Counterman at the supply house asked me if I glued PVC conduit when installing it under- ground. My answer was yes, to which he said two electrical contractors had just told him that you do not glue PVC conduit when installing it underground. Have I always just done it wrong or what?

Keep on gluing. 2002 352.48

"all joints shall be made by approved method"

I would doubt that no glue is an approved method

We glue our PVC. I would never think of not glueing. However, any conduit installed underground is going to get a lot of water inside, glued or not, due to condensation. This is why the NEC defines underground conduit as a wet location.

the glue will help keep the water out of the conduit too....

I think that those two contractors must of done a bit of glue sniffing in their day!LOL

The best part about gluing is that you have some hope of getting the water out.

Think about this; what if not glueing allows the condensation to drain out?

I know of a guy that didn't glue the pipes in a duct bank that got concrete encased. They don't stay together very well in that scenario!

You "glue guys" probably cut threads in rigid too -- I just put them sticks together with rubber Fernco's...

Len

This will sound strange to you guys I know.Our outfit does plumbing also,we alwaysduct tape a can of cleaner/primer to a can of glue for running pvc drains/waterlines.I know there will be giggles about this, but I,out of habit use the cleaner for pvc conduit also.

RobbieD,
If there is one thing that I cannot stand, it's the smell of PVC Conduit solvent, it's even worse, if you've got a hangover.
Dunno how the glue-sniffers do it!.

Cleaner/primer might not be listed for use with R.Nonmetallic conduit. I know one thing though, i use more glue lately, cause the bell ends are longer.

What kind of PVC glue do you use?

We usually use this thick gray colored glue, but recently I saw my guys using some regular clear PVC cement and I asked where they got it, because I thought this wasn't right for the soft electrical pvc. They said the supply house gave it to them, so I guess it doesn't matter????

I'd like to learn if there is any technical difference between "electrical (listed) glue" and "plumbing" PVC cement.
Personally, I prefer the grey plumbing glue to the clear electrical glue, because I have more working time, and it matches the pipe color (better than the red/blue/whatever glues). Also, the plumbing glue is available in smaller containers- I don't often do enough PVC to warrant keeping a quart on the truck!

We do glue our direct burial PVC pipes, but we and the Hydro people, do NOT glue the Type II (DBII aka thin wall rigid conduit).

We've used a pvc glue made I believe by carlon.It says on the can it's "especially formulated" for rnc.It also states" not for use for presserized lines".Usually for rnc we use the "rain or shine" glue made by Oatey.It.s a thick bodied glue,blue in color. If it's an exposed job we use the clear.

We don't glue our DB II either only our rigid PVC, maybe Sandro and I are doing something wrong? Just thought thats what everybody did.

Why would it make any difference what thickness the pipe is? I can understand how it's important that the conduit stays connected together, therefore necessitating glue. But, the way some larger runs of pvc go together, I doubt that it could come apart due to ground movement, or backfilling, or concrete pours (assuming it is staked down).

More to the point though, it would seem possible that clay (as well as concrete slurry) could seep into the conduit along with the ground water, and make it hard or impossible to pull the wire out later. Maybe this is why you have to glue it together?

Glue, NAW! We use Scotch Tape. Just kidding. Has anyone had any problem with the ground heaving? Due to frost? Here in NJ I have seen pipes pull apart and the ground move up and down by an inch or so due to the frost. I have seen PVC pipe pull right out of a box because of the frost. I might even get a picture on the board. ( I just need my kid to help with the digital camera. )

Harold.....

A bigger problem I have run into is in new construction, after fresh excavation and then backfill, I have seen many, many cases where the PVC from the meterbase downward into the earth pops out of the meter base because the ground settles (many times after a rainfall) and something has to give!

Many a true word spoken in jest!

I have actually seen surface run PVC conduit patched up with "Sellotape" -- the British brand name equivalent of Scotch tape.

I always glue everything.
PVC cement for conduit we get comes in light (clear, fast dry),medium (gray, medium dry), or heavy (gray, slow drying) bodied.(viscosity).
The heavy is nice for large conduit. It works like a lube, giving you a chance to "adjust things", rather than sieze up like the clear stuff does 1/2 way into the socket.

For those that do not use glue I was wondering if you have to get inspection before backfill, where I am we need approval before backfill and I would think that if it was noticed that there was no glue I would be in for a long "talking to" and be back in the hole with some glue.(:

I know that where I am we don't need to call the inspector for trench work before we backfill.

Also, we use jumping jack tampers after about every six inches of backfill along the whole of the trench or excavation depending on what the job calls for.

We always use glue, and yes, if you don't you will spend a while with a can of glue after getting your butt chewed out.

I find that some inspectors are real tough on using expansion joints for the PVC pipe, and others don't really care if the expansion joint is used or not. What do you guys find out in the field?