[RE-wrenches] Grounding/bonding question for 200A main breaker service disconnect

[Mike Nelson]

It looks like there is a bonding screw just below where the bare equipment grounding conductor lands? That bonds that grounding lugs set to the panel enclosure. You can always do a continuity test from point to point to determine if they are bonded.

Michael D Nelson
MD Electric & Solar, Inc.
707-684-0064 mobile
707-884-1862 office
www.mdelectricsolar.com
www.facebook.com/mdelectricandsolar


> On Dec 29, 2016, at 3:31 PM, August Goers <august at luminalt.com> wrote:
> 
> Hi Rebekah,
>  
> If in doubt, it won’t hurt to run a bonding jumper from the neutral block to the new ground bar. Check out NEC 250.92 if you haven’t already.
>  
> That neutral block you show in your picture clearly has an insulating gasket behind it and it is really hard to tell if the screw is intended to ground it to the can or not.
>  
> We have to do a bonkers amount of grounding here in San Francisco so have become very familiar with all the little ins and outs of grounding (at least how San Francisco wants it). I like the Soares Book of Grounding as a visual backup to the NEC:
>  
> https://www.amazon.com/Soares-Book-Grounding-Bonding-2014-NEC/dp/1890659657
>  
> Cheers,
>  
> August
>  
> From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Rebekah Hren
> Sent: Thursday, December 29, 2016 2:40 PM
> To: RE-wrenches
> Subject: [RE-wrenches] Grounding/bonding question for 200A main breaker service disconnect
>  
> Hi Wrenches, 
> Is anyone familiar with the type of main disconnect shown in this picture? I need to figure out if the GEC is bonded to the box or not. A supply side connection has been made in the box, and the only grounding for the PV system is via the green EGC on the new terminal strip.  I am inspecting this as a third party, and did not perform the installation. 
>  
> I cannot tell if the GEC (the bare copper) is bonded to the box via the (apparently) isolated terminal where the neutral and main panel EGC (the bare aluminum) are landed. 
>  
> The green wire on the grounding terminal at the bottom left is the EGC running to the supply-side connected PV system AC fused disconnect, but the PV system will not actually be grounded (um, at all) unless the GEC is bonded to the box through that black plastic neutral block, which appears to be isolated with cardboard. There is no other connection to physical earth except the bare copper GEC. 
>  
> Checked with the meter and got continuity from the green to bare wire, but that could be because the bare aluminum EGC is touching the box in multiple places.
>  
> It may be that the GEC is bonded via a back-mounted screw to the box, but I just can't tell what's going on with this design or what is supposed to be happening. That tab to the right of the bare copper GEC does not actually touch the terminal above it as you can see from the second picture, unless it is a connection in the plastic. 
>  
> <image002.jpg>. 
>  
> <image004.png>
>  
> Thanks for any insight!
> 
>  
>  
> Rebekah
>  
> --
> Tel: 336.266.8800
> NABCEP Certified Solar PV Installation Professional™ 091209-85
> NC Licensed Electrical Contractor
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