LFNC Not Permitted scenarios

[ohmti787]

We've been running LFNC through attics all the way to the MSP since forever without any issues (for solar systems w/ micros). Now I have this inspector saying that we can't use this type of conduit because it's subject to physical damage. Is there any place in the code where it explains what the term "physical damage" actually means? As far as I'm concerned any piece of conduit can be subject to physical damage regardless of its location. Can someone shed some light on this please? Thanks

 

[infinity]

There is no standard for subject to physical damage so it's up to the guy looking at it to decide. What raceway did he offer as an alternative to LFNC?

 

[letgomywago]

Do the attics have MC or Romex in them in the same locations? If so is he planning on red tagging that install. If within 6ft of the access there should be running boards

 

[ohmti787]

There is no standard for subject to physical damage so it's up to the guy looking at it to decide. What raceway did he offer as an alternative to LFNC?

he's suggesting to use PVC sch80

 

[ohmti787]

Do the attics have MC or Romex in them in the same locations? If so is he planning on red tagging that install. If within 6ft of the access there should be running boards

they don't. we have a pretty clear path for that run all the way down to the MSP

 

[letgomywago]

they don't. we have a pretty clear path for that run all the way down to the MSP

Do you need a ladder to enter the attic?

 

[ohmti787]

Do you need a ladder to enter the attic?

yes, you do

 

[letgomywago]

yes, you do

I don't think many would feel the same as the inspector but idk if fighting it would work either.

 

[letgomywago]

Maybe ask which has more chance of physical damage an AC whip or a small conduit in an attic out of the path of travel.

 

[jaggedben]

The inspector is saying it's subject to physical damage ... where, exactly? Attic? Roof? Ground?

Sounds bizarre but I agree there's no solid basis for appeal.

 

[pv_n00b]

It's strange but it is an AHJ call. Neither "physical damage" or "severe physical damage" are defined in the NEC. It's the kind of thing I would have a discussion with the AHJ over to see if I can find out what the actual concern is. Right now they are giving their solution to their concern, but not sharing their concern. Usually in a case like this if you know what the concern is you can talk them back from the ledge.

 

[don_resqcapt19]

It's strange but it is an AHJ call. Neither "physical damage" or "severe physical damage" are defined in the NEC. It's the kind of thing I would have a discussion with the AHJ over to see if I can find out what the actual concern is. Right now they are giving their solution to their concern, but not sharing their concern. Usually in a case like this if you know what the concern is you can talk them back from the ledge.

That is intentional as the term "physical damage" is used with multiple wiring methods. Based on the rule in 334.15(B), I would require protection for the NM in locations that I would not require protection for schedule 40 PVC, yet the PVC is not permitted to be installed in locations where it would be subject to physical damage.
This is a subjective rule intended to permit the inspection authority to use some judgement.

Right now there are a lot of areas that I would prohibit NM without additional protection, but in the 70s or 80s I would have permitted the NM in those areas because of the huge difference in the jacket used back then was much more resistant to physical damage.

 

[mtnelect]

This might help to explain.

 

[mtnelect]

This might help to explain.

Section 351 has been moved to 350 in the 2023 NEC.

 

[don_resqcapt19]

Section 351 has been moved to 350 in the 2023 NEC.

LFNC has been in Article 356 for a long time. Article 350 is LFMC.

 

[pv_n00b]

That is intentional as the term "physical damage" is used with multiple wiring methods. Based on the rule in 334.15(B), I would require protection for the NM in locations that I would not require protection for schedule 40 PVC, yet the PVC is not permitted to be installed in locations where it would be subject to physical damage.
This is a subjective rule intended to permit the inspection authority to use some judgement.

Right now there are a lot of areas that I would prohibit NM without additional protection, but in the 70s or 80s I would have permitted the NM in those areas because of the huge difference in the jacket used back then was much more resistant to physical damage.

That's a way of looking at it I had not considered. The same threat of physical damage to NM may not be a threat to SCH 40 PVC in the same location. All the more reason to talk to the AHJ and find out what threat they are considering and discuss if that is a reasonable threat or not.

 

[kingpb]

Perhaps he's concerned with it getting walked on. Discuss with him that you aren't going to just lay it across joists and not run it where it can get walked on.

I would be more concerned with heat. The attic can get up to 150degF. Combined with the the conductor temps running at full load, have you de-rated properly? Is the temp below the rating of the LFNC.