Adding a neutral buss bar

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Old 10-10-20, 06:44 AM
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Adding a neutral buss bar

I am wiring a new home I am building and need to add a second neutral bar to my load centre and need advice.

I have a 400 Amp Service entry from Eaton (CPM442) and it has only one neutral bar on the left side. Eaton sell a kit to add a second bar (CPM400 kit) but so far, technical support can’t tell me if the kit comes with installation instructions. I am balancing the load on the panel, with all my 240 volt circuits at the top ( they are numerous : I heat and cool geothermally, and in addition to oven, stove top, dryer and hot water, run 240 volt machinery in my wood shop).

At issue is that I have 16 plug circuits that are required to be protected with AFCI breakers, and need to put half on each side of the panel. Obviously, the pigtails on the AFCI breakers won’t reach the neutral bar. From what I have read, I could add neutral pigtails to the breaker pigtails connected with a wire nut but that starts looking messy. My preference is to have a second neutral bar on the right side of the panel.

From reading other posts and forums, if I understand correctly, I can mount the second bar to the panel and run an insulated neutral wire to the large terminal on the left side neutral bar. I would the largest gauge wire the terminal will accept, either 4 or 6 copper AWG.

Am I correct in this assumption, and is there anything I need to be aware of?
 

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10-10-20, 08:01 AM
joed
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At issue is that I have 16 plug circuits that are required to be protected with AFCI breakers, and need to put half on each side of the panel.
You can still do that by filling only one side of the panel. The bus bars alternate down each side. It is not split right side leg A and left side leg B.
 
  #2  
Old 10-10-20, 07:45 AM
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Was a plug-on neutral panel not an option? It really cleans up the neutral wiring.
 
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Old 10-10-20, 08:00 AM
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I’ve not heard of a plug-on neutral panel. I will check with the manufacturer when they open as to whether it is. Thanks.
 
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Old 10-10-20, 08:01 AM
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At issue is that I have 16 plug circuits that are required to be protected with AFCI breakers, and need to put half on each side of the panel.
You can still do that by filling only one side of the panel. The bus bars alternate down each side. It is not split right side leg A and left side leg B.
 
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Old 10-10-20, 08:19 AM
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Trying to balance a residential panel is a waste of time. The loads are transient and dependent on time of day. Balancing a panel is for multi-phase panels.

Neutral bars are built into the panel. Ground bars are added.
 
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Old 10-10-20, 08:22 AM
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Yes Joed, I could do that but then most of the 240 volt breakers would be on the right leg and although I am not sure if it is necessary, I was trying to keep the amps balanced on each leg.
 
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Old 10-10-20, 08:28 AM
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Thanks pcboss. Will check with my local inspector next week. That would be the simplest and cheapest solution.
 
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Old 10-10-20, 08:40 AM
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Looking at Eaton's docs the plug on neutral is not available for 400 amp panels.

Get the kit as it is the correct solution. Don't muck up a new panel with a DIY modification.
Neutral kit for 400 A combination loadcentres iCPM400KIT - i Kit includes 2 neutral bars.
 
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Old 10-10-20, 09:52 AM
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Yes Joed, I could do that but then most of the 240 volt breakers would be on the right leg and although I am not sure if it is necessary, I was trying to keep the amps balanced on each leg.
I'm not sure you understood joed 's point.

If you had only 240V circuits, they are automatically balanced because each double pole breaker is in contact with each of the two incoming hot legs.

If we make the totally unrealistic assumption that all your 120v circuits draw the same amperage, and do so at the same time, you could put them all on one side of your panel and be balanced because half of the breakers would be on one hot leg, and the other breakers would be on the other hot leg. The bus connected to each hot leg zig zags as it runs down the panel, so thinking "left side" and "right side" has nothing to do with load balancing.
 
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Old 10-10-20, 10:22 AM
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I am wiring a new home I am building and need to add a second neutral bar to my load centre and need advice.
With your lack of understanding the basics I question whether you should be wiring your own home. I also question whether you really need a 400 amp service. What is your calculated load?
 
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Old 10-10-20, 01:24 PM
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To expand each breaker top to bottom runs ABABAB. The legs are not left and right.
 
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Old 10-10-20, 05:55 PM
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I appreciate everyone’s comments. I am not an electrician, but in Ontario, one is allowed to wire one’s own home and the Electrical Safety Authority inspects to ensure it is done properly. Power in and to the service entry was done by a licensed electrician. I know my limits. But designing circuits such as where plugs and switches and lights go, including 3 and 4 way light switches, wire runs, pulling wires, and connecting circuits to breakers, including 240 volt circuits is within my ken.
I have 400 amps because I am in the country and have 2 sub panels, and use geothermal for heat, and have a large shop. One sub panel is 200 amp is powered by a Cummins 20 KW generator when there is a power failure. On it are a 60 amp geo hot water tank, a 50 amp range, 20 amp well, 20 amp hot water heater, and a 15 amp heat strip for my air handler. Those are all 240v. Then there are 2 kitchen plug circuits, pump manifold circuits for the in floor heat, emergency plugs, garage doors, fridges and freezers on it.
 
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Old 10-10-20, 06:17 PM
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Hit the wrong button and posted too soon. It is likely the 200 amp sub panel is overkill but the cost differential is minimal.
Then there is a shop sub panel of 150 amps to supply my machinery.
Thus on the main service entry, after the two sub panels, I have 2 60 amp breakers for the geothermal pump and the air handler, 50 amp range, 40 amp future steam room, 30 amp dryer, all 240 v. Then there are a number of 20 amp circuits for kitchen plugs, generator, laundry room, and all the AFCI circuits necessary, plus lights circuits. I have used 40 of the 42 slots available and by code must keep two for future use.
I freely admit to not having the knowledge about balance on a panel, and was questioning how to handle. My thought was to have all the 240 volt circuits at the top of both the left and right legs, and then have the remaining circuits equally distributed down each of the legs. And hence the query about a second neutral bar, which Eaton sell so it cannot be an issue that has not previously arisen.
I will call my inspector on Tuesday to see what his preference is.
Again, thank you all.
 
  #14  
Old 10-10-20, 06:56 PM
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My thought was to have all the 240 volt circuits at the top of both the left and right legs, and then have the remaining circuits equally distributed down each of the legs.
We keep telling you you're thinking about this incorrectly, but it doesn't appear to be registering.

Let's try this with a picture.


Can you see that if you install breakers on ONLY the left side, half the breakers will be on line 1 and half the breakers will be on line 2? By the same principle, any 2 pole breaker (your 240V breakers) will be on both line 1 and line 2.

Make sense now?
 
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Old 10-10-20, 07:27 PM
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I understand that completely. I will relook at everything at the site on Monday.
​​​
 
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Old 10-11-20, 05:13 PM
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I went to site today. Couldn’t wait until Monday.

In retrospect, I should have asked the following question :

The first four spaces on each side of my service panel are occupied by a 200 amp breaker connected to an emergency sub panel (generator) and a 150 amp breaker for a shop sub panel. My only neutral bar is on the left side.

I have 1 20 amp and 16 15 amp AFCI circuits. Can I install them all on the left side?
And then install the following circuits on the right side : 2 60 amp, 1 50 amp, 1 40 amp, 1 30 amp 240 volt circuits, and 5 20 amp, and 7 15 amp 120 volt circuits?

I understand that there is no way this load will all be used at the same time. My previous question of “balance” was intended to address the fact that under this scenario the total potential amperage is 240 on the left, and 445 on the right. (Excluding sub panels)

I completely understand that I cannot have a 120 volt circuit, followed by a 240 volt, and another 120 volt occupying for example the first four spaces on one side of a panel, and that it would have to be 120/ 120/240, or reversed.

Again, thanks to all who are helping me.
 
  #17  
Old 10-11-20, 05:37 PM
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I have 1 20 amp and 16 15 amp AFCI circuits. Can I install them all on the left side?
And then install the following circuits on the right side : 2 60 amp, 1 50 amp, 1 40 amp, 1 30 amp 240 volt circuits, and 5 20 amp, and 7 15 amp 120 volt circuits?

I understand that there is no way this load will all be used at the same time. My previous question of “balance” was intended to address the fact that under this scenario the total potential amperage is 240 on the left, and 445 on the right. (Excluding sub panels)
I understand that completely. I will relook at everything at the site on Monday.
Obviously you do not. Please go back to post #14 (the one with pic of a panel), and look and read closely.
 
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Old 10-11-20, 05:48 PM
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Oh crap. I think I understand now. Let me muddle through it a bit more. Thanks Cartman.
 
 

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