Low voltage piped with 120v

[davewants2]

I inspected a home built in 1976 and found low voltage control wiring for air conditioning system had been piped in emt with supply wiring. A/C equipment was replaced in 1992. I gave my opinion that control wiring should have been upgraded / run out side emt when A/C was replaced. Am I wrong? Does any one know when this rule was changed in the NEC and wouldn't the code in effect at the time of replacement govern?

 

[daverz]

Re: Low voltage piped with 120v

According to the 1990 NEC (725-15), this installation is allowed as long as the insulation on all of the conductors is rated for the maximum voltage of any of the conductors, AND the equipment powered by both sets of conductors is functionally associated.

 

[don_resqcapt19]

Re: Low voltage piped with 120v

Dave,
725-15 only applies to Class 1 remote control circuits. All residential HVAC control circuits that I have ever seen are Class 2 circuits and cannot be combined with power circuits.
Don

 

[davewants2]

Re: Low voltage piped with 120v

Don
Can you give me more info such as the year this change took place or are you saying it was never allowed by the NEC ? Thanks for any help you can give.

 

[tom baker]

Re: Low voltage piped with 120v

Davertz:
While we read 300.3(C)(1) we neglect the FPN to 725.54. 725.54 states separation is required for a class 2 circuit.
See section 90.3 for the how Chapter 7 works with the rest of the NEC. Its assumed you know 90.3 when you read the code, esp Art 725, and chaper 8.
I don't know how long this has been in the code, but I suspect a very long time.