Adding a Sub Panel to Breaker Box


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 explain.
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 panels.
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 little difficulty.
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.
David
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I would have gone with copper. But, is it going to be enough smaller to fit into the connectors you mentioned?
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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
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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.
Thanks, David
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.
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.
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...
Right. The new sub panel has a separate neutral and ground connections. It makes no sense to me that they ever did connect the common and ground to the same place. But I am not an electrician.
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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.
Cheers, Wayne
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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.
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. 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 pin!!!! :-)
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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.
David
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Correct. Ground and neutral have to be connected somewhere, but they should only be interconnected in one place, and the main service panel is the designated place.
Cheers, Wayne
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It's always good to learn something before learning it the hard way.
Thanks, David
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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 sub panel....
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Yep. I used an insulated no. 6 copper wire.
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*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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Be certain to isolate the neutrals and grounds in the new sub panel!! removing the bonding screw!
I too would of used copper!
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wrote:

I would use copper, not aluminum.
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