Old wiring to an AC unit

[goldstar]

I recently had a service call to repair wiring to an AC compressor. An aluminum SE cable was used to power the 40 amp unit. It was run inside the condo walls and ran (in open air) to the compressor for about 12 feet to a disconnect mounted on the side of the unit. A (makeshift)wooden enclosure was built to cover both the condensor and power lines. This was typical for all the condo units. It seems that 17 years ago (when this condo complex was built) a siding contractor drove a nail through an SE cable feeding the AC unit. As far as I can tell the initial penetration went through one of the phase conductors and burnt a portion of the braided EGC. The nail also partially penetrated the insulation of the second phase conductor. After all this time the insulation finally broke down and burnt up the cable.

My question is whether aluminum SE cable was ever allowable by the NEC for this purpose and installed in this manner. The whole installation seemed shoddy to me but somehow they managed to build an entire complex this way.

 

[charlie]

Re: Old wiring to an AC unit

My question is whether aluminum SE cable was ever allowable by the NEC for this purpose and installed in this manner.

The SE cable was supported and protected according to the NEC at the time of installation. I assume (I never have liked that word) the installations were approved by an AHJ since the whole project was done the same way.

If a siding contractor did this 17 years ago, the condos were (most likely) built another 15 years or so before that for them to put siding on the units.

The question I have is, what is the violation?

 

[goldstar]

Re: Old wiring to an AC unit

Charlie,

Thanks for your reply. I'm not sure there was a code violation.......that's why I asked. I don't go back that far with this type of installation so I'm not aware of what was acceptable and when. But also, just because an AHJ inspected it doesn't make it right.

I misspoke when I said it was the siding contractor who put the nail through the cable. It was when the sheething was installed that the nail went through. The electrician ran the SE cable alongside the AC condensor lines. Although the studs were notched out there were no nail plates used so it wasn't the framer's fault either. The SE cable left the house and ran (on the ground) next to the condensor lines to the AC unit and a wooden enclosure was built around both lines. I was under the impression that the right way to do this was to install the disconnect on the house and run a whip in seal-tight to the unit.

As a personal preference I wouldn't use aluminum SE cable to feed a 4 ton AC unit mainly because of the characteristics of aluminum (expansion and contraction and loosening of the terminals). In this case the wire not only shorted between both phases but also melted. My feeling is that if it were copper wire it would have blown the breaker long before it melted and broke apart.