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I'm adding several new circuits to my main electrical panel as part of a kitchen remodel. The panel with accommodate the new circuit breakers, but it does not appear to have enough neutral and ground terminals.

Once complete, my panel will have 17 circuit breakers, but only has 23 total screw terminals for grounds and neutrals. I believe this is because it is a older panel, from a time when each circuit was not required to be grounded.

Short of replacing the whole panel (which is not within my budget), what are my options for getting all the neutrals and grounds connected properly?

I've read that two or more neutral wires should never share the screw terminal, but grounds can if the panel is designed for it. This isn't really an option for me though, since the 17 neutrals would leave only 6 screw terminals left to connect up all 17 grounds. Even if I used wire nuts to combine multiple grounds together before going to the terminals, this still seems excessive. At the very least it would be pretty messy.

Can I install an additional ground bus bar? I've seen these at Home Depot from the same manufacturer of the breaker box (SquareD). I'm thinking I could drill and tap some new holes in the side of the panel housing and then screw a 20 terminal bus bar on. Then maybe run some 10 gauge wire between it and the main bus bar just for good measure (but it should be grounded fine just from being attached to the panel housing). All the grounds would then go to this new bar, and all the neutrals to the main bar. Electrically this seems like the best option, but would it pass inspection?

A picture of my breaker box is below. Ignore the neutral and ground in the same terminal on the left. I've since fixed that. The empty breakers are where the new kitchen circuits will attach.

Breaker Panel

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Check the door of the panel to see if the neutral/ground bus allows 2 wires. In main panels the neutral and ground buses are normally connected, and you may be able to connect the neutral and ground from each circuit to the same screw. NOTE: this is not true in sub panels, sub panels separate the neutral and ground. –  Tester101 Jan 28 '11 at 13:20
    
The panel door has no info on this unfortunately. Before I started adding circuits there were some ground wires doubled up though, so some electrician thought it ok to do that. Still, I've have to triple up all the grounds to get everything to fit. –  bengineerd Jan 28 '11 at 23:11
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2 Answers

up vote 6 down vote accepted

The panel you have pictured is a grounded panel but originally designed for just 12 branch circuits. There would be no problem if you added an extra ground buss as long as it is screwed securely to the metal box and bonded to earth ground with a piece of 10 or 8 AWG. Knowing you want to add kitchen circuits, looks like you have plenty of capacity. Minimum of two 20 amp convenience receptacle circuits (GFIC), one for the fridge, one for the dishwasher, and one for lighting. Looks good to me. I'd pass it on my inspection.

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Kitchen circuits will be: Fridge, Range, Microwave, Dishwasher, Disposal, Lights, Receptacle 1, Receptacle 2. (There were 2 circuits to the kitchen before, so its a net of 6 circuits added.) –  bengineerd Jan 27 '11 at 21:37
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Gas range, microwave and disposer do not require home runs, but if you have room go for it, but not necessary. Group them if you want. –  shirlock homes Jan 27 '11 at 22:26
    
You seem to be familiar with this panel, does it allow connecting the neutral and ground to the same screw on the bus? I notice it was done on one of the screws in the picture, but I'm not sure this panel is rated for that. –  Tester101 Jan 28 '11 at 13:25
    
Putting two wires in a ground lug is not considered a double tap. It is done all the time. Some electricians like to keep the neutrals and bare grounds on separate lugs however, even though all the lugs are at the same potential. Often see bare grounds twisted and band bonded (2 or 3) and connected to one larger lug. I need to consult the recent NEC changes, got me curious now. –  shirlock homes Jan 28 '11 at 21:08
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You have a huge number of tandem breakers in your panel. That's why you have run out of terminals for neutral/ground. Some panels have a limit on the number of tandem breakers allowed, so look in to that.

It looks like you have 100A * 240V service, and about 160A * 240V of circuits. That doesn't necessarily mean you're overloading anything, since you don't actually run all circuits at full load all the time. Consider calculating your anticipated loads.

I can't tell what gauge wires are supplying your service. If they are only big enough for 100A, and you decide to replace your breaker panel with a 200A panel, you have the additional cost of upgrading those wires.

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You'd have to do demand calculations in order to see if the demand is too great for the 100 A service. Not just add up the breakers. –  Vebjorn Ljosa Jan 27 '11 at 19:13
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Please don't make assumptions, infer code violations and offer (expensive) advise on topics that you have no reference for. The number of branch circuits is not limited by the size of the main breaker. –  shirlock homes Jan 27 '11 at 19:20
    
The one piece of documentation I have for the panel says that the bottom 4 slots on each side will all accept tandem breakers. So its 12 normal slots, expandable to 20 with tandems. 100 Amp service. The NEC has a way to calculate the service level you need based on your appliances and such. It worked out to 125 for me, so I'm a bit short there, but not much. I'm hoping to get by for a bit and upgrade to 200 amps later. At $2,500 its just not something I can afford right now. –  bengineerd Jan 27 '11 at 19:47
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I noticed that you have separate branches for areas that are normally together, like bedroom, crawl, hall etc. Someone got a little carried away. Low use on the separate branches. I only see one 30A DP. Dryer? No ele range, water heater etc. You will be fine. A small sub panel is also an option, but think an extra ground buss will work fine and be safe. And it's LEGAL! –  shirlock homes Jan 27 '11 at 21:13
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OK, edited to apply the wisdom of the comments. –  Jay Bazuzi Jan 28 '11 at 3:52
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