EMT - UL Heads Up [RE-wrenches]

[Matt Lafferty]

Brother Bill wrote:

> I would take anything that a Carlon representative said with a grain
of salt.
> They are in the business of saying that their product is as good or
better
> than EMT. Show me an unbiased engineering study done on the two and
> we'll talk. Waterfront environments aside, most of California has
extremely
> low corrosion rates, and I would put my bets on EMT any day. Water
> tightness is a hoax that I hope UL and others get away from. Water
lives in
> outdoor conduit systems regardless of their composition. That is why
all
> conductors must be wet rated. (SNIP)

> It doesn't make a lot of sense to me. I believe that outdoor boxes and
wiring
> systems need drains to allow water to escape. Putting a better
watertight
> fitting on a conduit is going the wrong way in my book.

All:

Hear, HEAR!

Bill is on my page on this one... Your's, too, I hope.

I don't consider PVC to be appropriate for horizontally run, elementally
exposed applications.  In fact, every single time I can remember pulling
conductors out of underground PVC conduit, the conductors were wet if
installed for a year or more.  Something to think about....

I don't know if my experiences come from UV or heat-related exposures,
or a combination thereof.  What I do know is that I have seen and
replaced too many exposed horizontal PVC conduit installations with
sagging runs, split fittings, disfigured shapes, separated connections,
and exposed conductors (previously inside the conduit).  These
observations are not specific to PV (none have been), nor are they
specific to rooftops (most weren't).  Virtually all of them were
strapped and supported "per Code" or better!  Didn't seem to matter if
the conduit was painted or not.  No observation on my part was ever made
that paint or other external chemicals led to these conditions.  Most
had THHN conductors inside.  Depending on the duration of exposure to
the elements, some of the conductors had split / separating insulation.
One installation actually had a disposable diaper wrapped around the
conduit break with PVC electrical tape securing it to the conduit.  It
failed.  It was NOT exposed to direct sunlight, by the way.  (I kept it
as an example for a few years, but it's disposed of now....Wish that
were during the day of digital cameras so I had something besides by
memory to show you...)

As far as EMT fittings and UL Listing Standards goes, my take on it is
generally this: UL decided to take the "product based fix-it method" as
opposed to relying on the "installer / inspector based method".  (Funny
to me that 1-1/4" - 4" fittings weren't submitted / didn't pass the UL
testing... Gotta use Rigid Conduit or what?  Union influence?
Hmmmmmmmmmm!!!!!!!  This is a nationwide issue, by the way.  NOT just a
CA issue...)

It all boils down to the guy/gal installing whatever it is.  Could be a
2x4 wood stud or it could be a 600V conductor.  Their appropriate
selection and installation methods of selected materials for an
application ultimately determines the long-term reliability and safety
of the "system" they are installing.  This applies to everything... RE,
electrical, or otherwise.  I support (Back when I had actual control
over such things, I required!!!!) drain holes in J-boxes and any other
termination enclosure.  I only ran into one Inspector who raised the
issue of "this isn't how it was listed"... That guy was easily convinced
of the value using real-world examples based on his own experience.  A
small price to pay, in my book. 

Apparently UL noticed (or was made aware) that water / moisture is often
found inside J-boxes, etc. (Like... Geeee.... Duh!  Like, since the
beginning of conduit-time... What did you think would happen????)  In
above-grade, non-flooded applications, two primary sources for moisture
exist inside raceways.... One is "direct, beating rain".  The other is
condensation.  

Ambient humidity enters raceways via numerous ways.  (A NEMA 3-R
enclosure does not prevent intrusion of ambient humidity) I'll leave it
at that.  As heat from different sources affects the internal
temperature of the raceway, moisture migrates through the raceway
system.  Under certain conditions, humidity is actually attracted and
"drawn" to the interior of the raceway.  As moisture migrates, it
aggregates or is "trapped" in different areas, generally larger surface
area enclosures or "high to low elevation" traps.  Physical fact.  If
these enclosures are not allowed to drain, the moisture condenses
into.... Of all things.... Water!  This builds up over time if it's not
allowed to escape.  Therefore the drainage holes. (I use a 3/16" bit for
these, personally.)

Long story short.... I hope everybody's using the best information they
have available and the best practices & judgement regarding product
selection and installation methods available for each of their projects.

I must say that it's nice to see on-list discourse on something after I
post... I've come to think that nobody reads my stuff!!!!  LOL (No
feelings hurt.  I'd have to have feelings before they could get hurt...)

I do have to ask Mo R and others that were aware of this why they didn't
consider this to be relevant to the list????  Nothing personal.  Just
hope that what we're here for is not lost in the fray.  

Two Cents and Hammock Dreams!

Matt Lafferty
Universal Energies Institute
mlafferty at universalenergies.com
(916) 422-9772
(916) 628-7694 Cell
(916) 914-2247 Fax
www.universalenergies.com

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