=============I am astounded to read you are another sock-puppet for dimbulb.
Hell, I *named* DimBulb, "DimBulb", after his insane insistence (for
weeks) that a 100W light bulb didn't put out as much heat as a 100W
heating element. John Larkin gave the ditz the "AlwaysWrong" moniker,
and I don't remember who named him "Nymbecile". All fit perfectly.
Sure, I got all that. I just misremembered incorrectly what I put in
the panels. Every box needs a ground, not all need a separate neutral
so I was misremembering that I added the neutral bar, when I did
indeed add a ground bar (just looked) and removed the screws from the
neutral bar*S* (one on each side). I'd remembered adding the two bars
down the side of the bus, but they were indeed ground bars. In
another box I fixed (my MIL's house failed inspection when we sold it)
the ground bar was along the bottom.
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