Hvac disconnect

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mkgrady

Senior Member
Location
Massachusetts
I checked out a hvac unit today in an apartment in a large apartment building to see why a recently installed unit was tripping the breaker. That answer was simple. It was connected to a 2 pole 30. MCA for it is 47. So the branch circuit needs to be upgraded to a 50 amp circuit. Obviously an electrician did not wire it. Someone just connected a new unit to the existing circuit.

My question is about the disconnect. There wasn't one within site of the unit. All there is is a circuit breaker for it in a different room. There was no sign of a means to lock the breaker in the off position. Doesn't the unit need a disconnect within site?
 
Here's the requirement from Article 440, within sight unless it meets the exceptions:

440.14 Location. Disconnecting means shall be located
within sight from and readily accessible from the air-
conditioning or refrigerating equipment. The disconnect-
ing means shall be permitted to be installed on or within
the air-conditioning or refrigerating equipment.
The disconnecting means shall not be located on panels
that are designed to allow access to the air-conditioning or
refrigeration equipment or to obscure the equipment name-
plate(s).
Exception No. 1: Where the disconnecting means provided
in accordance with 430.102(A) is capable of being locked in
the open position, and the refrigerating or air-conditioning
equipment is essential to an industrial process in a facility
with written safety procedures, and where the conditions of
maintenance and supervision ensure that only qualified per-
sons service the equipment, a disconnecting means within
sight from the equipment shall not be required. The provision
for locking or adding a lock to the disconnecting means shall
be installed on or at the switch or circuit breaker and shall
remain in place with or without the lock installed.
Exception No. 2: Where an attachment plug and recep-
tacle serve as the disconnecting means in accordance with
440.13, their location shall be accessible but shall not be
required to be readily accessible.
Click to expand...
 
The 30 amp feed to it is not the same cable at the panel so there must be a hidden splice somewhere. The 10-2 Romex cable feeding it comes through the connecting duct work. Isn't that a problem? The splice is probably in the duct work.
 
Yes, non plenum rated wiring inside an air duct (other than an exhaust duct to outside) is very severely restricted.
Sounds like a hack job during construction or when remodeling.
 
GoldDigger said:
Yes, non plenum rated wiring inside an air duct (other than an exhaust duct to outside) is very severely restricted.
Sounds like a hack job during construction or when remodeling.
Click to expand...

I don't know why the feed comes in through the duct work but assuming there is a good reason is mc allowed in ductwork? I will be recommending they run a new 8-2mc cable. Can this be run through hvac duct?
 
mkgrady said:
I don't know why the feed comes in through the duct work but assuming there is a good reason is mc allowed in ductwork? I will be recommending they run a new 8-2mc cable. Can this be run through hvac duct?
Click to expand...

Can not be. See 300.22(B)
 
My guess is the HVAC installer put in a new unit, used old circuit that was not sufficient to supply the unit. Probably worked fine until the heat strip was called upon for duty.
 
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