Residential garage

[dm9289]

The basement/ garage area of a common “A” frame home in my area has a steel beam running thru the center of the home at a 90 degree angle to floor joists. In the basement laundry part bored holes are common rules pretty straight forward.

But the typical garage has a finished ceiling and the nm cables are attached/ bundled between finished ceiling and steel beam exposed. Is this code compliant?

After the steel beam ends wires are bundled run along wall finished ceiling height to service panel drop about a foot then enter panel is this OK

334.15C gives some good info as does 300.4 but I’m having trouble. With the garages here having finished ceilings and the above methods seeming so common and probably incorrect is what causes me confusion

Thanks for your help

 

[kwired]

The basement/ garage area of a common “A” frame home in my area has a steel beam running thru the center of the home at a 90 degree angle to floor joists. In the basement laundry part bored holes are common rules pretty straight forward.

But the typical garage has a finished ceiling and the nm cables are attached/ bundled between finished ceiling and steel beam exposed. Is this code compliant?

After the steel beam ends wires are bundled run along wall finished ceiling height to service panel drop about a foot then enter panel is this OK

334.15C gives some good info as does 300.4 but I’m having trouble. With the garages here having finished ceilings and the above methods seeming so common and probably incorrect is what causes me confusion

Thanks for your help

I am having a hard time understanding what you are describing in bold print above.

Steel beam is presumably there to support ceiling framing members as they probably aren't rated to span wall to wall, how is it you have a space between it and the ceiling to bundle the cables?

 

[augie47]

The word "bundled" raises eyebrows...watch 310.15(B)(3) !

 

[dm9289]

Typically in this area a wooden beam is on top of steel beam and it is attached between steel wood and ceiling

 

[kwired]

Typically in this area a wooden beam is on top of steel beam and it is attached between steel wood and ceiling

So you essentially have a wood beam below and supporting the joists, and an additional steel beam below and supporting it? Don't see what is gained by that but not really relevant to your question either. I take it cables in question are attached to this wood beam? If AHJ considers them protected from physical damage then it is probably fine to run them there. Whether or not they are considered bundled or not may require you apply ampacity adjustments.

 

[dm9289]

 

[kwired]

View attachment 22251

Your "wood beam" is more of a continuous "shim" than it is a beam. It alone is not adding strength to the beam. But is now clear what you were describing. In that image I'd say that cable is not exposed after finish is put on those vertical strips. Could possibly need protection nail plates if not over 1-1/4 inch from face of strip to the cable though.

 

[dm9289]

The word "bundled" raises eyebrows...watch 310.15(B)(3) !

Yes if you look at the beam picture I posted it would be similar to that with a drywall ceiling. Lets say 8 NM cables typically tie wrapped to create the bundle. I am not sure how to derate no conduit

 

[dm9289]

The picture I posted is an example of the beam but the finished garage ceiling is what is different. Typically you will see 8 NM cables tie wrapped across the beam then 90 degree angle attached in corner of ceiling and block wall then a 90 downward to panel. Hope this clears my description up.

 

[jap]

I honestly don't see how NM ever survives at all.

You would think the wiring methods designed for a dwelling type installation would be more robust.

Oh well,,,,


JAP>

 

[kwired]

Yes if you look at the beam picture I posted it would be similar to that with a drywall ceiling. Lets say 8 NM cables typically tie wrapped to create the bundle. I am not sure how to derate no conduit

Same way you "derate" conductors in a conduit. If you have eight 12-2 cables bundled together you have 16 current carrying conductors and adjustment factor for that is 50%.

If you break it into two separate bundles and maintain spacing so that it remains as two separate bundles now you only have 8 current carrying conductors in each bundle and adjustment is 70% - that works out to not needing to increase conductor size for NM-B.

Reality is you probably never produce enough heat to be an issue unless they are all feeding HVAC or other continuous loads, but that is not what NEC says....:blink:

 

[hbiss]

The picture I posted is an example of the beam but the finished garage ceiling is what is different. Typically you will see 8 NM cables tie wrapped across the beam then 90 degree angle attached in corner of ceiling and block wall then a 90 downward to panel. Hope this clears my description up.

Nope. Even more confusing. How about a picture?

-Hal

 

[sameguy]

3M cable stackers, but you can bundle w/ tywraps.

 

[GerryB]

The basement/ garage area of a common “A” frame home in my area has a steel beam running thru the center of the home at a 90 degree angle to floor joists. In the basement laundry part bored holes are common rules pretty straight forward.

But the typical garage has a finished ceiling and the nm cables are attached/ bundled between finished ceiling and steel beam exposed. Is this code compliant?

After the steel beam ends wires are bundled run along wall finished ceiling height to service panel drop about a foot then enter panel is this OK

334.15C gives some good info as does 300.4 but I’m having trouble. With the garages here having finished ceilings and the above methods seeming so common and probably incorrect is what causes me confusion

Thanks for your help

If you are saying they are only bundled for a foot then you are ok. That is the same as a sleeve less than 24" NEC 310.15(B)(3) in 2014, adjustment factors, more than 3 current carrying conductors.