EMT - UL Heads Up [RE-wrenches]

Mon Mar 15 18:35:26 PST 2004

Hello Matt,
2 word solution for water in boxes. Weep Holes.
Best regards,
Joel Davidson

----- Original Message ----- 
From: "Matt Lafferty" <mlafferty at universalenergies.com>
To: <RE-wrenches at topica.com>
Sent: Monday, March 15, 2004 6:08 PM
Subject: RE: EMT - UL Heads Up [RE-wrenches]

> 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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> 
> 
> 

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