"Ivan Vegvary" wrote in message
news
Getting things arranged in my new (new for me) shop. It has 3 phase
power,
therefore the questions.

1) Do I simply run 3 wires to the machines (lathe, mill, grinder & surface
grinder) and let the conduit be the ground, or do I need a seperate ground
wire. The existing building has a few 3ph outlets (in conduit), but no
ground wires.

Using the rigid conduit (either EMT or the threaded style) as ground does
meets code. Code says this is discretionary - run a separate ground wire
inside the conduit if the location puts the conduit at risk from corrosion
or mechanical damage, or if you feel like it.

If part of the conduit is "flex" there are restrictions on the length and
the current rating for its use as the grounding conductor. The flex
connectors aren't as secure as EMT so it's a good idea to either not use
them at all or to run the separate ground wire.

2) My machines will be out in the middle of the floor. Do I simply dangle
a
conduit from the roof framing (15 ft. above), or, do I install a post upon
which the conduit will come down? Do I do this once for each machine?
Somebody must have a clever solution to this situation. I don't want to
cut
up my slab and install wires below.

The conduit needs to be fully supported. You'd need a post to drop it all
the way down from 15'. The more common thing is to install cord drops.
Install a box at the ceiling with a 4 conductor SO cord attached at the top
via a cord strain relief, with a L15 twistlock female cord connector at the
loose end.

If you make the cords long, they can run horizontal some and then drop down
wherever.

Using the plug and receptacle means you don't need a separate disconnect
switch.

Bob