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Old 02-22-2008, 01:11 PM   #1
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Two neutral bars


I did a little search and noticed quite a few questions about multiple neutral bars in a panelboard by the users of this forum so am posting a diagram that I modified from a manufacturers site. Maybe those searching will find this and be able to get some of their answers.

Note: This is a diagram of a panelboard installed as service equipment with a 3 wire 120/240 volt single phase system. Panels installed and being fed from main disconnects that are remote from the panel or if the panel is in/on a detached structure fed with a feeder from the service equipment would not be relevant to this diagram as far as the installation of the bonding means to the metal case of the panelboard. Detached structure panels would also require 4 wire feeders as of 2008.
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Two neutral bars-split-neutral-2.jpg  


Last edited by Stubbie; 02-23-2008 at 03:34 AM.
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Old 02-22-2008, 04:50 PM   #2
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Two neutral bars


In my neck of the woods we have been required to run a 4 wire service since the 2002 code cycle. In your example Stubbie the AHJs here would fail me for the bonding screw in the neutral bar, only allowed to bond the ground to the can. Only neutrals can be hooked on the neutral bar and only equip. grounds on the ground bar.

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Old 02-22-2008, 05:07 PM   #3
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Two neutral bars


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Originally Posted by wire_twister View Post
In my neck of the woods we have been required to run a 4 wire service since the 2002 code cycle.
Can you explain this? I have never heard of a four wire (Hot, Hot, Neutral, ground) 1 phase service from the POCO before.

thanks.

Or are you talking about a feeder?
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Old 02-22-2008, 06:05 PM   #4
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Two neutral bars


Wire Twister

Look at the footnote **

This panel is the service equipment as noted in the drawing. Your area may require remote main disconnects for an mlo panelboard on or inside the dwelling. This would make the disconnect the service equipment. In which case you would have 4 wires from the disconnect to the mlo panel and you would not bond the neutral bar. Your main bonding jumper would be at the disconnect.

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Old 02-22-2008, 06:09 PM   #5
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Two neutral bars


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Wire Twister

Look at the footnote **

This panel is the service equipment as noted in the drawing. Your area may require remote main disconnects for an mlo panelboard on or inside the dwelling. This would make the disconnect the service equipment. In which case you would have 4 wires from the disconnect to the mlo panel and you would not bond the neutral bar. Your main bonding jumper would be at the disconnect.
In that situation where would the ground rods go? To the panel or disconnect?
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Old 02-22-2008, 06:37 PM   #6
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Two neutral bars


In that situation the disconnect is in an enclosure by itself no branch circuits originate there. You would bond the ground wire that you run to the mlo panel to the neutral lug at the disconnect. The image below shows why we do not bond the mlo panel in this situation. The service equipment is the first means of disconnect that the service entrance wires land on and that is where we bond neutral and ground. The water pipe bond and ground rods may also be required there. Rarely are these done at the sub-panel in the dwelling. Anything after the service equipment to the dwelling is 4 wires or 3 wires and metal conduit for equipment ground as shown in the image. You treat the load center as a sub-panel.

Am I being clear with my explanation?


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Old 02-22-2008, 07:05 PM   #7
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Two neutral bars


Crystal. Does the use of disconnects vary by POCO? Or, is it the installers preference?

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Old 02-22-2008, 07:52 PM   #8
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It varies by local jurisdiction,and what the service is brought in for...ie...farm pole, mobile home etc... it is becoming more common that service meters are accessible to the poco without going into backyards in populated areas. We have one municipality that requires the meter on the front of the house closest to the dwelling entry as possible. I wouldn't like that at all. You also have varying requirements for the water pipe bond in my area of authority it used to have to connect within 3 inches (no not 3 feet) of where the metal pipe entered the interior of the crawl space or basement. The NEC requirement is within 5 feet.
The new afci requirement in 2008 is being closely looked at by local authority as this is a huge expense to the contractor. Most think it is a crock, and I look for a lot of locals to exempt from this requirement.

I should also bring your attention to the disconnect bonding bushing and jumper on the conduit entering from the left (meter side) in the image this is another requirement with this set up.


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Old 02-22-2008, 08:05 PM   #9
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You are right stubbie, next time i will put my brain in gear first, it is friday and it was a long week.
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Old 02-22-2008, 08:10 PM   #10
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No problem Wire Twister. You're right it's Friday and we are entitled to a goof.....believe me I have made my fair share.
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Old 02-22-2008, 10:30 PM   #11
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Quote:
Originally Posted by junkcollector View Post
Can you explain this? I have never heard of a four wire (Hot, Hot, Neutral, ground) 1 phase service from the POCO before.

thanks.

Or are you talking about a feeder?
It is a feeder. I always buy the combo meter/disconnect and most time with several breakers for the outside.
4 wire from there into the MLO, seperate grounds and neturals.
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Old 02-22-2008, 10:43 PM   #12
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Two neutral bars


Wire twister. How far are you from Crawford?
I don't have my map handy.

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