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

[August Goers]

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.



[image: Inline image 1].



[image: Inline image 3]



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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