Individual Motor Disconnects

Status
Not open for further replies.
N

nhee2

Senior Member
Location
NH
I have a vendor supplied system which includes a listed control panel (starter panel). The panel has a 1000A MCB, which feeds (2) separate 250 HP soft starters and other ancillary components. There are individual fuses (3P) feeding each soft start internal to the panel, then motor circuit conductors would go from the panel to the motor. The driven loads (250 HP compressors) are in the vicinity of the starter panel - both are outdoors under separate canopies - they could be arranged to be within site of the panel.

I had not originally considered that disconnects would be needed for the compressors, but I don't know that this meets any of the exceptions to 430.112. Although the compressors are part of the same system, they would not be considered to be part of the same machine or device. They are outdoors - not 'in the same room' as described in 430.112(c).

- Is there any other section that would apply to allow me to NOT specify individual disconnect switches for each motor?
- In the event that I need disconnects, does 430.109(E) allow us to use a 400A switch (rated 200HP, vs. a 600 A /400 HP switch) provided it is marked to not operate under load?

Obviously a couple extra 400A switches adds cost and takes up some real estate that I am not sure we have.

Thanks.
 
Is it possible that you can meet 430.102(B) (2) Exception as allowed by (b) for industry with written LOTO ?

(In the '11 Code, the terminology controller disconnect "individually capable of being locked" sounds like it may prevent this but I have seen that approached differently depending on the AHJ)
(In the '14 Code I believe the term "individually" was dropped if that helps your discussion)
 
Last edited:
Actually, 430.102(B)(2) exception condition (a) or (b) might apply - the informational note lists motors rated in excess of 100hp as a possible example of increased hazards.

However in that case I still do not have 'an individual disconnecting means.....for each controller' as specified in 430.102(A), unless I am reading that section incorrectly to mean that each soft start needs its own disconnecting means.

Thanks for the response.
 
Status
Not open for further replies.
Top