[OP]
Member
My shop has grown to the point that I need addition circuits, and am in the process of adding a new 100 amp box. Two questions, one the new panel has only one ground connection, do I put both the neutral and ground wires into that one connection? Second, do I need to connect a second ground rod to the sub panel. Also, any other special things to watch for? This may be simple, but I would like more educated opinions. I will be moving the existing circuits for the shop to the new box.
Ken
Member
You should not tie the ground and neutral wires together at the sub panel. Furthermore, you should remove any physical connection that may already be there. There must be only one physical location where this is done anywhere within your wiring. You can run a ground from your main panel or you can establish one for the sub panel according to the local code requirements. Where I live, the preferred method is to ground the sub panel exactly like you would the main panel.
Member
Your new panel should have a neutral bar and a ground bar. They should NOT be bonded in a subpanel. Run four conductor wire from existing panel to new panel. Groud bar to ground bar, neutral bar to neutral bar, main panel cb two hots to subpanel two hots. Only bond at the main panel.
Glad its my shop I am responsible for - I only have to make me happy.
Member
Which panel are you adding? Perhaps someone here will know how to unbond the neutral and ground in that panel.
Member
Not all new panels come with a ground and a neutral bar, that you can disconnect. I bought one recently (to use as a subpanel) and then realized after getting home that I had to buy a separate ground bar. Neutral and ground do not connect until the main panel.
Profanity is the futile effort of a feeble mind, to exert itself forcefully.
[OP]
Member
My main panel in the house has the ground and the neutral connected to the same bar. The new panel being installed in the shop has only one lug on the ground strip, so although I plan to run a four conductor wire I only have a single lug in the sub panel.
Ken
Contributor
You will have to buy a kit or get another Block, the neutral will have to be on an isolated block. It cannot connect to the ground in anyway except at the main panel. The idea is to have only one path to ground. If you connect the two to the same spot you can cause a short with a failure. Think of the Subpanel as an outlet. The neutral is the return. The ground is the other path. If you have ever been shocked by one of the old 3 prong dryer systems you would know what this means. It is the reason that they have 4 wires now. Dan
[OP]
Member
Okay, it seems I need an additional bar to install in my new panel, I can handle that. I have done a lot of wiring in my younger life with my Dad. Nothing much in recent years, just to be sure I understand would you guys clarify for me the terms neutral and ground. That has always been a little confusing for me. I am going today to purchase the new bar for the sub panel, the four conductor wire, and the new breakers. But other than running the wiring, I won't connect until I am sure I understand the information I am getting from you guys. You all are being a tremendous amount of help and many thanks for you time and expertise.
Ken
Member
Hire a licensed electrician. No more worries
Contributor
Main panels and subpanels have different requirements for bonding Ground and Neutral. Carry that box back or just get another bar to add to it.Originally Posted by Ken Parris
Do a Google search for "what is the difference between ground and neutral", and you will find what you need to understand it, including even a youtube video. I just did that search, but didn't bother to read any to find which would be the best explanation.
Also, be aware that some of those panels don't have bars that go down far enough to cover all the available spaces for breakers. It's only a few bucks more to get one that allows you to use the maximum number of spaces available.
Last edited by Tom M King; 09-27-2015 at 9:17 AM.
Member
Your sub panel ground wire should run to the ground bus in your main panel. When you install the ground bus in your sub panel, scratch away some of the paint in the panel tub where the bus will be mounted. This helps bond the tub of the panel to the ground bus.
This is what you need to add:
This is what your panel should look like when terminated:
Notice the ground bus on the left of the breakers. (look for the green and bare wires) The ground bus is mounted directly to the tub of the panel and does not tie in to the neutral bus. There is a separate ground conductor that ties it into the system.
“Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain
Member
Here's a better wiring diagram
“Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain
Contributor
Maybe I missed it, but I don't think Ken's second question has been answered: Whether he needs a second ground rod for the subpanel, in addition to the question about bonding ground to neutral at the subpanel. Art, Julie and the other bona fide sparkys/EEs can answer this better than I, but it's my understanding that this depends on whether his shop is in the same building as the main, or in a separate structure. Here locally, a subpanel in a separate building requires it's own ground rod, while it does not if in the same building.
[OP]
Member
Julie, your "better wiring diagram" answered all my questions. I feel comfortable following it and getting the job done. And to all the others that have contributed, thanks so very much. It is really something having all this expertise to draw information. I have my own areas, I have done a lot of work in this area, but not for a long while. Anybody need any information about asphalt plants, I can help you. Again many thanks.
Ken
[OP]
Member
By the way, my shop and garage are part of the main house, all one structure. And by Julie's good diagram and David's comments it looks like I do not need a second ground rod on the sub panel.
Ken
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