Existing raceway and strapping

[Kaia8172006]

Commercial remodel: we are adding a room in a back warehouse and there is a raceway with existing wires running from panel to a junction box 30’ away that is 10ft off the floor strapped to wall. Conduit runs out of panel box up 20’ and is strapped to corrugated ceiling continues for 30’ and then comes down on wall to junction box. We planned to tap into the junction box to feed lights for new room. The circuit feeding the junction box is not being used. Electrical inspector said we can’t tap into the junction box because the conduit is strapped to the ceiling and needs to be moved 3” down from ceiling or to run a new raceway and pull new wires. I always thought if raceway was existing and wire are existing you can use the box as long as you stay at least 3” down from the box. As junction box is 10ft down from ceiling so we would be way below. Does anyone know the code about conduit and strapping and wether we can use the junction box? I don’t think electrical inspector is interpreting the code correctly. Thanks

 

[ActionDave]

If the existing conduit was installed correctly under the code that was adopted at the time of installation then I don't see where the inspector has anything to say about it. I think the rule to be below the ceiling came around 2011.

 

[AC\DC]

So we can’t have j-boxes attached to a ceiling??? Am I reading that wrong? Can I get the code section

 

[ActionDave]

300.4 Protection Against Physical Damage​

(E) Cables, Raceways, or Boxes Installed in or Under Roof Decking​

A cable, raceway, or box, installed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so there is not less than 38 mm (11/2 in.) measured from the lowest surface of the roof decking to the top of the cable, raceway, or box. A cable, raceway, or box shall not be installed in concealed locations in metal-corrugated, sheet decking—type roof.
Informational Note: Roof decking material is often repaired or replaced after the initial raceway or cabling and roofing installation and may be penetrated by the screws or other mechanical devices designed to provide "hold down" strength of the waterproof membrane or roof insulating material.
Exception: Rigid metal conduit and intermediate metal conduit shall not be required to comply with 300.4(E).

 

[AC\DC]

I’ll have to remember that. Neve attached to metal corrugated roof before.
Makes sense though

 

[ActionDave]

I don't know why roofers need to use screws as long as your forearm to secure the foam backing they use under their roof membrane.

 

[Buck Parrish]

Why are they saying three inches when that code article states an inch and a half below ?

 

[electrofelon]

I’ll have to remember that. Neve attached to metal corrugated roof before.
Makes sense though

A couple things about that section though:. It's hard for me to imagine a situation where one would strap to corrugated roof decking. Note a "ceiling" is not necessary roof decking. If someone use corrugated metal as the finish material on the inside, that is not roof decking. The only time I can remotely conceive of strapping right to the decking is if there was foam insulation on top so you knew you could Pierce screws through it without compromising the membrane. Not sure about other places but that is an uncommon roof method here, and besides there would be purlins that one would be strapping their conduit too, not directly to the corrugated decking.

 

[ActionDave]

Foam insulation and epdm membrane over corrugated steel panels has been s.o.p. for commercial roofs forever. We used to run EMT in the channels perpendicular to the roof truss all day long. If you got good you could couple three or four sticks and shove them down the line before you had to move your lift and you didn't have to strap. You could put screws anywhere you needed because the foam kept you away from the roof membrane.

 

[electrofelon]

Foam insulation and epdm membrane over corrugated steel panels has been s.o.p. for commercial roofs forever. We used to run EMT in the channels perpendicular to the roof truss all day long. If you got good you could couple three or four sticks and shove them down the line before you had to move your lift and you didn't have to strap. You could put screws anywhere you needed because the foam kept you away from the roof membrane.

Okay yeah, now that I think of it of course something like a home Depot/walmart/big box store that's what the roof is...... All the commercial buildings I have personally worked on where plywood or car decking so that was a little bit out of my mental Rolodex. Interesting that section doesn't apply to wood decking, that's odd

 

[Kaia8172006]

A couple things about that section though:. It's hard for me to imagine a situation where one would strap to corrugated roof decking. Note a "ceiling" is not necessary roof decking. If someone use corrugated metal as the finish material on the inside, that is not roof decking. The only time I can remotely conceive of strapping right to the decking is if there was foam insulation on top so you knew you could Pierce screws through it without compromising the membrane. Not sure about other places but that is an uncommon roof method here, and besides there would be purlins that one would be strapping their conduit too, not directly to the corrugated decking.

The roof on the building is flat and there is a layer of foam between the outer layer of roof and the inner corrugated metal ceiling.

 

[electrofelon]

The roof on the building is flat and there is a layer of foam between the outer layer of roof and the inner corrugated metal ceiling.

Ok so the foam is fastened to the corrugated stuff? Are there fasteners sticking thru? If so It does sound like that section applies then.

 

[rc/retired]

The roof on the building is flat and there is a layer of foam between the outer layer of roof and the inner corrugated metal ceiling.

Sorry. It doesn't matter. Good luck.

Ron

 

[AC\DC]

If how I read it his description of the roof it’s seems like electro said it’s a ceiling, not a roof decking so it does not apply

 

[Kaia8172006]

300.4 Protection Against Physical Damage​

(E) Cables, Raceways, or Boxes Installed in or Under Roof Decking​

A cable, raceway, or box, installed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so there is not less than 38 mm (11/2 in.) measured from the lowest surface of the roof decking to the top of the cable, raceway, or box. A cable, raceway, or box shall not be installed in concealed locations in metal-corrugated, sheet decking—type roof.
Informational Note: Roof decking material is often repaired or replaced after the initial raceway or cabling and roofing installation and may be penetrated by the screws or other mechanical devices designed to provide "hold down" strength of the waterproof membrane or roof insulating material.
Exception: Rigid metal conduit and intermediate metal conduit shall not be required to comply with 300.4(E).

 

[hillbilly1]

It’s quite a problem, I know of many building re-roofs where they drove screws into the conduits that were ran in the grooves. Happens so much, a large big box customer wanted me to come up with a way to easily locate and mark the roof so they could avoid running screws into them.

 

[Kaia8172006]

My question still remains. The emt conduit raceway is existing and strapped to corrugated ceiling and then drops down to junction box on wall that is 10’ below corrugated ceiling. Can we tap into junction box with existing wires without having to lower the existing raceway to comply with 300.4? Inspector is says that if we tap into junction box we are adding on to circuit (which isn’t even being used) and need to bring entire taceway that is strapped to ceiling up to code. I have asked other electrical inspectors in neighboring cities and the said it is perfectly fine to tap into an existing junction box whose raceway is strapped to corrugated ceiling as long as the new line coming out of junction box complies to 300.4. Does anyone know intent of code for conduit raceways that already exist?

 

[electrofelon]

My question still remains. The emt conduit raceway is existing and strapped to corrugated ceiling and then drops down to junction box on wall that is 10’ below corrugated ceiling. Can we tap into junction box with existing wires without having to lower the existing raceway to comply with 300.4? Inspector is says that if we tap into junction box we are adding on to circuit (which isn’t even being used) and need to bring entire taceway that is strapped to ceiling up to code. I have asked other electrical inspectors in neighboring cities and the said it is perfectly fine to tap into an existing junction box whose raceway is strapped to corrugated ceiling as long as the new line coming out of junction box complies to 300.4. Does anyone know intent of code for conduit raceways that already exist?

My question still remains if 300.4 covers this ceiling. Are there fasteners sticking through it?

As far as your question, unfortunately the NEC doesn't really get into the nuances of when something is considered existing or not. IMO if the conduit and conductors were there before that code requirement was, then it's okay to use them, but it is not my opinion that matters. I think you're only option is to ask for a second opinion from the chief electrical inspector or whoever is above this guy.

 

[Kaia8172006]

Ok so the foam is fastened to the corrugated stuff? Are there fasteners sticking thru? If so It does sound like that section applies then.

There are no fasteners sticking through on underside of corrugated ceiling.

 

[electrofelon]

There are no fasteners sticking through on underside of corrugated ceiling.

That makes me question whether the construction is such that 300.4 covers the installation. It could be glued down, but maybe there are purlins of some sort, I would investigate further.