PVC - Cement and Primer

[Ne_EC]

I was reading any posts I could find on this topic - but I'm still confused on the primer. The supply house I typically deal with also does not stock primer - a comment that seemed to echo in a previous post on PVC. How would one know if the primer is compatible with a certain kind of solvent - if they were by a different manufacturer? The primers that I've seen are not the same manufacturer as the supply houses that I buy from.

When using primer, is it just applied like the solvent, simply brushing it on? The primer, I'm assuming is just to help clean the end of the pipe - is that the case?

 

[JES2727]

FYI: I don't use primer on electrical PVC conduit.

 

[iwire]

Any electrical PVC cement I have used had directions that no primer was necessary.

I don't use primer.

 

[roger]

Like the others, I don't use primer or cleaner for electrical PVC

Roger

 

[guschash]

I don't use primer either.

 

[goldstar]

The primer, I'm assuming is just to help clean the end of the pipe - is that the case?

The primer not only cleans the end but also partially softens up the end so that when you apply the cement and put the fitting or bell end on the conduit it will make a more positive connection. As Bob mentioned, most manufacturers suggest that primer is not necessary. I generally don't use it on above ground work but I do use it when burying PVC. My reasoning is that while condensation will, in all probability, form inside the conduit, I don't want to take the chance that water may seep into the conduit due to a fitting that may have come partially ot totally apart. It's just my opinion but I feel more confident that a conduit will stay together better when primed first rather than not.

 

[stickboy1375]

The only time I will use a primer is when installing conduits for inground pool lights, For some reason it just makes me feel better. :smile:

 

[romexking]

I always use primer on electrical conduit. It takes such a short time to apply and it makesthe glued connection much harder to remove. Take this as a example: I'm sure we all have had to remove a coupling or TA from a piece of pvc. With only pvc cement, I can almost always remove the fitting by cutting it with a hacksaw, and then break it away from the conduit with a screwdriver. When we use primer, this becomes nearly impossible. The fitting will shatter into many small pieces that are still stuck to the conduit.

I've never seen plumbing pipe come apart at the fittings after being installed underground for a while, however I have come across many electrical conduits with loose connections at the fittings.

 

[iwire]

Romexking, if the PVC is installed per code, correct supports, expansion fittings etc. why would there be any force applied to the cement joints?

IMO the fact that we do see PVC terminations pulled apart has much more to do with incorrect supports and lack of expansion fittings much more than the fact few people use primer.

 

[mdshunk]

Here's an old thread, where some people gave some reasons why they use primer. That thread also contains a link to a NEMA document on solvent cementing PVC conduit.

http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=11;t=007532;p=2#000015

 

[danickstr]

that old thread is a good reference.

I use the grey glue (med body) and wipe it around the male component enough times to smear the writing off the pipe, and have never seen a failure. I also dab some on the fem end before i start the pipe end.

 

[romexking]

There are times when pvc is installed underground without supports, just laying in the trench. The bottom of the trench is not always completely level, which leaves unsupported conduit susceptible to bending when it is covered with dirt. I would rather be safe than sorry. There is certainly nothing wrong with an installation that is above the minimum requirements. I find that using the primer wastes little time, and makes a better connection.

 

[quogueelectric]

Pvc primer

Pvc primer

In my experience sometimes if you are in an area with known groundwater and runoff problems Primer will seal the pipe to a completely waterproof level.



In a hospital I sometimes work in, the water was intruding into the 4000 amp service pipes and running from the transformer up the hill right into the service equipment and causing havoc.

Putting a coat of primer is a small price to pay in labor to not have a water intrusion problem.

 

[iwire]

Putting a coat of primer is a small price to pay in labor to not have a water intrusion problem.

I leave it off to let the water out.

 

[e57]

Putting a coat of primer is a small price to pay in labor to not have a water intrusion problem.

I agree, and am a firm believer to use primer - I see it as the right thing to do in many situations, as I only use PVC underground where there are water issues, and occassionally in concrete... A little concrete leakage can do a bit of damage...

 

[JohnE]

I almost always use primer on underground installs. I realize it's not necessary, but I do find it makes the pipes "stick" a lot better. I echo what Romexking already posted.

 

[George Stolz]

This is a little off the topic, but today I noticed the glue I was using said "Not recommended for use on Schedule 80 PVC."

Has anybody else noticed this?

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(I mean, I've seen the label, but the can never spoke before... )

Anyway, anybody seen a similar marking on their glue?

 

[roger]

This is a little off the topic, but today I noticed the glue I was using said "Not recommended for use on Schedule 80 PVC."

Has anybody else noticed this?

.
.
.
.
(I mean, I've seen the label, but the can never spoke before... )

Anyway, anybody seen a similar marking on their glue?

And from now on for schedule 80, I will not only not use primer, I won't use glue either. :wink:

Like Bob, I think it's better to let the conduit drain. I have installed T's, drilled holes, and cut slots in underground conduit runs for this very reason.

Roger

 

[quogueelectric]

conduit draining conduit filling

conduit draining conduit filling

Trust me it is not a good feeling to go on a service call and seeing water cascading across a large 480 volt switchgear. It largely depends on the soil conditions and topographical features in your area whether or not water will drain or accumulate and run off into the building. rather than draining into the earth it can be the exact opposite and act as a big funnel into the building especially when a padmount xformer is located in the parking lot in a low corner where all of the water runs directly towards the xformer that is a different building with a different problem tho same results

 

[iwire]

Trust me it is not a good feeling to go on a service call and seeing water cascading across a large 480 volt switchgear.

So water is cascading through cemented but not primed joints?

When water is cascading into the gear through the raceways the issue has nothing to do with lack of primer.

Hey you want to use primer, go for it.

I think my time could be better spent planing the raceway to drain away from the building.