Sub Panel Grounding Question

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Old 01-25-08, 11:32 AM
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Sub Panel Grounding Question

I added a sub panel for the sole purpose of increasing my number of circuits. It is 1' away from my service panel.

I have the grounds and neutral separated. The sub-panel ground is connected to the main panel ground outside of both panels as the bare ground is going to the exterior ground rod. I used a heavy duty wire connector given to me years ago by POCO. I measured the resistance and it is good.

Is this acceptable? I cant imagine that I would have to run a separate bare ground outside to the rod. The connector is securely fastened to the existing ground wire and will not separate under a fault condition.
 
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Old 01-25-08, 11:44 AM
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No, this is wrong. The ground from the sub-panel must go into the main panel and connect to the combined ground/neutral buss.
 
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Old 01-25-08, 11:56 AM
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Only subpanel in detached buildings get connected to ground rods. Subpanels in the same building connect to the main panel ground/neutral bus.
 
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Old 01-25-08, 06:25 PM
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sorry not starting a feud, but cod eonly requires the equipment grounding conductor to be connected to the electrode system as long as its the same electrode system, ireally could go on and on this subject(grounding and bonding) could update on detached buildings as well
Originally Posted by ibpooks View Post
Only subpanel in detached buildings get connected to ground rods. Subpanels in the same building connect to the main panel ground/neutral bus.
 
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Old 01-25-08, 06:42 PM
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480, try explaining that so it makes some sense. All grounding systems must be bonded in any given building so it is the same grounding electrode system.

what ibpooks posted is correct
 
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Old 01-25-08, 11:53 PM
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Section 250.130(A) requires the equipment grounding conductor (EGC) be connected to the grounded service conductor (service neutral) and the grounding electrode conductor (GEC).

This EGC is connected to the GEC, which is connected to the service neutral.
I donít see anything requiring the connection be made at a bus.
 
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Old 01-26-08, 04:46 AM
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it depends on how you want to read that section.

Section 250.130(A) requires the equipment grounding conductor (EGC) be connected to the grounded service conductor (service neutral) and the grounding electrode conductor (GEC).

It does not say that it can be connected to either and via the bond with the third conductor it is adequately bonded. It says specifically that the EGC is to be bonded to each of the other 2 conductors. The only place this can take place is in the service disconnect.


You apparenlty read that differently?

I can also tell you in actual practice that the inspectors in my area require it to be in the service disconnect as well.
 
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Old 01-26-08, 02:57 PM
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yes you are correct without a doubt in that sense(that article), but again not starting a feud or competing. i will stay with my quote and will not touch the question from nap leave that 1 for other electricians. ty
Originally Posted by nap View Post
it depends on how you want to read that section.

Section 250.130(A) requires the equipment grounding conductor (EGC) be connected to the grounded service conductor (service neutral) and the grounding electrode conductor (GEC).

It does not say that it can be connected to either and via the bond with the third conductor it is adequately bonded. It says specifically that the EGC is to be bonded to each of the other 2 conductors. The only place this can take place is in the service disconnect.


You apparenlty read that differently?

I can also tell you in actual practice that the inspectors in my area require it to be in the service disconnect as well.
 
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Old 01-28-08, 08:41 AM
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The sub-panel is connected to the disconnect ground wire. The only difference is that the connection is not inside the main panel. The connection is outside of the panel with a heavy duty fastener.

I know it is a matter of code but the way I have it connected is serving the same purpose. I imagine that the NEC wants all connections inside of the panel for a very specific purpose (ie. possibly to protection from any arc that may occur during a ground fault?)

This panel was originally added under pre-2000 code so it was approved without any ground wire at all. I was just adding a ground wire from the sub-panel.
 
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Old 01-28-08, 08:56 AM
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If your sub panel had no ground wire at all then hopefully the ground buss and neutral buss were bonded. Once you add a ground wire you needed to separate the two and make sure they are NOT bonded at the sub panel at all.

I maintain that your installation is improper. Put the ground connection IN the main panel, where I believe is the only place it is legal.
 
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Old 01-28-08, 10:59 AM
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Thanks Racraft,

I will do that ASAP.
 
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Old 02-01-08, 07:56 AM
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Wink QO load center bond seperations

Main Panel
Square D 200 amp QO (maxed out) bare bond wire out to ground rod below mainpanel
(Has GFCI's for pool and Spa and dock power currently)

needed a subpanel for two reasons
ONE installed jacuzzi tub requiring TWO seperate 110 V GFCI circuits
Two Future pool heater will also require breaker down the line

Proposed Subpanel
Distance from main = 1 foot

I selected a load center Square D 6/12 100amp #qo612l100rg (Main lugs)
and purchased a seperate ground bus bar for same load center

I plan to remove from existing main panel a single 25amp two pole breaker
running an airhandler now and adding in its place a single qo2100cp 100 amp
2 pole breaker in its place to feed the load center

I am going to service this panel with (4 wires via 2" pvc conduit)

(Qty 3) #2 Copper (600 volt AWG 2 33/62 mm2 cu type mtw or thwn-2 or thhn 3R)
one for each pole and the 3rd for nuetral
(qty 1) #6 bare copper ground wire to the load centers isolated ground buss bar
I intend to fed this from within the main panel off the combined
nuetral/ground buss bar to the load center ground only bar
unless someone tells me otherwise!

If I have read everything in this post correctly
the subpanel in the same building

Should not be bonded to a ground rod

should have the ground and nuetral buss bars completely
seperated in the load center sub panel

I also plan to use the load center main lugs to feed service
to this cabinet (Allowing the 100 amp feeder breaker in the main
to serve as the sub panel disconnect)
(I think this is Fine to do and certainly saves 1 pricey breaker?)


I plan on pulling over (mainpanel to load center)
the 2pole 25Amp air handler circuit and
some light duty general lighting into the new load center
Then placing my two new 20 single pole GFCI's back into the main
where the general duty lighting circuits were removed

*Adding GFCIs to the load center would be easier but I lack a comfort
level of how GFCI's may work in the unbonded sub panel as opposed to the main
especially while I soak away my troubles in the new installed spa bathtub <Grin>


My first main questions is
How do you keep the nuetral and ground buss seperate when
adding the seperate ground bonding bar with supplied screws
into this model load center without creating a path back through
the load center to the installed nuetral bar (negating seperation )

I do see in the QO load center literature a long screw for bonding
inserting through the nuetral buss bar
(Which I have no plans of inserting at current)
I might assume without it installation is good for a subbie panel
but why assume with you guys out there
Quick answers for the taking !!! solves much time and troubles later

and secondary do any of you guys see a major point or correction on my proposed
actions at this point


Thanks

Charlotte ; o )
 
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