NM and NEC in the 1980's

[dancase]

I've got an HVAC condensing unit that was installed in the mid 1980's. It's fed by #10/2 NM from the main breaker panel on the outside of the building (I hate that, but it's common here) The first 3 feet are sleeved n liquid-tight flex that ends just inside the crawlspace. The NM exits the crawl space sleeved in EMT for about 3 feet to the raintight disconnect.

Obviously non-compliant.

However, I find myself wondering if it was code compliant back in the 80's when it was installed. If so, it's grandfathered (ugly, but not mandatory replacement). I seem to recall reading somewhere that there was a day when these short runs of sleeved NM would have been acceptable under NEC--or maybe it was someone arguing that it should be.

I'd love to rip this out and replace it, but it's working fine as-is and since we're talking about my money instead of someone else's (I own the house) I'd prefer to leave it for more prosperous times.

Was there ever a time when this would have met code?

Thanks!

D.

 

[Ponchik]

I believe this was a change for the 2008 cycle. Basically saying that the inside of the conduit is wet location.

However, you will still have conduit on the surface of the building coming out from the crawl space going into the A/C unit. Whether it is EMT with single conductors in it or a LTFNMC with NM cable in it you still have a conduit on the surface of the building.

Unless you don't like the look of the LTFNMC.

 

[fmtjfw]

I've got an HVAC condensing unit that was installed in the mid 1980's. It's fed by #10/2 NM from the main breaker panel on the outside of the building (I hate that, but it's common here) The first 3 feet are sleeved n liquid-tight flex that ends just inside the crawlspace. The NM exits the crawl space sleeved in EMT for about 3 feet to the raintight disconnect.

Obviously non-compliant.

However, I find myself wondering if it was code compliant back in the 80's when it was installed. If so, it's grandfathered (ugly, but not mandatory replacement). I seem to recall reading somewhere that there was a day when these short runs of sleeved NM would have been acceptable under NEC--or maybe it was someone arguing that it should be.

I'd love to rip this out and replace it, but it's working fine as-is and since we're talking about my money instead of someone else's (I own the house) I'd prefer to leave it for more prosperous times.

Was there ever a time when this would have met code?

Thanks!

D.

Might be OK. Some old NM uses TW conductors. Look at the conductors and see if they are marked TW.

 

[Steviechia2]

Might be OK. Some old NM uses TW conductors. Look at the conductors and see if they are marked TW.

I believe the issue is with the paper inside of the sheathing. If it gets wet than it does not dry out and then there is a corrosion problem with the bare copper conductor

 

[kwired]

I believe this was a change for the 2008 cycle. Basically saying that the inside of the conduit is wet location.

However, you will still have conduit on the surface of the building coming out from the crawl space going into the A/C unit. Whether it is EMT with single conductors in it or a LTFNMC with NM cable in it you still have a conduit on the surface of the building.

The interior of raceways installed outdoors has been a wet location for a very long time. Whatever change you mentioned that was made in 2008 NEC was likely just a clarification more so than a change.

Unless you don't like the look of the LTFNMC.

Might be OK. Some old NM uses TW conductors. Look at the conductors and see if they are marked TW.

That means the individual conductors are rated for wet location, the entire cable assembly is still a dry location only assembly.