Robert Green wrote:
"The Freon Cowboy" wrote in message
m...
yes, its permissible, and done everywhere .

FWIW, it looks like the reason it's done everywhere is that the "by the
book" solution is pretty drastic. As far as I can tell from what Square D
said, to gain more neutral holes, I'll have to change out the whole box.
That's a little too drastic a solution and I have a few options. One is to
disconnect the central A/C since we never use it. That would free some
openings. Another is to mount the supplemental Cutler Hammer ground bus bar
in the case, feed it with a large diameter wire from the existing neutral
bus bar and move the three or four ground wires now connected to the bus
(old house, very few grounded outlets) to the supplemental ground bus bar.
The third seems to be what most people do. Put two wires under a setscrew
and print up a big label for the box "Disconnect Main Breaker Before Neutral
Rewiring!"

--
Bobby G.

Bobby
That last idea is a problem right from the start. The reason that the
electric code specifically forbids connecting two neutral conductors
under one terminal is that the two circuits will be loaded and unloaded
in a random way during normal use. Each of the conductors will then
expand and contract at different times causing the connection to the
more lightly loaded of the two wires to be looser than the connector is
designed to be and inducing heating in that connection beyond it's
design limits. That leads to connection creep which gradually makes the
connection less and less firm. Eventually arcing occurs and the neutral
goes open leaving a circuit that appears to be dead energized from the
breaker all the way back to the open neutral connection inside the
panel. As one example of the danger to persons the screw shell of
Edison based screw in light bulbs would be energized at 120 volts to
ground. Someone thinks the bulb is burned out and tries to change it.
If their finger comes in contact with the screw shell while they are
unscrewing the bulb they get a shock. Even if there is no path to
ground through their body their startle reaction alone could throw them
off of a ladder or cause them to fall. If they are also in contact with
some grounded conductive surface such as the metal surface of an
installed lighting fixture they could receive a fatal shock. SquareD
makes an isolated ground buss bar that is designed to be added to a
panel were isolated grounds need to pass through a panel without being
connected to other Equipment Grounding Conductors (EGC) in that panel.
Installing one of those buss bars is a perfectly safe way to add
additional neutral terminations to any panel No matter what the panel is
being used for. It would be a technical violation of the panels listing
and the listing of the isolated grounding buss bar but it would not in
fact be unsafe as long as there is plenty of room in the existing
cabinet to install the buss bar and the room to bend the additional
conductors to each terminal. The additional buss bar would be connected
to the the original buss bar by a copper conductor at least as large as
the main bonding jumper called for in 250.28 Main Bonding Jumper. (D) Size.

250.28 Main Bonding Jumper.
For a grounded system, an unspliced main bonding jumper shall be used to
connect the equipment grounding conductor(s) and the service-disconnect
enclosure to the grounded conductor of the system within the enclosure
for each service disconnect.
(D) Size. The main bonding jumper shall not be smaller than the sizes
shown in Table 250.66 for grounding electrode conductors.

If your panel is two hundred amps or smaller then that wire need be no
larger than number four copper. IF AND ONLY IF YOUR PANEL IS ALSO THE
SERVICE DISCONNECTING MEANS FOR YOUR HOME you could just install a
supplemental Grounding buss as others have already suggested. Since the
Equipment Grounding Conductors and the Grounded Current Carrying
Conductors; by which read neutrals; are bonded to each other and to the
cabinet you can use the supplemental EGC buss bar in the same way you
use the neutral buss bar. In order to avoid having neutral current
traveling on the bonding connections through the steel of the panel's
cabinet you just add a main bonding jumper between the two buss bars so
that current from any neutrals you terminate on the extra buss bar will
have a low impedance pathway back to the utility neutral and thence back
to it's source in the utilities transformer secondary winding.
--
Tom Horne