PVC on service entrance

[jetlag]

Hi all , on residential we are allowed in Georgia to use PVC conduit on
a service entrance as long as the service drop is not attached to it as
is the case when the weather ends on the side of the house and the
service drop is fastened to the structure. Of course if the service mast
goes through and above the roof to support the service drop it has to
be rigid conduit. My question is if I use a 10 ft. joint of 2" ridged to go
through the roof with 3 ft. above the roof and the other 7 ft. fastened
to the outside wall , is there any thing wrong with changing over to
PVC conduit from that point on to the outside disconnect ? I have to
do 2, 45 degree turns to get against the basement wall since the
rooms above are cantilevered out 15" .This will be much easier with
PVC. I remember in the code you can not have a joint coupling in the
mast or for a certain distance below the roof penetration , I believe that is 3 or 4 ft.
I don't see why you couldn't change to PVC below that point.

 

[curt swartz]

How are you planning to bond the metal portion?

 

[texie]

Hi all , on residential we are allowed in Georgia to use PVC conduit on
a service entrance as long as the service drop is not attached to it as
is the case when the weather ends on the side of the house and the
service drop is fastened to the structure. Of course if the service mast
goes through and above the roof to support the service drop it has to
be rigid conduit. My question is if I use a 10 ft. joint of 2" ridged to go
through the roof with 3 ft. above the roof and the other 7 ft. fastened
to the outside wall , is there any thing wrong with changing over to
PVC conduit from that point on to the outside disconnect ? I have to
do 2, 45 degree turns to get against the basement wall since the
rooms above are cantilevered out 15" .This will be much easier with
PVC. I remember in the code you can not have a joint coupling in the
mast or for a certain distance below the roof penetration , I believe that is 3 or 4 ft.
I don't see why you couldn't change to PVC below that point.

How would you bond the metallic raceway if it is just out there electrically floating? In theory it would seem that you could put a bonding jumper from the neutral to the riser pipe at the weather head and comply with 250.92. Can't imagine an AHJ or POCO allowing such a rig though.

 

[jetlag]

pvc

pvc

How would you bond the metallic raceway if it is just out there electrically floating? In theory it would seem that you could put a bonding jumper from the neutral to the riser pipe at the weather head and comply with 250.92. Can't imagine an AHJ or POCO allowing such a rig though.

Hey, thanks , I meant to say weather head where I had weather . I knew something did not seem right about that , here with the jumper they would flag that as paralleling the neutral . Looks like I will have to get the old pipe threader out . Thanks for replies.

 

[texie]

Hey, thanks , I meant to say weather head where I had weather . I knew something did not seem right about that , here with the jumper they would flag that as paralleling the neutral . Looks like I will have to get the old pipe threader out . Thanks for replies.

250.92 would allow this as anything metallic on the line side of the service disconnect can be bonded to the neutral. But as I said, this would be so non traditional I can't see it being done.

 

[ceb58]

Along with the bonding issue there was a discussion a long time ago about couplings in a service mast. Best I remember an inspector was turning down a install because the couplings are not listed. He was using 230.28 as a reference.

 

[augie47]

It has been done that way on rare occasions in this area with a bonding jumper installed on the weatherhead to the neutral. I would suggest discussing it with your POCO as they often question what is happening.

 

[kwired]

How would you bond the metallic raceway if it is just out there electrically floating? In theory it would seem that you could put a bonding jumper from the neutral to the riser pipe at the weather head and comply with 250.92. Can't imagine an AHJ or POCO allowing such a rig though.

Why, I have done exactly the same thing with underground PVC service raceways that emerge as metallic raceway, usually with a grounding bushing inside the enclosure it terminates to, but it is the same effective thing - that section of metal raceway need to be bonded.

Hey, thanks , I meant to say weather head where I had weather . I knew something did not seem right about that , here with the jumper they would flag that as paralleling the neutral . Looks like I will have to get the old pipe threader out . Thanks for replies.

If you only bond at one point you are not creating any parallel path.

 

[jetlag]

thanks wired

thanks wired

Why, I have done exactly the same thing with underground PVC service raceways that emerge as metallic raceway, usually with a grounding bushing inside the enclosure it terminates to, but it is the same effective thing - that section of metal raceway need to be bonded.

If you only bond at one point you are not creating any parallel path.

I agree but tell that to the local inspectors, they claim that is using the metal conduit to form a parallel neutral . I was in an area where copper theft was bad so I put the #4 ground to the ground rod in a piece of 1/2 EMT from the disconnect down to the ground about 2 feet so they couldn't just walk up and clip the ground wire and I got flagged on that for paralleling the ground and had to change that to pvc . Strangely enough most of the post agreed with the inspector . The but best I can remember the reason was something different than what the inspector flaged me for . Maybe something to do with harmonics .

 

[augie47]

I agree but tell that to the local inspectors, they claim that is using the metal conduit to form a parallel neutral . I was in an area where copper theft was bad so I put the #4 ground to the ground rod in a piece of 1/2 EMT from the disconnect down to the ground about 2 feet so they couldn't just walk up and clip the ground wire and I got flagged on that for paralleling the ground and had to change that to pvc . Strangely enough most of the post agreed with the inspector . The but best I can remember the reason was something different than what the inspector flaged me for . Maybe something to do with harmonics .

That (the grounding electrode conductor in metallic conduit) was recently discussed here:
http://forums.mikeholt.com/showthread.php?t=160037

 

[kwired]

I agree but tell that to the local inspectors, they claim that is using the metal conduit to form a parallel neutral . I was in an area where copper theft was bad so I put the #4 ground to the ground rod in a piece of 1/2 EMT from the disconnect down to the ground about 2 feet so they couldn't just walk up and clip the ground wire and I got flagged on that for paralleling the ground and had to change that to pvc . Strangely enough most of the post agreed with the inspector . The but best I can remember the reason was something different than what the inspector flaged me for . Maybe something to do with harmonics .

Your inspector needs to go back to school and take a basic electricity course. How is he going to get parallel current if he only has one point of bonding?

If you bonded the top of that mast to the grounded conductor in the service drop and then bonded the bottom end to the meter socket - then you would have that piece of rigid carrying parallel current of the grounded conductor. Otherwise the raceway is just bonded to the grounded conductor to put them at the same potential and is not carrying any current.

If you have the typical rigid mast all the way up from the meter socket you have the same thing, but reversed, the bond is at the meter socket and you do not bond the top of the raceway to the service drop. The raceway is still bonded but not in a parallel fashion.

If copper thieves are stealing copper from near the point of attachment, you have problems well beyond NEC.

The steel raceway enclosing a grounding electrode conductor is not unacceptable, but you must bond the GEC to both ends of the raceway to reduce inductive effects developed in that steel raceway. That is not the same thing as making a parallel conductor for the service grounded conductor, and the use of EMT emerging out of the ground is another issue related to suitability of use and not part of a grounding or bonding issue.

 

[GoldDigger]

The restrictions in the NEC on parallel conductors apply only to current carrying conductors, not to the GEC, and as discussed in the mentioned thread the other code issue involves requiring the creation of a parallel path.


Tapatalk!

 

[Bigjoe1947]

PVC use

PVC use

As long as the PVC is not subject to a driveway where a car can travel I see no problem.If there is a driveway and you use PVC you must use a protective covering. Save the problem use rigid all the way.

 

[kwired]

As long as the PVC is not subject to a driveway where a car can travel I see no problem.If there is a driveway and you use PVC you must use a protective covering. Save the problem use rigid all the way.

Welcome to the forum,
Now that that is done, sorry but if a vehicle is what is the potential physical damage, then RMC is not even stout enough to withstand what it may be in for. This is generally not much of a problem with residential driveways, but is a common problem where there is forklifts, front end loaders, or other similar vehicles in an area with any raceway exposed to the vicinity of operation. Even concealed wiring in walls or on the back side of a wall is not always safe as these vehicles and their operators find a way to trash the walls sometimes.

 

[jap]

I agree but tell that to the local inspectors, they claim that is using the metal conduit to form a parallel neutral . I was in an area where copper theft was bad so I put the #4 ground to the ground rod in a piece of 1/2 EMT from the disconnect down to the ground about 2 feet so they couldn't just walk up and clip the ground wire and I got flagged on that for paralleling the ground and had to change that to pvc . Strangely enough most of the post agreed with the inspector . The but best I can remember the reason was something different than what the inspector flaged me for . Maybe something to do with harmonics .

If you didnt have a bonding bushing on the end of the 1/2" emt ,thats probably why you got flagged. Running a single grounding electrode conductor through a ferrous raceway creates a choke if not. thats probably why he had you change it to pvc instead of the parallel grounding thing.

 

[electrofelon]

Just a reminder that the NEC doesnt use the term "parallel path" in terms of service conductors. It does for an SDS but not for the service. The whole "one bond point" concept is not a specific code requirement.

 

[kwired]

Just a reminder that the NEC doesnt use the term "parallel path" in terms of service conductors. It does for an SDS but not for the service. The whole "one bond point" concept is not a specific code requirement.

True, but going back to the OP only one bond point would help eliminate any paralleling and creating unintended current carrying via the raceway. Now if the raceway is mounted to a grounded surface there is going to be current flow no matter what, but NEC wouldn't see that as objectionable current flow. Same thing happens if you have a metallic raceway between a meter socket and the service disconnecting means, that raceway is connected in parallel to the grounded service conductor and does share grounded conductor current.