Contractor dug into a rigid conduit with THHN wire supplying power to a backflow heater. Contractor said code allowed him to splice and repair the wiring at that point. Contractor butt spliced, taped, applied heat shrink and installed a PVC sleeve over the damaged area. The conductors are not listed for direct burial but the contractor maintains that the installation falls under the direct burial method and therefore qualifies for a splice without using a box. I do not believe that the NEC defines a rigid conduit with THHN conductors as a direct burial method and the splice should be made with the methods defined for the conditions.
Underground Wiring Methods
- Thread starter joehaake
- Start date
- Status
- Location
- Bremerton, Washington
THHN is not a listed direct burial wire.
11014.B has the requirements for splices, but it does not apply to splices in a raceway
We all know a box is required for splices, but at the moment I can't find the code section.
11014.B has the requirements for splices, but it does not apply to splices in a raceway
We all know a box is required for splices, but at the moment I can't find the code section.
- Occupation
- Licensed Electrician
He is wrong.
You are not supposed to splice conductors inside conduit, you need a box. THHN/THWN is not direct bury wire, and he needs to make the metallic raceway complete, not scab it together with PVC.
You are not supposed to splice conductors inside conduit, you need a box. THHN/THWN is not direct bury wire, and he needs to make the metallic raceway complete, not scab it together with PVC.
kwired
Electron manager
- Location
- NE Nebraska
He didn't splice them in the conduit, he spliced them in the sleeve he put over the damaged area
One of my bigger concerns is if that RMC were serving as the equipment ground for the contained circuit(s) you now don't have an EGC.
- Location
- Massachusetts
He didn't splice them in the conduit, he spliced them in the sleeve he put over the damaged area
This is not helpful to the OP, it leads to confusion.
Let's make it clear, yon can't splice THHN underground in a raceway or a sleeve.
ptonsparky
Tom
- Occupation
- EC - retired
The THWN I have a problem with but IDK why I should. The wires most likely lay in water a good share of the year, if not all of it. No different than the splices I make every year in the middle of damaged pivot/well services that just happen to be DB rated but are in conduit. We use kits to repair the conduit and staggered butt splices with heat shrink in the conduit to repair the wire. I would hate to be within rifle range when the owner learned he must now farm around those two junction boxes.
- Location
- Massachusetts
Seems like the type of installation that is well served by using DB rated conductors.
I agree THHN is often underwater but it is also not very tough at all when it comes to damaging it enough to cause a failure from water.
What I am trying to say is when in a pipe with no chance of damage it lasts fine underwater. But direct buried I would say it is very likely to be damaged by a rock or something.
ptonsparky
Tom
- Occupation
- EC - retired
Seems like the type of installation that is well served by using DB rated conductors.
I agree THHN is often underwater but it is also not very tough at all when it comes to damaging it enough to cause a failure from water.
What I am trying to say is when in a pipe with no chance of damage it lasts fine underwater. But direct buried I would say it is very likely to be damaged by a rock or something.
Is the THWN direct buried if the conduit was repaired with kit designed for the purpose? In the OPs case a sleeve most likely fails that test.
JFletcher
Senior Member
- Location
- Williamsburg, VA
314.16(C), 344.56-->300.15
- Status