Technically the terminals are probably only approved for one wire each.
Practically speaking jurisdictions in Texas when I was a contractor years
ago, allowed three #12 wires under one screw. A #6 wire which is what a lot
of these are approved for will be several smaller wires twisted together.
Two or three # 12 wires shouldn't be much different but they may not be
As for a ground and a neutral being on the same bar, the ground must be
bonded to the neutral at the first means of disconnect. If your breaker box
contains the first main breaker disconnect for your system, then it is okay
for them to be together. Leave them alone; they are bonding with each other
If you have a main outside and your breaker panel is inside, that might be a
problem. If your panel is a secondary panel or sub-panel, then the grounds
should have a separate bar from the neutral. The bonding between the
neutral and the grounds should only be at one place and that place should be
at the first means of disconnect. If it were otherwise, under a fault
situation, surge current from the fault would divide proportionately to the
resistances of the multiple paths back to ground. That would put fault
currents in your neutrals.
There are other issues such as rf currents, induction, and noise that could
interfere with electronic circuitry through out your working system in case
of a fault.
In reality, it happens all the time, and it usually isn't a big deal. It is
not optimal, and it could be a serious problem in certain circumstances.
Randy R. Cox
In the US the answer is no. YMMV Each current carrying conductor,
including the neutral; must terminate in it's own terminal. Most panels
are listed for multiple, usually two, Equipment Grounding Conductors in
a single terminal.
Well we aren\'t no thin blue heroes and yet we aren\'t no blackguards to.
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