[ale] Low voltage work in GA

[Michael H. Warfield]

On Tue, 2012-07-31 at 14:36 -0400, mike at trausch.us wrote:
> On 07/31/2012 02:15 PM, Greg Clifton wrote:
> > A related question occurs to me. I would assume that the grey
> > (PVC?) electrical conduit would not be allowed for plenum installation,
> > rather you would have to use the thin walled metal, no? Otherwise,
> > wouldn't  putting PVC cable in PVC conduit defeat the purpose of using
> > conduit so as not to get gassed by the Chlorine content of the PVC when
> > the fire starts?

> I am pretty sure that insofar as conduit is concerned, you must use
> either EMT or rigid conduit in commercial installations, and rigid
> conduit is typically required for things that run voltage greater than
> that which is used for communications and data lines.

Huh?  EMT is "Electrical Metal Tubing" - AKA rigid conduit.  Basically
the thin-walled tubing you use with a varied of connectors into boxes
and what not.  The 1/2", 3/4", and 1" thin walled pipe you get in the
electrical department of Home Depot and Lowes.  It's perfectly fine for
110VAC/220VAC and even some 208 3-phase.  If you get much above 1" EMT
(lots of wires or large gauge / high current) or your dealing with
higher voltages (I've dealt with 440 3-phase commercial stuff in the
past - not fun) then you're going to be using the heavy gauge pipe that
screws into screw fittings or uses locking bushings directly on the
threaded pipe and you could almost use as pressurized water pipe.
That's what you use for service entrance masts and wires that are rated
in mcm cross section rather than gauge.

What are you referring to when you are referring to EMT?  They use EMT
for 110VAC branch wiring in commercial all the time unless things have
radically changed since I worked as an electrician.  When you say "and
rigid conduit is typically required for things that run voltage greater
than that which is used for communications and data lines" that seems to
imply you can't use EMT for that and that doesn't make sense to me, the
way you phrased it.

You can also run 110/220 through flexible metal conduit as well, though
those are normally limited to hookup runs to equipment like HVAC gear.

Regards,
Mike

> In a house, you can get away with PVC or plastic conduit.  Code is much
> more strict with regard to commercial buildings.  Also, the conduit must
> be grounded.
> 
> There are some exceptions for raceways, but I don't intend on using such
> things.  Personally, I am a fan of putting things in a way or using a
> metal conduit that will more-or-less blend in once painted.
> 
> 	--- Mike
> 
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-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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