On 12/9/17 4:45 PM, Terry Coombs wrote:
Â* The old panel in my shop is giving up , the old aluminum buss bars
are just getting too bad to continue using it . So Thursday while we
were down in Memphis I picked up a new box - 20 slots/20 ckts/100 amp
in-feed breaker (also gets a 100A feed breaker in the main panel)Â* . It
has 2 neutral/ground connection strips , connected by a link at the
bottom and not bonded to the enclosure . I plan to move the ground strip
from the old box and use both of the ones in the new for neutrals .
Â* Here's where I'm not sure what I want to do - the supply from the
main panel in the house is 3 wire 2/0 aluminum . I'm not sure at this
point how I want to handle the neutral/ground issue . I'm inclined to
let the neutral float and drive a separate ground rod for the shop .
Ground will be bonded to the enclosure . I don't think that will give me
any ground loop issues , but there may be a problem with a difference in
potential between the ground and neutral . I guess I could just let the
neutral act as ground too , they are bonded in the main panel - oops ,
no they're not bonded in the main panel , the only place the neutral is
grounded is up on the pole at the transformer . Main panel ground is a
standard 8' ground rod and it's bonded to the enclosures (meter base
too) . The other issue I have is what to use to connect a copper pigtail
to the end of that 2/0 al wire . The al wire may be too large in
diameter for the in-feed breaker in the new panel .
Â* --
Â* Snag
It's best to get the neutral and earth at the same potential
especially if you have
livestock. I bet you already know that. I've seen stories of animals
that won't drink or
cows that won't milk because of ground loops.
I like this pictu
https://www.bing.com/images/search?view=detailV2&ccid=dUIWgCvZ&id=FB485FA3F206 ECBA07A9C7C34BCCC4EE2FC41E8A&thid=OIP.dUIWgCvZFit3 kBa07xgd_AEsDh&mediaurl=http%3a%2f%2fwww.mikeholt. com%2fgraphics%2ftouch.gif&exph=480&expw=640&q=ear th+bonding+++mike+holt&simid=608016879678589222&se lectedIndex=1&ajaxhist=0
or
http://alturl.com/5wr5f
There's a chart in this article showing typical earth resistance:
http://www.utilityproducts.com/articles/print/volume-16/issue-3/product-focus/safety-products/step-and-touch-potential-awareness.html
or
http://tinyurl.com/y7zrbf5k