Practical differences between plumbing PVC and conduit?

[00RT]

Hi all, I’ve seen differing info on this topic when I searched the web, so I thought I’d see what folks here have to say.

I’m wondering what physical/practical differences there are between white plumbing PVC and gray PVC electrical conduit.

Here’s why I’m asking. My detached garage/shop currently has the power run to it via 4-4-4-6 Type SE aluminum cable in 1.5” white sch40 PVC. I bought it this way and have been holding off on doing anything until I started fixing up the garage since I had power off at the main panel anyway.

I want to replace it with 2-2-2-4 Aluminum MHF in 2” conduit. The problem is that it runs under my patio. What I’m thinking about doing is digging up the existing up to the edges of the patio, cutting the pipe that’s there, and rebuilding outward from there with 2” conduit. The pipe under the patio is straight, so I should be able to pull that size cable through it even though it’s only 1.5”.

Yes, I realize this isn’t to code. And while I’m trying to do everything I can by-the-book, I’m really having trouble justifying tearing up the patio for something like this that seems more “the letter of the law” than the “spirit of the law”. I think technically if it was 24” deep it might be legal since the cable is rated for direct bury, but it’s barely the 18”. The pipe is sch40, it’s under a patio. In the real world, is it going to be any less safe than conduit?


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[rlitman]

...I think technically if it was 24” deep it might be legal since the cable is rated for direct bury, but it’s barely the 18”. The pipe is sch40, it’s under a patio...

The 24" requirement is under open ground. It doesn't need to be that deep under a slab.

 

[Norcal]

I cringe when I hear about, or see white PVC pipe being used as conduit underground, someone could think it is waterline and cut into it not knowing there are cables inside that did happen to me many years ago and was thankful it was not live. With gray conduit it should be electrical, although have seen conduit being used as waterline too, but the gray color does warn it should be electrical.

 

[rlitman]

I cringe when I hear about, or see white PVC pipe being used as conduit underground, someone could think it is waterline and cut into it not knowing there are cables inside that did happen to me many years ago and was thankful it was not live. With gray conduit it should be electrical, although have seen conduit being used as waterline too, but the gray color does warn it should be electrical.

Fair enough.

Here's a wild thought. Use the existing conduit path to help horizontally bore in a new conduit in it's place.

 

[Bert_]

In many areas the depth is a dead give away it's not water. I've seen electrical conduit so light grey I thought it was plumbing pipe before I read the side of it.

I may have used a white coupling or a short piece of pipe once or twice before when I ran short on parts. No hardware store carries electrical PVC bigger than 2" and the electrical supply is 45 minutes away.

If you pull wire rated for direct burial then there's really nothing they can ding you on. Do make sure that the 90s or other bends are electrical 90s/ect and replace them if necessary.

 

[Innovate1]

I wouldn't change size in the middle of the run. You aren't supposed to glue the pipe with wire installed. You are supposed to put the pipe together and then pull the wire. A step change in size will cause you grief with possible hang up unless you pull in the other direction. If it was me I would just replace the existing that you can get to (not under the slab) with electrical conduit and call it good. Use a sweep at the riser. Bend a bigger radius one - it will make the pull easier, especially if the fit is a bit close. If you only have two bends the standard radius will work with a bit more effort.

2-2-2-4 will go through 1.5" fine. I would use single strands of XHHW though. No twists to hang up anywhere. But I think you should be ok with MHF - probably should see what a few others say. I don't have experience pulling MHF. XHHW was recommended to me so I used that.

 

[nadogail]

IMHO, if your inspector sees the white PVC, it's all over because White PVC is Not Approved For The Purpose.

 

[Norcal]

In many areas the depth is a dead give away it's not water. I've seen electrical conduit so light grey I thought it was plumbing pipe before I read the side of it.

I may have used a white coupling or a short piece of pipe once or twice before when I ran short on parts. No hardware store carries electrical PVC bigger than 2" and the electrical supply is 45 minutes away.

If you pull wire rated for direct burial then there's really nothing they can ding you on. Do make sure that the 90s or other bends are electrical 90s/ect and replace them if necessary.

I would not fault someone for using a white coupling in a run, it is not listed for the purpose but sometimes you gotta do what you gotta do in a pinch. But since most DWV pipe is ABS here, a hardware store is not going to have anything over 2” in PVC anyway.

 

[vhol5]

What about a handhole (Small concrete junction box) at the end of the patio for the transition?

 

[Bert_]

IMHO, if your inspector sees the white PVC, it's all over because White PVC is Not Approved For The Purpose.

I know of a large contractor in my area that did a bunch of underground with Smurf tube and then pulled direct bury wire. Inspector had a fit but got overruled since the wire was not required to be in anything at all.

 

[u2slow]

What about a handhole (Small concrete junction box) at the end of the patio for the transition?

Seems reasonable, but if being inspected, may get called on the enclosure requiring an electrical rating.

I know of a large contractor in my area that did a bunch of underground with Smurf tube and then pulled direct bury wire. Inspector had a fit but got overruled since the wire was not required to be in anything at all.

That fails here due to 'insulation stacking'. Same as running NM cable in conduit inside or above ground. IMHO, its a fairly weak argument... sometimes it feels like the AHJ also can't have gravy touching their peas.

 

[00RT]

Thanks for all the comments so far.

Regarding getting it inspected, that’s something that I’m currently struggling with. Typically I will pull a permit and do things by the book. The issue I’m having here is that based on what I’m seeing, there was a lot of work done previously without an inspection. Unfortunately, I can’t make it code compliant all at once. I want to focus on fixing the things that are legitimately unsafe, but I’m afraid pulling a permit to do so is going to call everything else into question. The other side of that, aside from violating the law, is furthering the history of un-permitted work instead of stopping it and making it right. So, I find myself with a conundrum.


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[vhol5]

In my experience, inspectors look at what's on the permit, and nothing else, unless a glaringly dangerous situation is noticed. At least it's that way in my area.

 

[u2slow]

Regarding getting it inspected, that’s something that I’m currently struggling with. Typically I will pull a permit and do things by the book. The issue I’m having here is that based on what I’m seeing, there was a lot of work done previously without an inspection. Unfortunately, I can’t make it code compliant all at once. I want to focus on fixing the things that are legitimately unsafe, but I’m afraid pulling a permit to do so is going to call everything else into question. The other side of that, aside from violating the law, is furthering the history of un-permitted work instead of stopping it and making it right. So, I find myself with a conundrum.

Due to how my building inspector handled himself nearing the end of my shop build, those authorities are no longer welcome at my premises.

I did my electrical apprenticeship under one Code. Now I work under another. Plus all this great NEC exposure online (3rd Code for me). Codes are inconsistent, and some change every few years. OTOH, the science/physics is universal - and that's what matters most to me.

Whatever DIY project I have going on, I maintain a level of workmanship that lets me sleep at night, and affords reasonable safety for me and my household.

 

[00RT]

Due to how my building inspector handled himself nearing the end of my shop build, those authorities are no longer welcome at my premises.



I did my electrical apprenticeship under one Code. Now I work under another. Plus all this great NEC exposure online (3rd Code for me). Codes are inconsistent, and some change every few years. OTOH, the science/physics is universal - and that's what matters most to me.



Whatever DIY project I have going on, I maintain a level of workmanship that lets me sleep at night, and affords reasonable safety for me and my household.

I hear ya, man. That’s a big part of my issue. I’m new to this town. The people in general are great, but I’ve met a few on power trips. The inspector could be a cool and reasonable guy I can work with, or he may be one of those impossible to please types. And I’m not sure I want to gamble with that. Safety is my number one concern. I may not be well versed in all the nuances of the code, but I have a BSEE and a solid understanding of electricity. My dad also spent most of his career working for a wire and cable company. Initially as a field tech traveling around and splicing huge underground feeders in manholes, and then in the quality lab. So, I always run anything electrical by him.

The can of worms I’m afraid to open is that currently there is Type SE cable running through my basement garage on top of the drywall and then out to the detached garage. In addition to the SE, there is NM that’s been added for various things over the years. Some of it runs along with and is bundled to the SE. Because the ceiling needs to be drywall for fire protection, you can’t run wire along the joists like you typically would in a basement (the original was done that way, but not stuff that’s been added). None of that wiring is to code being exposed like that. It will all be done properly and run through conduit at some point, but it’s going to take some time for me to do that project. Right now my plan was to transition from the new 2awg aluminum XHHW-2 or MHF feed to the existing 4awg SE in the basement garage in a junction box and leave the 50A fuse. Then when I do all the conduit in there, I’ll replace the SE with 4awg copper since it isn’t a long run and I want to minimize size and then switch to a 90A breaker to utilize the 2awg feeder.

Now, I think that is a reasonable approach and not unsafe (other than the unprotected SE and NM, but that’s like that now anyway). But, i don’t think it will fly with the inspector. He’s not going to want power running to the detached garage at all until the conduit is all done in the basement. And that bugs me, because this house has been like this for a long time and everything I’m doing, even though it’s in steps, is making it safer.


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[nadogail]

IMHO, if you find that the inspector is being unreasonable and you are absolutely certain, with out a doubt you are correct you might consider calling the office that Isses the permits and request another inspector.

This approach should be considered very carefully, a cooperative relationship with your inspector can make a job go better.

 

[AntonLargiader]

But, i don’t think it will fly with the inspector. He’s not going to want power running to the detached garage at all until the conduit is all done in the basement. And that bugs me, because this house has been like this for a long time

Well, the thing is that you are modifying a circuit and therefore the whole circuit needs to be brought up to date. But around here, there doesn't seem to be a super critical timeline. If you want to be sure you're under permit for some work, you get a permit and then basically it is in effect as long as you don't go six months without working on it. So maybe you could fix that first part under permit, but not call for an inspection until the second part is fixed even if it's a year from now.

Why not give him a call and see what the timeline is for inspections? Make sure he realizes there is pre-existing power to that outbuilding.

 

[00RT]

Well, the thing is that you are modifying a circuit and therefore the whole circuit needs to be brought up to date. But around here, there doesn't seem to be a super critical timeline. If you want to be sure you're under permit for some work, you get a permit and then basically it is in effect as long as you don't go six months without working on it. So maybe you could fix that first part under permit, but not call for an inspection until the second part is fixed even if it's a year from now.

Why not give him a call and see what the timeline is for inspections? Make sure he realizes there is pre-existing power to that outbuilding.

Standard permits are 180 days max unless you request an extension in writing with a justifiable reason for why the work hasn’t commenced. If the permit is to repair something that is “unsafe” rather than new work, the inspector can issue it for no more than 180 days but as short as 30 if they choose to.

It ***** because they want you to do the right thing, but sometimes by opening the door you can be setup for a real headache if the inspector decides to be a hardass.