art. 409

[lundell]

If you have a control panel with components with different sccr's I understand that the lowest rating sets the rating for the control panel, but do you need current limiting devices to even out the higher rated units.

 

[jim dungar]

Re: art. 409

I am not sure I understand your question.

I belive you are asking if there is a problem having devices with different SCCR in the same panel. As long as the available fault current does not exceed the lowest rated device, higher rated ones are not an issue.

 

[lundell]

Re: art. 409

Yeah, That is what I was trying to get at.
It is a panel with
Breaker 10 kA
2 Manual motor protectors 50 kA each
2 contactors 5 kA each
So by this the panel would have a 5kA sccr correct?
Dave Lundell

 

[jim dungar]

Re: art. 409

Yes.

However it is likely there is a series rating available (assuming the MCP and contactor are from the same manufacturer), where the manual motor protector has been tested to protect the contactor for a combined rating in excess of the 5KA. This is a standard application under UL 508.


edit: spelling

[ July 11, 2005, 03:22 PM: Message edited by: jim dungar ]

 

[lundell]

Re: art. 409

Yes, I see in the instruction sheet that they are listed for 50kA sccr as long as you use the manufacturers link module and base plate.
Thanks