On Wed, 12 Jun 2019 11:14:35 -0500, Terry Coombs
wrote:

On 6/12/2019 8:48 AM, wrote:

Â* Done is done , I have bonded the ground/neutral in the sub panel and
added a ground rod out in the shop .

snip...

I agree using the 3 wire system and bonding the neutral and ground is the most practical solution. But be aware, if that third ground/neutral wire should fail open, there will be a dangerous condition in the outbuilding. Everything that was ground, can become energized.



mark



Â* The likelihood of that 3/0 cable failing is very very slim ... I'll
also be bonding the metal frame of the shop to the panel , it has some
serious ground contact , including either 6 or 8 5/8" rods a couple of
feet long driven thru the bottom member into the ground before I poured
the concrete . I've been running stuff out there with a 3 wire
ungrounded neutral bonded supply for 5 years or so , never had a problem
. That was with lighter wire , part of the install of the new panel
included running the 3/0 aluminum cable all the way to the shop to
replace that section of smaller wire .

If there is a total of 10' or more of steel in contact with that
concrete footer you have a Ufer (concrete encased electrode) and that
is far better than the rods you drove. In fact with a Ufer, you don't
even need the rods. You should be using a #4 or larger to connect the
Ufer, Rods only require a #6. That should tell you something right
there. If I was doing it I would have run another #5 rebar around the
footer, tying all of the down rods together and then you have serious
contact with the concrete and a stronger footer.