Fused disconnect switch

[k88888]

1. When is a fused disconnect switch should be used? Other than refrigeration equipment.

2. Does a group of motors requires a single fused disconnect switch from a motor control panel? (ie., cooling tower).

3. Does an outdoor mechanical equipment requires a fused disconnect switch?

NEC code requirement please.

thanks

 

[jbartos]

Suggestion (in compliance with NFPA 70-1999, National Electrial Code (NEC)):
1a. Article 430-127 Disconnecting Means
(Electric Motor Controller) The controller disconnecting means shall be capable of being locked in the open position. (This is just good to know.)
1b. Article 430 J. Disconnecting Means
430-101 General.
Part J is intended to require disconnecting means capable of disconnecting motors and controllers from the circuit. (The diconnect may be fused or unfused!)
1c. 430-102 Location
a. Controller. An individual disconnecting means shall be provided for each controller. The disconnecting means shall be located in sight from the controller location.
2a. Exception No. 2: A single disconnecting means (Fusible or nonfusible!) shall be permitted for a group of coordinated controllers that drive several parts of a single machine or a piece of apparatus. The disconnecting means shall be located in sight from the machine or apparatus.
1d. A separate disconnecting means shall be located in sight from the motor location and the driven machinery location. Exception: A disconnecting means, in addition to the controller disconnecting means as required in accordance with Section 430-102a, shall not be required for the motor where the disconnecting means for the controller is individually capable of being locked in the open position.
2b. 430-103 Operation. .... The disconnecting means shall be permitted in the same enclosure with the controller.
1e. 430-107 Readily Accessible. One of the disconnecting means shall be readily accessible.
1f. Disconnecta are needed for:
422 C
422-30 General. A means shall be provided to disconnect each appliance from all ungrounded conductors in accordance with the following sections of Part C. If an appliance is supplied by more than one source, the disconnecting means shall be grouped and identified.
424 C Control and Protection of Fixed Electric Space Heating Equipment
424-19 Disconnecting Means.
668-13 Disconnecting Means. (a) More than One Process Power Supply. Where more than one dc cell process power supply serves the same cell line, a disconnecting means shall be provided on the cell line circuit side of each power supply to disconnect it from the cell line circuit.
669-8 Electroplating Systems
620-F and 620-51 Elevators
240-40 Fuses and Termal Cutouts
655-43 Induction and Dielectric Heating Equipment
645-2(a) and 645-10 Information Technology Equipment
705-20 and 705-21 Interconnected Electric Power Production Sources
3a. (Pertaining to your last question)
675-8 Disconnecting Means (Article 675 Electrically Driven of Controlled Irrigation Machines)
(b) Disconnecting Means. The main disconnecting means for the machine shall provided overcurrent protection (short-circuit protection) and shall be at the point of connection of electrical power to the machine or shall be visible and not more than 50 ft (15.2 m) from the machine and shall be readily accessible and capable of being locked in the open position.
550-6 Mobile Homes
680-12 Pools, spas and hot tubs
551-45 Recreational vehicles
250-32d Separate building on the same premises
230-F Services
600-6 Signs and outline lighting
630-33 Welders, resistance
517-72, 660-5, 660-24 X-ray equipment

By evidencing the safety intensity above, incorporated in the NFPA 70, may I suggest that you actually possess NFPA 70, since it may pay off for you and others in your profession. I wish that I contributed to a common safety a little by the above excerpts.
[sig][/sig]

 

[k88888]

JBartos:

Thanks for the excerpts, am a bit versed with the requirements from those excerpts. I just want to make sure i don't miss any code requirement other than refrigeration and elevator equipments that requires a fused disconnect. [sig][/sig]

 

[jbartos]

You are welcome. May I suggest that you do not "make sure" in safety areas over public forum. It is much safer to actually be versed with the content without any reliance on the public forum since the public forum will not be signing any contract for you; therefore, it will not be liable for anything. Wherever, brief references were made to the code, it was assumed that you will go to those references for details since they were not mentioned. I had to cut things short a little since the topic is very lengthy. [sig][/sig]