Residential panelboard questions

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silverbk

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I am having a dispute with another electrician about panelboards.

In a residential panelboard/service disconnect. Can you land equipment grounds and neutrals to the neutral bus? They are bonded together.

I would prefer to see all neutrals on the neutral bus and all equipment grounds on the equipment ground bus and possibly if you have overflow some neutrals on that bus also. I know they are bonded together and that is probably safe either way, but I am interested in what is being enforced and what is the letter of the code on this.

My colleague says there is nothing in the code that prevents you from landing equipment grounds on the neutral bus. I have referred him to the actual label in the panel which identifies the bus on the right as the neutral and the one on the left as the equipment/neutral bus.

I'm thinking 408.40 is the relevant section, any comments?
 
There is usually only one bus in these panels to begin with. The EGC's and grounded conductors can all terminate on the common bus.
 
silverbk said:
..... I have referred him to the actual label in the panel which identifies the bus on the right as the neutral and the one on the left as the equipment/neutral bus....
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Is that a panel that allows you to remove the jumper bus between them, making one a grounding bus and the other a grounded bus? Seems to me GE and Seimens have that option.
 
The panel is a Murray 200 Amp. It has two buses that can be bonded together by placing a metal jumper under a screw.

It also has provisions to add additional equipment grounding buses for a sub panel setup.
 
I'm thinking 408.40 is the relevant section, any comments?
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The last paragraph of 408.40 requires you to use a grounding bar and keep the equipment grounding conductors and the grounded conductors separate unless interconnection is permitted or required by Article 250. So if this is the service disconnecting means then interconnection of the EGC and the grounded conductors is required and it is permissible to install both grounded and EGC's on the same bar.

Chris
 
Silver, let's put it this way: the neutrals must land on the same bus(es) that the supply neutral lands on, and cannot depend on the enclosure for continuity. The EGC's, on the other hand, may use the enclosure's conductivity.

Of course, in the case of a 4-wire supply, there will be no bonding. In a panel with the bond in place, the neutral bus(es) may indeed be used to land the EGC's. In fact, when using a bonded setup, I'll remove unused buses.
 
silverbk said:
I am having a dispute with another electrician about panelboards.

In a residential panelboard/service disconnect. Can you land equipment grounds and neutrals to the neutral bus? They are bonded together.

I would prefer to see all neutrals on the neutral bus and all equipment grounds on the equipment ground bus and possibly if you have overflow some neutrals on that bus also. I know they are bonded together and that is probably safe either way, but I am interested in what is being enforced and what is the letter of the code on this.

My colleague says there is nothing in the code that prevents you from landing equipment grounds on the neutral bus. I have referred him to the actual label in the panel which identifies the bus on the right as the neutral and the one on the left as the equipment/neutral bus.

I'm thinking 408.40 is the relevant section, any comments?
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I agree with the others. If this your main service rated panel, then you should not be floating the neutral.
 
LarryFine said:
Silver, let's put it this way: the neutrals must land on the same bus(es) that the supply neutral lands on, and cannot depend on the enclosure for continuity. The EGC's, on the other hand, may use the enclosure's conductivity.
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Is that current or 2008? I was thinking that was part of the new rewording, always implied/intended, but not spelled out in previous codes.
 
250.24(A)(4) permits one to terminate the grounded and equipment grounding conductor on the same terminal in the panel if it is the first means of disconnect for the service.


I do not see any issue with this type of setup at all.

Remember we perform single point grounding at most premises wiring in the US of A.
 
360Youth said:
Is that current or 2008? I was thinking that was part of the new rewording, always implied/intended, but not spelled out in previous codes.
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Yes this is a change for the 2008 NEC.
Also, only one grounded conductor is allowed per terminal. More EGC can connect to one terminal depending on how its listed.
 
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