NEC Code

[Nightwolf]

Hello,

I just have a quick question. Would it be a code violation if a disconnect switch was physically placed inside a building, but the motor was roof mounted?

 

[jlhmaint]

What is the motor for, i dont have my NEC book with me right now but i believe that you have to have a disconnet within site of the motor but there are exceptions to this. However if you are going to have to service the motor or belts later i would put a disconnect with the motor it is much safer this way and your maintenance man wont have to go from the roof to the shop floor when working on the motor.

 

[dpc]

In general, you need a disconnect at the motor for roof-mounted equipment. You also are required to provide a 120V receptacle for maintenance.

 

[resqcapt19]

The general rule is that the disconnect must be within sight of the motor. See 430.120
"(B) Motor. A disconnecting means shall be located in sight from the motor location and the driven machinery location. The disconnecting means required in accordance with 430.102(A) shall be permitted to serve as the disconnecting means for the motor if it is located in sight from the motor location and the driven machinery location.
Exception: The disconnecting means shall not be required to be in sight from the motor and the driven machinery location under either condition (a) or (b), provided the disconnecting means required in accordance with 430.102(A) is individually capable of being locked in the open position. The provision for locking or adding a lock to the disconnecting means shall be permanently installed on or at the switch or circuit breaker used as the disconnecting means.
(a) Where such a location of the disconnecting means is impracticable or introduces additional or increased hazards to persons or property
(b) In industrial installations, with written safety procedures, where conditions of maintenance and supervision ensure that only qualified persons service the equipment"

This was a major change in the 2002 code. In the '99 code the motor disconnect could be deleted any time the motor controller disconenct required by 430-102(A) was capable of being locked in the open position. Now you also have to comply with (a) or (b) above before you can delete the local disconnect. The effect of the '02 code change is to require many more motors to have local disconnects. In my opinon, the word "impracticable" in (a) does not mean you can delete the disconnect just because of the cost of installing it.
Don

 

[Ares]

In Canada HVAC units are required to have local disconnects nothwithstanding any other rules of the code.
The reason - HVAC units are often serviced by people that do not necessarily are very familiar with electrical safety or electrical system in the facility they service.

 

[resqcapt19]

Ares,
Good point, the NEC also requires a local disconnect for all refrigeration and air conditioning equipment in Article 440. There is one exception for industrial process refrigeration equipment. Article 424 requires local disconnects for most heating equipment. Ventilating equipment is covered by the rules for motors in 430.
Don

 

[jbartos]

Suggestion: The safety codes stipulates minimum safety. If can use your ingenuity and challenge the safety code minimum safety by providing the same or better safety, you will be on the safe side. The question is how to provide the equivalent or better safety than the safety code calls for? One way to look at the local disconnect switch avoidance would be to build some cage around your roof motor and padlock it. The key to the motor could locked in a motor disconnect switch located elsewhere with location identified at the motor protection cage. If the key could be obtained only when the motor is disconnected and door open to obtain the key for the cage, then one would go to the roof motor with the motor deenergized. There would have to be another key arragement that would lock the disconnect in the open position and the key would also be then removable and needed to open the motor cage on the roof. If this all is implemented, the cost could be higher than the installation of the local disconnect at the motor on the roof.

 

[jlhmaint]

also that 120v outlet that is required has to be a GFCI.

 

[dubairay]

You are required to install a local disconnect at the motor! This is to ensure that work at the motor can be carried out safely.