Installation instructions are considered to be a part of the UL Listing.

[don_resqcapt19]

Unfortunately, rigid couplings (as made up standard without thread sealants or conductive pipe dope) are not technically watertight (as in a standard plumbing application - matching tapered fitting and pipe thread). The primary reason is that the straight thread couplings do not have matching tapered conduit threads. Standard, three piece unions also do very little in keeping rain out due to non-gasketed junctions. This probably constitutes a majority of the water intrusion locations within a run of rigid conduit. The standard straight coupling could be made with tapered threads, but it would certainly increase the cost - which many won't pay for. We already have a solution for a RT 3-pc coupling which we offer.

On the other hand, conduit bodies and entrance hubs have tapered threads, gaskets, and are listed as raintight. So are some compression fittings.

Perhaps one day, there will be a Raintight requirement for these types of standard threaded rigid fittings when used outside.

Actually about 30 years ago the Canadian Electrical Code required the use of tapered thread conduit couplings, but under pressure from the major conduit manufacturer's their code was changed to permit the use of the much cheaper to manufacture straight thread couplings. One of the complaints that the conduit manufacturers received after that change was that the conduit now leaked water.

I am sure that the 3 piece raintight coupling would be much more expensive than a tapered thread coupling as well as the additional labor costs that are required to install a 3 piece coupling over that required to install a standard type coupling.

Neither the code nor the listings require that the rigid couplings be water tight and therefore we need to provide some method of draining the water. Yes, there are drain fittings made for the purpose, but often in industrial applications, there is no room to install the tee fitting that is required to use them so a common practice is to drill a small hole in a conduit body or notch the conduit body gasket.

As far as the conduit bodies and threaded enclosures having tapered threads, that may be part of the problem. If these threads were straight threads, maybe the water could drain out on its own.

This whole issue of the newer UL standard that requires the use of watertight EMT connectors and couplings in wet locations has always puzzled me in light of the fact that a rigid coupling is not watertight and are permitted to be installed in wet locations.

 

[don_resqcapt19]

...
Pitching the conduit to allow it to drain into enclosures with installed drains is the solution, but the question was do you drill the enclosure and just leave the open hole without putting a one way drain device? Maybe one of those Gore-Tex patches (lets water pass one way but not in reverse) over the drain hole is the answer?

I have never seen an issue caused by the small drain hole but have seen a lot of damage caused by water filled conduits especially here where it often gets below freezing. When the water in the raceway is frozen there is extreme pressure placed on the conductor insulation and that often results in damage. On a couple of occasions I have seen the conduit split and a #12 of 14 conductor pushed out of the split causing a short when the ice melted. I have worked on the repair of many more damaged conductor where the insulation was crushed to point of failure by the ice.

 

[LJSMITH1]

Actually about 30 years ago the Canadian Electrical Code required the use of tapered thread conduit couplings, but under pressure from the major conduit manufacturer's their code was changed to permit the use of the much cheaper to manufacture straight thread couplings. One of the complaints that the conduit manufacturers received after that change was that the conduit now leaked water.

I am sure that the 3 piece raintight coupling would be much more expensive than a tapered thread coupling as well as the additional labor costs that are required to install a 3 piece coupling over that required to install a standard type coupling.

Neither the code nor the listings require that the rigid couplings be water tight and therefore we need to provide some method of draining the water. Yes, there are drain fittings made for the purpose, but often in industrial applications, there is no room to install the tee fitting that is required to use them so a common practice is to drill a small hole in a conduit body or notch the conduit body gasket.

As far as the conduit bodies and threaded enclosures having tapered threads, that may be part of the problem. If these threads were straight threads, maybe the water could drain out on its own.

This whole issue of the newer UL standard that requires the use of watertight EMT connectors and couplings in wet locations has always puzzled me in light of the fact that a rigid coupling is not watertight and are permitted to be installed in wet locations.

It puzzles me as well and I work for a fittings manufacturer...:roll: It's one thing if condensation is all you would need to deal with, but rain water should be easier...:roll: I would be more than happy to manufacture a tapered thread coupling listed for wet locations if people would pay the $$ for it.

If you recall, back in 2001 or 2002, all compression fitting manufacturers were de-listed (including my company) because their fittings were not raintight when installed in the field. I always wondered why they didn't go all the way and de-list rigid couplings and 3 pc couplings for the same thing.

 

[LJSMITH1]

I have never seen an issue caused by the small drain hole but have seen a lot of damage caused by water filled conduits especially here where it often gets below freezing. When the water in the raceway is frozen there is extreme pressure placed on the conductor insulation and that often results in damage. On a couple of occasions I have seen the conduit split and a #12 of 14 conductor pushed out of the split causing a short when the ice melted. I have worked on the repair of many more damaged conductor where the insulation was crushed to point of failure by the ice.

If the water has no place to go when it is freezing, it will certainly do a lot of damage. I just wonder if you could seal a raceway well enough to limit (not eliminate) air movement, and to completely prevent water intrusion. Is that practical or desired in the field?

 

[LJSMITH1]

Well typical project typical duct bank

With all due respect your wrong pvc will leak it doesnt matter what method you use electrical conduit is not pressure rated like plumbing .

Its not made to seal sorry but i will be more than happy to have you come out and see for yourself .

We use your standard pvc glue and we pour it on 4 inch and 6 inch thats done because its not going in all the way unless you put lots of glue on .

Now the molded ends are not perfect from factory you may think they are tight but there not water tight now if a electrician was to use plumbers weld glue the gray stuff it would seal better but we use your standard electrical supply pvc glue and cleaner .

Its installed dry and we use a 5 lbs sledge hammer to pound them together each pipe is hit until it bottoms out you mark each pipe with a magic marker so we know its in all the way in coupling you cant pull it apart but it will leak .

Before we pull wire we blow out conduits with a 120 LB compressor clean it swab it run a mandrel down it and measure it after we pull wire when the head comes up its water city .

Pvc conduit leaks the main issue is its not molded perfect and they make pvc couplings short there not long enough and there not tight enough .

When we order conduit we ask for long bells this is a better seal but its still leaks i can not explain this any better .

We dont cut corners its done and we dont spare the glue .

So, if I understand you correctly, you only swab one end of the conduit with the solvent glue before connecting the two ends together? Or do you not use any glue and connect them dry?

Maybe the leaks are prone to the bell-ended style conduit connections rather than separate connector/coupling fitting connections? While I have not personally utilized PVC bell couplings bigger than 2", I have always felt there was a suitable, water-resistant seal due to its tight fit. Mechanically, there should be little difference between a plumbing solvent weld and a conduit solvent weld. Maybe at the larger size of 4"-6" there is a less consistent sizing of the bell ends. In that case, no matter how much solvent was used, there would always be a sealing problem.

I have always put the cleaner and glue on both ends of the connection and slightly twisted the two together as I was pushing them. Sometimes the twist is not possible, and you can only push. One thing is for certain, the solvent must be used on both parts of the connection to soften both surfaces before they are mated.

BTW, I know electrical PVC is not pressure rated, because it doesn't have to be.

FYI...Here is an excerpt from IPEX regarding the installation of their PVC conduit..

http://www.ipexamerica.com/Content/Common/downloadPDF.asp?ID={A3B0E033-111B-4133-9BA1-465AC95C9CB1}:

After cutting Scepter Rigid PVC Conduit:

1. Remove all sharp edges or burrs from the inside of the conduit with a knife.

2. Thoroughly clean the end of the pipe and inside the fitting with a rag or
pipe cleaner.

3. Check the pipe and fitting for a dry fit before cementing.

4. Apply a generous amount of IPEX solvent cement to both surfaces; slide
together and give a quarter turn to ensure the solvent is spread evenly on
the material.

5. Hold together for a few seconds until the joint is made.
Usually the solvent-cemented joint will be strong enough to install immediately.

However, in climates with low temperatures or areas with high humidity, extra
time may be required before moving the pipe for permanent installation. Solvent-cemented joints appear to ?set up? instantly, but will take up to 24 hours to cure properly. After this time, the solvent-cemented joint has completely cured and is waterproof. For extreme cold weather installations, the use of IPEX PVC Primer is recommended. Normal installation temperatures are between 40?F and 110?F, however, high strength joints have been made at temperatures as low as -15?F with quality cements. In these extreme conditions the cement must be kept warm to prevent excessive thickening and gelation in cold weather. IPEX cements and primers are available in half pint, pint, quart and gallon containers. The shelf life of conduit cement and primer is 2 years from the date of manufacture. The date code stamped on the bottom of the can is the date of manufacture, not the expiry date. Always verify that the cement is within this 2 year time frame before using.

 

[S'mise]

Rmc

Rmc

Yes, tapered couplings would be better.

Water leaking into conduit is quite pervasive, but a good seal can be made with straight thread couplings and NPT conduit sticks.
If a good pipe dope or conductive compound is used and threads have the proper taper, it should seal just fine provided it's wrench tight.

Also, I see on jobs with long runs of pipe where the couplings get flexed from moving the pipe around. That causes leaks too.

 

[ohmhead]

So, if I understand you correctly, you only swab one end of the conduit with the solvent glue before connecting the two ends together? Or do you not use any glue and connect them dry?

Maybe the leaks are prone to the bell-ended style conduit connections rather than separate connector/coupling fitting connections? While I have not personally utilized PVC bell couplings bigger than 2", I have always felt there was a suitable, water-resistant seal due to its tight fit. Mechanically, there should be little difference between a plumbing solvent weld and a conduit solvent weld. Maybe at the larger size of 4"-6" there is a less consistent sizing of the bell ends. In that case, no matter how much solvent was used, there would always be a sealing problem.

I have always put the cleaner and glue on both ends of the connection and slightly twisted the two together as I was pushing them. Sometimes the twist is not possible, and you can only push. One thing is for certain, the solvent must be used on both parts of the connection to soften both surfaces before they are mated.

BTW, I know electrical PVC is not pressure rated, because it doesn't have to be.

FYI...Here is an excerpt from IPEX regarding the installation of their PVC conduit..

http://www.ipexamerica.com/Content/Common/downloadPDF.asp?ID={A3B0E033-111B-4133-9BA1-465AC95C9CB1}:

Well when a electrician says SWOB it doesnt mean glue thats when you pull a brush thur or a heavy cloth sock made to clean or clear excess pvc cuttings and it cleans the inner walls of the conduit at the same time it wipes or smooths out the pvc glue thats still spider webbed inside each coupling which never drys for months .

The process of connecting large conduit into a coupling meaning a bell first you are not going to ever twist or turn 2 1/2" thur 6 "inch conduit not in this life time . You bang them together!

You use a sledge hammer and two men one holds the conduits together and glues both the coupling with lots of glue and the pipe end with lots of glue we go thur hundreds of gallons of glue on each project .


Bottom line is you really need to come out to a job site during a duct bank party and ill show you how conduit is run in the real world ,

Its hard work a crew of 20 men and lots of glue !


We dont need to read how to run conduit but thanks for the web page i work for one of the 23 rd largest electrical contractors in the USA and we work here and in other countrys so we know how to glue conduit .

Take care

 

[ohmhead]

Well heres the problem with electrical conduit its manufactured different than plumbing pipe look inside the coupling thats your main problem its not a square tight fit its made to allow conductors to not hit a ridge when passing thur bell to straight end its physically not made to seal it expands per manufacture .

Its made to expand read the facts from any conduit manufacture and they will say its not for plumbing use because it will not seal under pressure .

The electrical pvc glue made today is what it is its not a good weld bottom line is most glues are not going to seal large conduit unless we use plumbing gray welding glue .


So points in error here its the glue its the pipe and its the location were its done but as far as those instructions you posted iam trying not to laugh no one is going to wait on a high production project or handle conduit like dont move it let it dry were talking labor hours most projects the cost of glue we use would be a small commercial bid sorry but thats a fact.


What you guys need to manufacture is better glue that is slow dry time but seals better thats not my problem its who ever makes GLUE we cant wait to see that day .

Make a coupling longer make o ring seal internal in conduit and hire a electrician to design it
It would be labor saved

Take care and use lots of glue

 

[jmellc]

Sometimes common sense must rule. I've chucked supplied connectors too. I use them if they are good, but junky ones go in the trash. I won't screw up my work for sake of instructions. I'll be held liable if the junky connector causes a problem.

 

[LJSMITH1]

Well when a electrician says SWOB it doesnt mean glue thats when you pull a brush thur or a heavy cloth sock made to clean or clear excess pvc cuttings and it cleans the inner walls of the conduit at the same time it wipes or smooths out the pvc glue thats still spider webbed inside each coupling which never drys for months .

The process of connecting large conduit into a coupling meaning a bell first you are not going to ever twist or turn 2 1/2" thur 6 "inch conduit not in this life time . You bang them together!

You use a sledge hammer and two men one holds the conduits together and glues both the coupling with lots of glue and the pipe end with lots of glue we go thur hundreds of gallons of glue on each project .


Bottom line is you really need to come out to a job site during a duct bank party and ill show you how conduit is run in the real world ,

Its hard work a crew of 20 men and lots of glue !


We dont need to read how to run conduit but thanks for the web page i work for one of the 23 rd largest electrical contractors in the USA and we work here and in other countrys so we know how to glue conduit .

Take care

I wouldn't expect that someone would twist a 6" or even a 4" duct while assembling. :roll: While my company does not make conduit, glue, or even PVC fittings, I find it interesting that there is a problem with getting these things together.

Isn't there a pipe assembly 'tool' that will 'pull' the two pieces of pipe together? I have seen them used to assemble gasketed SCH80 PVC drain pipe. Without that tool, you would find it very difficult to pound both pipes together and compress the seal.

I understand you know what you are doing, so no disrespect. I am just asking questions.

 

[iwire]

Isn't there a pipe assembly 'tool' that will 'pull' the two pieces of pipe together?

Not that I have seen, and in a closely spaced duct bank that could be tough.

Then there is speed, don't just blame the ECs for that, the customers always want the job done for less.

IMO we have to keep in mind that we are not required by code, spec or even good practice to keep the inside of conduits dry that are installed in wet locations. That is why we are required to use type W conductors.

 

[ron]

we are not required by code, spec or even good practice to keep the inside of conduits dry that are installed in wet locations.

That would be pretty funny to try and enforce that if it were so.

I'll stick to requiring donuts every Thursday when I show up. That's easier to enforce.

 

[don_resqcapt19]

If the water has no place to go when it is freezing, it will certainly do a lot of damage. I just wonder if you could seal a raceway well enough to limit (not eliminate) air movement, and to completely prevent water intrusion. Is that practical or desired in the field?

I can't imagine that it is really possible to seal the conduit system that tight, short of pressurizing it with dry air or nitrogen. I think over time any conduit system, even one with tapered thread couplings, in an area that is exposed to changing temperatures will end up filled with water.

 

[don_resqcapt19]

...I always wondered why they didn't go all the way and de-list rigid couplings and 3 pc couplings for the same thing.

I still think that the de-listing of the older EMT couplings was a scam of some sort. The older compression type EMT couplings leaked less in wet locations than the straight thread rigid coupling.

Given the history of manufactures changing rules in codes and standards to increase their bottom line, I don't understand why they didn't push for the same rules to apply to both rigid and EMT and require the use of a more expensive tapered thread coupling. A quick check this morning shows I can buy a 3/4 rigid conduit coupling for 75 cents and a 3/4 zinc plated tapered thread plumbing coupling for $2.25.
Looks like they missed a chance to increase profits by the use of the code or standards, even though this change, like many other manufacturer initiated changes, would really do nothing to increase the safety of the sytem

 

[don_resqcapt19]

I wouldn't expect that someone would twist a 6" or even a 4" duct while assembling. ...

This is a perfect example of an manufacturer's instruction, that you say must be followed, that really can't be followed in many cases. As Ohm said it is virtually impossible to turn the larger sized conduit as it is being installed, but the instructions call for the installer to make a 1/4 of the pipe as they slide the two pieces together.

Cementing PVC Conduit:
1. Make square saw cut with fine tooth saw.
2. Deburr and round inside edge of the cut end.
3. Clean socket ID and spigot OD of dirt and moisture.
4. Apply a uniform coat of cement to spigot end and
push onto socket bottom, rotating 1/4 turn.
5. Allow time to set before disturbing. This will depend
upon temperature

 

[ohmhead]

Well reading that instruction Don i see another problem we kinda put glue on pvc pipe end and we put glue inside of that pvc coupling or bell end of other pipe but that instruction you just posted states end of conduit only ? and twist? that will not work on 4 " or 5 " or 6 " We do wipe out our conduits before we apply glue just in the morning before the sun comes up we use a rag .

About the tool to put conduit together it would be easy to make one but not of any use with multiple layers after you reach the top of the bank how would you get to the bottom row ?

It would be kinda a two fork looking thing with a short or long fork hand level pull device but its really not that difficult to just bang them together you seem to think we beat the hell out of the pipe. Electrical conduit is tappered on outside it will not work very good labor lost but nice thought .

Nop one or two taps like puttin a golf ball easy just slides up but if you push it by hand you will be dead after 8 hours of installing pipe all day.

 

[LJSMITH1]

I still think that the de-listing of the older EMT couplings was a scam of some sort. The older compression type EMT couplings leaked less in wet locations than the straight thread rigid coupling.

Given the history of manufactures changing rules in codes and standards to increase their bottom line, I don't understand why they didn't push for the same rules to apply to both rigid and EMT and require the use of a more expensive tapered thread coupling. A quick check this morning shows I can buy a 3/4 rigid conduit coupling for 75 cents and a 3/4 zinc plated tapered thread plumbing coupling for $2.25.
Looks like they missed a chance to increase profits by the use of the code or standards, even though this change, like many other manufacturer initiated changes, would really do nothing to increase the safety of the sytem

If that was a scam, we certainly didn't hear about it. All I know is we had to scramble to redesign our RT compression fittings to meet the 'revised' UL514B requirement. Even though we were first on the market with a new & patented design, there were others that came soon after. I still don't know who tipped-off UL that there was an issue with ALL manufacturer's RT compression fittings (and probably never will find out..:-?).

As for the tapered thread coupling, we probably could do better than the plumbing version, but it will certainly be more than the standard coupling (mabye $1.50?). Plus we would need to fight the conduit manufacturer's as they currently supply the straight thread couplings with the lengths. UL would need to change the UL514B specification to specify that these types of rigid fittings need to have tapered threads if they are to be RT.

BTW...The manufacturers are not the only ones that are members of the particular committees that are involved with UL specification changes. There are folks from the NFPA, NEMA, ANSI, CSA, AHJ's and others which all vote on the proposed changes. The proposals can come from any member of the committee. In addition, the specifications need to harmonize with the NEC. I am not a conspiracy theorist, and I know that specification changes (at least in the fittings world) are done with a consensus.

 

[LJSMITH1]

This is a perfect example of an manufacturer's instruction, that you say must be followed, that really can't be followed in many cases. As Ohm said it is virtually impossible to turn the larger sized conduit as it is being installed, but the instructions call for the installer to make a 1/4 of the pipe as they slide the two pieces together.

Nothing is impossible! :grin:

What about using a large strap wrench to turn the pipe as it is pushed? It might even help fit them together tighter.

Here is the assembly tool I was referring to earlier. I wonder if it would work on the larger conduit?
http://www.propipesolutions.com/index.html

I can't believe nobody has come up with a compact, one or two man tool that eliminates beating the end of the conduit with a 5lb sledge...

 

[ohmhead]

Well you really need to work in the field to know what your suggesting you cant use it on duct banks and thats not electrical conduit thats sewer pipe which we see everyday installed by the plumbing & mechcanical contractors which they never use because its a joke .

Yes weve seen that tool no one ever uses it . plus on 24 " it would need to be used with a crane to move it around .

They use a track hoe and two men to push that kinda pipe together its easyer ill get a picture of a install at work today for you have you ever seen 18 " or 24 " sewer pipe installed its heavy held up by a track hoe with a strap then two men line it up and the track hoe pushes the pipe together easy .

Plus they apply a grease to the seal before they connect it then it slides in

We dont beat a conduit like i said we tap it in with the side of a sledge hammer like puttin a golf ball its kinda easy . We tap it together like one or two feather taps.

 

[don_resqcapt19]

Yes, tapered couplings would be better.

Water leaking into conduit is quite pervasive, but a good seal can be made with straight thread couplings and NPT conduit sticks.
If a good pipe dope or conductive compound is used and threads have the proper taper, it should seal just fine provided it's wrench tight.

Also, I see on jobs with long runs of pipe where the couplings get flexed from moving the pipe around. That causes leaks too.

I am not aware of any pipe dope or compound that will seal that joint that is also listed for use with conduit.