Thread sealant on service mast

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Dansos

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We do not do a lot of service masts in our area (mostly PVC and POCO connects to structure). When installing the rigid pipe into the meter hub, does that section of thread need a special sealant? NEC is pretty vague. Is this up to POCO?
 
Burndy Penetrox or equal. Hub is usually die-cast zinc or aluminum. Can't hurt. I've used it on aluminum rigid that was buried and after 25 years the coupling came apart like it was new when I had to do a repair because a tent guy won the lottery and hit it dead on.

-Hal
 
A tapered pipe thread joint properly torqued will be water tight enough for a zero pressure environment without any kind of sealant.
If you do use sealant, either dope or tape, you do not have to worry about losing electrical connectivity since there will still be good metal to metal contact on part of the thread surface.
 
Not suggesting a sealant. Pipe dope or teflon tape- we ain't no plumbers. If nothing else I like to lube the threads with a little oil just to make it easier to make it up. For dissimilar metals I like to use Penetrox because it's an anti-oxidant. You just might want to get it apart one day. Usually have it on the truck anyway.

-Hal
 
According to the white book pvc is not tested for use in a threaded hub just rigid. I have never seen it turned done but nonetheless it isn't compliant.
 
Here is the white book wording

This category covers metallic and nonmetallic conduit fittings, such as
connectors, couplings, conduit bodies, short-radius conduit bodies, expansion
fittings, locknuts and sealing (liquid-tight) locknuts for use in the
assembly of nonmetallic and metallic wiring systems. Also covered are
fittings used to provide a transition between metallic and nonmetallic wiring
systems. All fittings are intended to be installed in accordance with
ANSI/NFPA 70, ‘‘National Electrical Code’’ (NEC), and are intended for
installation and use in accordance with the following information and the
limitations specified in the appropriate conduit or tubing category.
Some of these fittings are also suitable for use in certain hazardous (classified)
locations where unclassified locations fittings are permitted in
Articles 501, 502, 503, 505 and 506 of the NEC.
This category also includes metal bushings for use in conduit and insulating
bushings for use on conduit inside boxes, gutters, etc.
The individual certifications for each connector used with nonmetallicsheathed
cable may have details about the size and number of the
nonmetallic-sheathed cable it will secure.
All male threaded fittings and nipples have only been investigated for
use with locknuts.
Fittings with internal female threads (e.g., hubs, conduit bodies, couplings)
have only been investigated for use with threaded rigid conduit.
Click to expand...
 
Dennis Alwon said:
According to the white book pvc is not tested for use in a threaded hub just rigid. I have never seen it turned done but nonetheless it isn't compliant.
Click to expand...

The OP wasn't clear on always using PVC. I also saw he mentioned rigid pipe which I replied to, sorry I didn't make the distinction. I agree with Dennis on using a male adapter. You would think that due to the necessity of using conduit fittings with WP boxes the manufacturers would make their products suitable for the use.

-Hal
 
There is a difference: WP boxes are designed to reject water, while exterior enclosures are designed to drain.
 
LarryFine said:
There is a difference: WP boxes are designed to reject water, while exterior enclosures are designed to drain.
Click to expand...

I'm talking about the use of fittings with straight threads in the threaded openings of Bell boxes and, in this case, the threaded hub on top of a meter pan. Technically not allowed but we have no choice given the products that the manufacturers provide.

K8MHZ said:
We don't seal the weather heads, so what would be the point of sealing threads on the mast?
Click to expand...

Weather heads do actually provide a good degree of water rejection when installed properly- above the point of attachment and drip loops.

We are required here when using SE to seal around the cable with dux seal where it enters the WP compression connector on top of the meter. (A compression connector technically not allowed to be used with a threaded hub. :eek:hmy:)

-Hal
 
Dansos said:
We do not do a lot of service masts in our area (mostly PVC and POCO connects to structure). When installing the rigid pipe into the meter hub, does that section of thread need a special sealant? NEC is pretty vague. Is this up to POCO?
Click to expand...

I've never seen / heard of a thread sealant requirement for masts that comes from any power company regulation.

The mast is a raceway that is directly exposed to weather, therefore, per Article 100 definition, the interior of the mast is defined as a "wet location". Sealing the threads won't change that. The water has to be given ways to drain, as part of the installation of the raceway.
 
I always use plumbers pipe dope on the PVC male adapter to the meter hub and even on the wet connector when using SEU.
When I was a first year journeyman, first solo electrical service, the tip of the clapboard was lined up perfectly with the top of the hub (pre-pipe dope). It leaked on me once..only once;)
 
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