Mike Dolt Enterprises
Mike Dolt Enterprises
User: richwaskowitz, Location: Shelby Twp. MI, near Detroit
Asked on: Wednesday, March 23, 2011 at 4:44 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:11 am EDT
Question: When fuse coordination (black-out prevention) is required between a control panel and its bus plug, even when putting FRS fuses in the plug and Js in the panel disconnect, the fuse in the bus plug should be 1.5 times the setting of the one in the panel. Does that mean that the feeder conductors need to be sized to the bus plug fuse or can they be sized for the load? For example: A panel with a 80 amp load might have a LPJ100 fuse in the main disconnect to allow for future expansion. If an FRS150 fuse is put in the bus plug, do the feeders need to go to 1/0?
Conductors can be sized for the load.
Fuse coordination for black-out prevention requires the fuse in the bus plug to be 1.5 times the setting of the fuse in the panel disconnect, even when using FRS fuses in the plug and Js in the panel disconnect.However, the feeder conductors do not need to be sized to the bus plug fuse. They can be sized for the load.In your example, a panel with an 80 amp load could have a LPJ100 fuse in the main disconnect to allow for future expansion. If an FRS150 fuse is put in the bus plug, the feeders do not need to go to 1/0. They can be sized for the 80 amp load, which would be #4 AWG copper conductors. Flag for review