Change from 1" to 1 1/4" conduit in middle of run

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annie09

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I am currently working for a low voltage contractor. There is another electrical contractor on the job who is running our conduit. Due to a problem with the underground PVC conduit they ran, we had the conduit dug up to try to find the problem. The problem we found astounded us. They changed conduit sizes, going from 1" to 1 1/4", by sticking the 1" conduit INSIDE of the 1 1/4" conduit. They have refused to fix this. My question is, what code sections can be quoted that would prohibit this? One would hope that common sense would prevail, but unfortunately, this is not the case. I have looked in the code book, but can't find where it specifically says that you can't change conduit size in the middle of a run. I found a few sections that would apply but they're a bit ambivalent. Thanks for any help.

Annie
 

iwire

Moderator
Staff member
Location
Massachusetts
There is nothing in the NEC that prohibits changing sizes in a run.


About the best you could do is 110.3(B) as it does not sound like they used the parts per the listing.
 

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
They changed conduit sizes, going from 1" to 1 1/4", by sticking the 1" conduit INSIDE of the 1 1/4" conduit.
Annie

How about 300.10 if it is metallic raceway.

300.10 Electrical Continuity of Metal Raceways and Enclosures.
Metal raceways, cable armor, and other metal enclosures for conductors shall be metallically joined together into a continuous electrical conductor and shall be connected to all boxes, fittings, and cabinets so as to provide effective electrical continuity. Unless specifically permitted elsewhere in this Code, raceways and cable assemblies shall be mechanically secured to boxes, fittings, cabinets, and other enclosures.
Exception No. 1: Short sections of raceways used to provide support or protection of cable assemblies from physical damage shall not be required to be made electrically continuous.
Exception No. 2: Equipment enclosures to be isolated, as permitted
 

Volta

Senior Member
Location
Columbus, Ohio
...I do not see that 300.18 prevents changing sizes in the middle of a run steel or PVC.

It doesn't. But 300.18 does require the raceway to be installed "complete" between certain points.

Since "They changed conduit sizes, going from 1" to 1 1/4", by sticking the 1" conduit INSIDE of the 1 1/4" conduit.", no reducing fitting was installed, so that section was not complete.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I am not sure there is anything really wrong with this, depending on just what was done.

Is conduit even required for this application?

If conduit is required and they did not use a reducing fitting, they might need to put a reducing fitting in place, but I can't think of any reason they can't change the conduit size mid run.

I am curious just what problem prompted you to dig up the conduit.
 

Jomaul

Senior Member
Location
Ocala, Fl
I would think that the only code sections that might prevent you from doing this would be the conduit fill and the wire derating sections. other than that plumbers do it all the time.
 

480sparky

Senior Member
Location
Iowegia
I would think that the only code sections that might prevent you from doing this would be the conduit fill and the wire derating sections. other than that plumbers do it all the time.

Raceway size has nothing to do with derating. Plumbers downsize pipes all the time, but usually after they T off.
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
Only violation was not using a reducer. So at best you could demand that. Now we must look at if what your installing even falls under nec. Unless the prints specs say 1 1/4 you get what they care to run. Have seen too many low volt people that simply lack the skill to pull hard runs. Not saying that applies here but just what is the problem ? Does your install require 1 1/4 or is that what you like. I had to run 4 inch pvc for a small school from building to phone pole maybe 70 feet for telephone. Helped the guy pull in his 25 pair line. We often did the pipe work for fire alarm, internet, door openers because there men can't or won't do it. Easy money for us.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
First of all it's for low voltage, my guess either phone or data, neither of which require a conduit.

Now I do think it's wrong the way they did it and using a bell reducer would have saved all kinds of problems. My guess is they reason they dug it up was because they went in from the 1 1/4" side and the tape got hung when it ran into the 1".

I also would have questions about any EC that would install it that way.

If you're going to throw out a code section try 352.48 "All joints between lengths of conduit, and between conduit and couplings, fittings and boxes, shall be made by an approved method."

Sometimes as an inspector we find something that is so out of the norm that there isn't even a code section that you can use. The CMP probably thought that no one would ever do anything like that.
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
He works for a low voltage contractor but dos that mean this conduit is only used for LV? If that is the case then I agree but I was assuming line voltage for some reason.
 

iwire

Moderator
Staff member
Location
Massachusetts
It doesn't. But 300.18 does require the raceway to be installed "complete" between certain points.

Since "They changed conduit sizes, going from 1" to 1 1/4", by sticking the 1" conduit INSIDE of the 1 1/4" conduit.", no reducing fitting was installed, so that section was not complete.

IMO it is complete regardless of the reducing fitting.

Bob you see nothing wrong with this install

As I said in my first post there is 110.3(B) and Cowboys post referencing 352.48 seems to be on the money


Personally I have changed from 3/4" to 1" under a slab when we ran out of 3/4" The bell end of 3/4" fits perfectly into the bell end of 1" and glues up tight.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Personally I have changed from 3/4" to 1" under a slab when we ran out of 3/4" The bell end of 3/4" fits perfectly into the bell end of 1" and glues up tight.
At least that's a transition that can readily be fished through. You have a bevel from either direction.

A pipe in a pipe leaves a thick obstruction that will impede either the fishtape or the pulled conductors.
 
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