plumbers pvc verses electrical

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Electrical lengths often have bell ends. Plumbing lengths don't.
Electrical bends have a larger radius than plumbing elbows.
Plumbers do not use conduit bodies. :)
 
I believe the differences are that electrical PVC conduit has a different flammability rating. It has to slow down the propagation of fire in what is called a Vertical Flame Test to get UL listing. Obviously since it is not intended to be used for wiring, white PVC pipe is not UL listed and not tested for that. On the other hand, PVC conduit is not required to undergo ASTM pressure testing like PVC pipe is.

The only crossover is that they do that on factory threaded nipples because they sell them for more and can afford the dual testing, meaning they start with Sched 80 PVC electrical conduit, because the grey material already has the flammability rating, then pressure rate it for plumbing use. That's why the factory threaded nipples are always grey.
 
In the sizes larger than 1?", plumbing pipe is usually cellular core, which means it's not mean for water pressure and is limited to drain/waste/vent. Electrical conduit is solid core.

Take a look at a cut end of both and you'll see the difference. The cut end of white plumbing pipe will look like foam.
 
Plumbing PVC couplings have a taper, which is why when its glued the hydraulic pressure forces the pipe back unless you hold it
Plumbing PVC requires a primer
Plumbing PVC is designed to hold pressure, electrical is not and its not a water proof wiring method

Running electrical wires in plumbing PVC is dangerous, as you don't expect any wires if you cut it.
 
I will not question whether the couplings have a taper, but that is not why pressure forces the joint apart. The pressure multiplied by the cross sectional area of the inside of the pipe is the source of the force pulling the joint apart
 
GoldDigger said:
I will not question whether the couplings have a taper, but that is not why pressure forces the joint apart. The pressure multiplied by the cross sectional area of the inside of the pipe is the source of the force pulling the joint apart
Click to expand...

The pressure is when you are gluing the pipes together, the taper and the glue will push the pipe out unless you hold it for a bit.
This is different from the hydraulic pressure in the pipes. In large water mains, 6", 8", at corners and water meters, there is typically a yard of concrete as a thrust block. We have some 36" dia pipes and those have huge thrust blocks, many yards of concrete
 
tom baker said:
The pressure is when you are gluing the pipes together, the taper and the glue will push the pipe out unless you hold it for a bit.
This is different from the hydraulic pressure in the pipes. In large water mains, 6", 8", at corners and water meters, there is typically a yard of concrete as a thrust block. We have some 36" dia pipes and those have huge thrust blocks, many yards of concrete
Click to expand...

interesting!
 
I have never had a PVC joint try to separate after insertion. The dry fit is supposed to be friction tight. As you push the pipe and fitting together the shear force on the glue and dissolved plastic will try to make the pieces spring back. The half or greater twist you are supposed to make after bottoming will break those "springs" and any spring back will tend to twist the pipe rather than separate the joint.

PS: those thrust blocks also have to withstand the much higher pressure created as water flows through the pipe around the bend and the water hammer forces when a valve gets closed.
The pipe itself should be able to withstand the force from static pressure, although that can get pretty high too.
On of the first times I used an in line compression union I decided to silicone grease the rubber to keep it from leaking. Instead it blew apart when I closed the valve with water running. The instructions did not warn against that. Although I guess I should have realized that "clean" meant exactly that. :)
It made a great expansion joint, but the pipe made a turn so there was nothing to restrain it. :(
 
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480sparky said:
In the sizes larger than 1?", plumbing pipe is usually cellular core, which means it's not mean for water pressure and is limited to drain/waste/vent. Electrical conduit is solid core.

Take a look at a cut end of both and you'll see the difference. The cut end of white plumbing pipe will look like foam.
Click to expand...
Huh?

I just used some 2-1/2" Schedule 40 PVC plumbing pipe, it was rated 300 psi

There is cheaper white plastic pipe that is rated as DWV (Drain Waste Vent) only, not the same thing.
 
GoldDigger said:
Electrical lengths often have bell ends. Plumbing lengths don't.
Electrical bends have a larger radius than plumbing elbows.
Plumbers do not use conduit bodies. :)
Click to expand...
I know of one plumber that primarily uses only 20 foot lengths of sch 40 (never any cellular core either). Those that he uses have bell ends. He also told me by using 20 foot lengths he seems to not have as many short scrap pieces as most do if they buy it in 10 foot lengths.

480sparky said:
In the sizes larger than 1?", plumbing pipe is usually cellular core, which means it's not mean for water pressure and is limited to drain/waste/vent. Electrical conduit is solid core.

Take a look at a cut end of both and you'll see the difference. The cut end of white plumbing pipe will look like foam.
Click to expand...
Pick them both up and there will be noticeable weight difference as well.

GoldDigger said:
I will not question whether the couplings have a taper, but that is not why pressure forces the joint apart. The pressure multiplied by the cross sectional area of the inside of the pipe is the source of the force pulling the joint apart
Click to expand...

This is first I have ever heard of any taper, I don't know if there is or not. Plumbing fittings that need to seal pressure probably have a tighter, more consistent specification for diameter and roundness then electrical PVC pipe and fittings I would assume which itself would probably cause more pressure in the joint when assembling after cement is applied.
 
Years ago I was repairing a sprinkler & there were 3 PVC pipes close together so decided to cut the other two out of the way, big mistake, one of them had a 14/2 UF inside it, not on, or powered up but still gets me riled when I see plumbing PVC pipe used for electrical.
 
norcal said:
Years ago I was repairing a sprinkler & there were 3 PVC pipes close together so decided to cut the other two out of the way, big mistake, one of them had a 14/2 UF inside it, not on, or powered up but still gets me riled when I see plumbing PVC pipe used for electrical.
Click to expand...

Underground - I don't get too excited. Has been very common practice for years - especially on the farms to use a thinwalled PVC pipe as rodent protection for what is otherwise direct burial rated cables, especially in sandy soil areas and around areas where food for rodents would be abundant.

I have gotten away from pulling UF cable through pipe though. It doesn't pull well at all. I'd rather put in proper electrical rated PVC conduit and pull THWN conductors through it. Labor costs to pull the UF plus UF really needs larger pipe then same number and size of conuctors without an outer covering - usually makes up for any differences anyway.
 
another difference I did not see mentioned:

The grey pvc can leach carcinogens into water (at least the formulation used a few decades ago could, may be upgraded by now?) whereas the NSF rated white pvc is verified to not leach carcinogens into chlorinated water.
 
tom baker said:
The pressure is when you are gluing the pipes together, the taper and the glue will push the pipe out unless you hold it for a bit.
This is different from the hydraulic pressure in the pipes. In large water mains, 6", 8", at corners and water meters, there is typically a yard of concrete as a thrust block. We have some 36" dia pipes and those have huge thrust blocks, many yards of concrete
Click to expand...


Tom I have seen this happen with the electrical PVC also. If you don't hold it it will slide back a tad.
 
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