EMT - UL Heads Up [RE-wrenches]

[Bruce Geddes]

Hi All,
            Following this thread with interest.

Being in New Zealand complete with ozone hole exposes us to some of the
highest UV levels to be found.  PVC conduit is used widely here but it is
stamped UPVC for UV stabilised.

I have seen installations exposed that are older than 20 years and the
conduit is intact.  The surface does go faded and a powdery layer forms but
it is only very thin.  The underlying material is good.  We use two colours,
grey and orange and both behave the same.  The biggest problem is impact
damage as PVC is relatively brittle.

As pointed out in other posts if it is not supported frequently the conduit
will sag between fixings.  If there is enough of this sagging the glue
together joints can seperate if not glued properly.

Condensation is an issue and even the moistureproof boxes I use on rooftops
still develop some moisture inside after years of use.  I now drill small
drain holes at low points and ensure that there are low points before every
termination or penetration.

I use rigid for the main runs and have a length of flexible jointed on to
run up to PV junction boxes.  This allows the panels to be tilted and lay
over for maintenance work.

Metal conduit has not been widely used here for decades.  I know that this
is not the USA and your NEC is different, but electricity is electricity.
Incidentaly we use 230/400VAC 50Hz.

So at the end of the day PVC conduit has a place and can do the job.
Longevity has as much to with installation techniques as with the material.

Just my NZ$0.02 worth  (US$0.013)

Bruce Geddes
PowerOn

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