Neutral Bar Full Options

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  #1  
Old 08-30-06, 06:51 AM
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Unhappy Neutral Bar Full Options

I am working on the installation of a generator transfer switch with an integrated subpanel to feed 16 isolated circuits which will be on standby power. This is a DIY kit from the manufacturer.

This is a proprietary design by the generator manufacturer with no expansion capability (i.e., you cannot buy/install an additional ground bar, etc). In fact the unit is largely made of ABS plastic rather than metal. About all you can do is configure the circuit breakers as you need them within the load capacity of the genset.

The problem I have is that the included neutral bar is very small. The manufacturer instructed not to land all neutrals from the main panel into the transfer switch subpanel and cited 1999 NEC as well as UL compliance permitting this. The small included neutral bar was only for GFCI and AFCI breaker usage. The AHJ overrode the manufacturers installation manual and cited 2002 NEC requirements to land the neutrals for all protected circuits into the transfer switch panel. I was told by the AHJ 110.3(B) does not apply in this situation.

Fortunately the selected circuits mostly have shared neutrals but due to the design there are not enough screws as needed - am short only two free spaces! As they are rated for one wire only I am looking for any options to mitigate this situation short of removing circuits from the configuration.

Again, this is device is not expandable according to the manufacturer. There is no ground bar provision as it uses a ground lug bolt instead and a lead to the main panel ground bar. In the past it was code permissible (at least the AHJ approved here) to splice (via wire nut) two manufacturer integrated neutral leads from a AFCI or GFCI breaker together and run to a single neutral bar screw if the included breaker lead was not long enough to reach the neutral bar.

Does anyone know if there is an NEC article that I could reference as to whether this approach is still, or ever was, permissible? Basically looking for any options to get around a full, non-expandable, neutral bar given the curve ball the AHJ threw on landing all the neutrals.

Thanx,
 
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  #2  
Old 08-30-06, 07:18 AM
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Honestly, I'd ask the AHJ what he suggests. If the transfer switch has no approved add-on neutral buss bar, and the AHJ wants you to land all of the neutrals regardless of the number of lugs available, you've got a problem. Would the AHJ be OK with your use of a add-on buss bar solution that isn't approved for that particular transfer switch? I'm sure you could find some way to add in an extra buss bar, just not a listed/approved way for that piece of equipment. While I wouldn't like doing that, if the AHJ was OK with it, I'm sure I could fit an extra buss bar in there somewhere.

Hate to say it, but your only option might be to get a different switch.
 
  #3  
Old 08-30-06, 07:25 AM
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I agree that you need to speak with the AHJ to see what they will approve. You may be out of luck and unable to use this transfer switch if the AHJ won't accept any work arounds.

As for two neutrals wire nutted together and then attached to the ground bar, this is not a good idea and perhaps it is unsafe. Two 14 gage neutrals for 15 amp circuits would need to be attached to a 10 gage neutral for 30 amp capability. For two 12 gage circuits, an 8 gage wire. I don't like this solution at all.
 
  #4  
Old 08-30-06, 08:30 AM
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Are you saying that you moved the individual romex wires from the existing panel to the new generator panel, but somehow tied the neutral wires into the main panel?

How is this supposed to be done?
 
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Old 08-30-06, 08:46 AM
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Jeff,

I recently researched generator transfer panels. I didn't buy one, but instead opted for a main breaker interlock kit, but I did learn about them.

One panel requires that you install it by running only the hot wires for your desired circuits from the main panel to the generator panel. At the main panel you leave the neutrals connected as they are, to the neutral (or neutral/ground) buss. The only exception is for AFCI and GFCI circuits.

One neutral and one ground run from the main panel to the generator panel. The ground connects to the generator ground (and of course the metal transfer panel), and the neutral connects to the generator neutral and to a small neutral buss used for the neutrals for AFCI and GFCI breakers.

I do not know if drshock is talking about this panel or not, but he/she could be.
 
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Old 08-30-06, 10:44 AM
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"One panel requires that you install it by running only the hot wires for your desired circuits from the main panel to the generator panel. At the main panel you leave the neutrals connected as they are, to the neutral (or neutral/ground) buss. The only exception is for AFCI and GFCI circuits. "

I dont see where there is a problem with this as long as the neutral from the generator, (and it would have to be a large one) is in the same raceway as the hots. (bunches of little ones)

If done a different way, inductive heating would be a real problem.
 
  #7  
Old 08-30-06, 11:03 AM
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Actually, the neutral wire only needs to be sized to the rating of the generator, which could be 20 or 30 amps. Yes, it is run in the same conduit as the hot wires and the ground wire.
 
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Old 08-30-06, 11:26 AM
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This panel is made by the Generac corporation for use with their 16KW genset units.

It uses a 24inch nipple conduit to evade pipe fill and de-rate requirements and you route a harness of some 30 conductors consisting of 14AWG, 12AWG, 8AWG, 6AWG and 4AWG thru it over to your main panel. In then further routes a 1 inch metal conduit 30 feet over to your generator output and includes an 8AWG ground, 6AWG (90 degree rated at 75A) genset output and four 18AWG power supply control lines (from the genset 12VDC output) within that same raceway (apparently also allowed via 725.26(B)(1)).

Anyway you run the 4AWGs to a 70A breaker in your main panel and land the 4AWG neutral and wire nut all the hots of various gauges in your main (this splicing is allowed by NEC for exisiting construction retrofits such as this according to my AHJ as long as 312.8 is in compliance as well) to the harness leads coming thru the two foot nipple back to matching amperage breakers in the transfer switch subpanel. It's an afternoon job at worst.

Unfortunately for me this is the design that does not support landing the neutrals that another poster cited and in my county 2002 NEC prevails here requiring them to be landed.

Overall though I found the Generac product very easy to install and well thought out. The only downside is that they need to update their offering to meet the 2002, or even 2005, NEC. Something easily done with updated instructions and a larger neutral bar.

Thanx,
 
  #9  
Old 08-30-06, 11:33 AM
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What article did the inspector site?
 
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Old 08-30-06, 04:50 PM
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Originally Posted by racraft
Jeff,

I recently researched generator transfer panels. I didn't buy one, but instead opted for a main breaker interlock kit, but I did learn about them.
How do you like the interlock device?
 
  #11  
Old 08-30-06, 05:53 PM
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I prefer the interlock. With it I am able to use any combination of breakers I want on generator power, with the exception of the breaker directly below the interlock. So I made sure that the breaker I cannot use with the generator is something I will never use on generator power.

This means I can, for example, if I want, power my garage door openers. I might want to do this to say position the trolley in the down position, so I can lock the doors.

With a transfer panel I would be limited to only the circuits I moved to the generator panel.
 
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Old 08-30-06, 06:17 PM
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That's definitely nice, and a LOT cheaper than getting a 200 amp DPDT transfer switch.
 
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Old 08-30-06, 10:40 PM
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I'm curious also to see what article the inspector is citing that makes 110.3(B) not apply.

The panel you are talking about is a UL listed assembly and the AHJ can't just decide he is going have you wire it his way instead of the way the manufacturer intended it. This will void the UL listing of the unit.

Is the AHJ going to give you something in writing to say he is responsible for making you void the listing ?

This generator panel looks like a sub panel but is still a transfer switch and 1 neutral large enough to handle the load is all you need and is what is intended by the manufacturer. (#4 Neutral is alot more than you need for a 70 amp feeder)

I honestly think this inspector is confused and I would ask him to quote you a code article that prohibits this or go over his head to the chief inspector.
 

Last edited by rich3236; 08-30-06 at 10:59 PM.
  #14  
Old 08-31-06, 04:50 AM
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In the inspection report the AHJ cited four articles giving him the authority to override the UL listed installation instructions.

210.4, 300.3(B). 300.20. No 702 exemption noted for any.
 
  #15  
Old 08-31-06, 05:59 AM
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My opinion, which means little since I am not the inspector, is that those articles do not apply here.

I think you need another inspector.
 
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