I have followed some advice that a couple of folks here gave me on
another thread and decided to add a sub panel to the breaker box.
So I stopped at Home Despot today and got another panel that has the
capability of adding 12 more circuit breakers. I got one of the
employees there to help me pick out what I need and I think he did a
pretty good job except for one item I am not sure about. I will
I got the new panel set up pretty easy but when I tried to connect the
new panel to the existing one, I ran into a problem. The salesman
recommended I use aluminum 6 - 3 with ground wire to connect the two
The new panel has separate connector bars to hook up the white and
ground wires. I was able to get the wires into the new box with only a
In the existing panel, the white wires and ground wires all connect to
one bar. It is full and I can't see a way of adding more space and the
connectors are not big enough to take the large wires.
First, I am wondering if it was a mistake to follow the salesman's
advice and go with aluminum and if I went with copper could I have
used a smaller diameter wire with the same capabilities.
If I stay with the aluminum wire I am going to need some sort of
adapter/connector for the larger wire.
copper would have been smaller, but all you need is a small ground bar,
which the same store should sell. Bolt it down in the old panel and link it
to the existing bar with number 6 copper. You'll need to move a few small
ground wires from the existing bar to the new one, to make room
I did the additional ground bar today and jumpered it with a number 5
copper wire as you said. I gof the old panel back together and the
new panel is now ready to get some circuits wired into it.
To repeat ............................ the ground and neutral should
ONLY be common in the original or main panel.
In all other (sub) panels the neutral and ground should be
separate.Remove the (maybe at first) not obviuos screws that connect
the neutral bar to the ground/fram of the new box. A secondary panel
such as this is sometimes called a 'Pony panel'.
In this jurisdiction each Pony should be connected to a suitably sized
circuit breaker in the main panel. For example in this house, from the
200 amp main panel, a 100 amp CB connects the first sub panel near the
kitchen some 30 feet away. Another 50 amp connects second sub panel in
the garage/storeroom. A 30 amp feeds a small panel in the workshop.
Just FYI, the ground to neutral connection at the service is a
critical safety measure. The point of the equipment grounding
conductor is to cause the circuit breaker to trip if a hot conductor
should accidentally contact the grounding conductor or anything bonded
to it. To do that, you need to complete a circuit, and the neutral to
ground connection at the service is part of that circuit. The reason
that neutral and ground are separated downstream from the service is
that under normal working conditions, you want all the return current
flowing on the neutral and none of it on the ground.
I agree; it make a lot of sense to me that the neutral is connected to
ground, once, at the entrance or main panel point; creating a sort of
zero voltage point. Each house having a ground rod.
Then if a fault occurs in one of my appliances and say something
inside one of them breaks down (a motor winding, door switch, stove
element, or whatever) and contacts the metal frame of the appliance, a
fault current flows directly back to that ground point making the
appliance safer to touch. Also any slight voltage drop along the
length of the neutral wire, under normal conditions or in the case of
a broken off neutral cannot electrocute somebody.
Also having worked on outside telephone lines it was somewhat
comforting that everything outside was Multi Grounded Neutral (MGN).
In other words most guy wires, cable supporting strands, transformer
casing and every single domestic service are grounded.
In our house, which has copper hot and cold water plumbing we have
taken care to 'bond' those to the electrical ground. This is not
'using' the water pipes as the ground but would help to avoid any
dangerous voltage potentials.
BTW the assumption, by some, that a ground is 'just the same thing as
the neutral' is not common.
But can denote a somewhat careless and/or not knowledgeable attitude
towards electrical safety.
The sort of attitude that thinks it's OK to cut off the ground
So it seems like you are saying that even tho the ground and neutral
have separate connections on the sub panel it is not just ok but a
good thing that the ground and neutral are connected together in the
main panel. Am I reading that right?
I knew that having circuits properly grounded was a safety issue but I
never exactly knew why.
Was the wire used between main and sub panel fully insulated? If it
had a bare neutral or bare ground that may be a issue since the bare
wire could contact the sub panel insides or where the wire enters the
*I usually go with copper and I would have made the subpanel bigger. If it
hasn't been done already the ground wires in the main panel usually can be
doubled up. The white neutral wires cannot be doubled up. By doing this you
may be able to free up a screw or two. Read the label on the panel to see
if it is approved for this. Other wise you can do what RBM said and add
another ground bar. I have also seen adaptors that go into two screw
terminals to accept one big wire. You would most likely have to go to an
electrical supply for this.
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