Rotary phase converter: local ground or all the way to the panel?
According to rpseguin :
I know that I could run a ground line to the panel AND run a local
grounding rod, but is it a bad idea to just do a local ground?
Yes, for the reasons expressed by others.
What gage wire for a 20HP RPC, but the main/biggest load/machine will
be a 10HP spindle and a couple of 2HP machines, never all at the same
time? ($ signs get much bigger with the wire gage/diameter :-)
Remember that there are losses in the RPC. A 10HP spindle actually
loaded to 10HP (as opposed to an unloaded 10HP motor) is going to
present something more like 12-13HP on the RPC. So, you're going to
have to factor in 20-30% losses.
Secondly, yeah, wire is expensive. You may wish to consider
using aluminum instead. Done correctly (to-code connectors and
conductive grease for the application), it's just as safe, to-code,
and a lot cheaper.
When I installed the 100A subpanel to my detached garage (100'
of burial), I saved something near $300 by using aluminum instead
of copper, and the inspector was perfectly happy with it - despite
catching the electrician forgetting the grease on the subpanel end... ;-).
--
Chris Lewis,
Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.
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