Im trying to determine/locate the portion of code that calls for safetys to be in the 120v starter circuit. For ex:
An Air handler has many safetys. it has been my understanding that most of these safetys have to be wired in series w/ the 120v starter circuit going to the overloads. that utilizing the controls system to shutdown the AHU on many of these safetys is not good enough & simply wouldn't work if the AHU were to be running in HAND mode.(unless they were in series w/ the motor starter)
My research has found the following:
NFPA 70 (NEC 2008) describes a safety device in series with a boiler being shown in series w/ the 120w power. (725.31) & (Exhibit 725.3)
There is also mention in the NEC under 430.74 which I believe to be relevant. These are pictured in exhibit(s) 430.14 & 430.15
It is my understanding that AHU saftey's such as fire/smoke detectors, high pressure switches, freezestats, etc... should all be wired in series with the fan motor(s). utilizing soley the controls systems to stop sending a run signal to the AHU is not enough.
Thoughts...? Opionions...? ANy further sugestions... I have looked through the NFPA 90A, NFPA91, & the NFPA 101 (life safety code)
An Air handler has many safetys. it has been my understanding that most of these safetys have to be wired in series w/ the 120v starter circuit going to the overloads. that utilizing the controls system to shutdown the AHU on many of these safetys is not good enough & simply wouldn't work if the AHU were to be running in HAND mode.(unless they were in series w/ the motor starter)
My research has found the following:
NFPA 70 (NEC 2008) describes a safety device in series with a boiler being shown in series w/ the 120w power. (725.31) & (Exhibit 725.3)
There is also mention in the NEC under 430.74 which I believe to be relevant. These are pictured in exhibit(s) 430.14 & 430.15
It is my understanding that AHU saftey's such as fire/smoke detectors, high pressure switches, freezestats, etc... should all be wired in series with the fan motor(s). utilizing soley the controls systems to stop sending a run signal to the AHU is not enough.
Thoughts...? Opionions...? ANy further sugestions... I have looked through the NFPA 90A, NFPA91, & the NFPA 101 (life safety code)