caryj
Member
- Location
- Seattle, WA
So here is the situation:
An existing MCC bucket is a 250A fused switch.
I want to install a new Package Roof Top Unit, fed by this 250A feed and 250A wire and fused down to the necessary 175A. Can I install a 200A rated disconnect fed from 250A feed?
With the 175A fuses, there is no potential of more than 175A so the 200A rated parts and pieces of the disconnect are not in danger of seeing a normal condition load of more than 200A. And for that matter, the terminals of the disconnect will not accept fuses greater than 200A.
I know I can install 200A fuses in the MCC or a bigger disconnect, but do I have to? It seems that the 175A fuses are protecting the downstream wires as well as the disconnect.
What do you think?
An existing MCC bucket is a 250A fused switch.
I want to install a new Package Roof Top Unit, fed by this 250A feed and 250A wire and fused down to the necessary 175A. Can I install a 200A rated disconnect fed from 250A feed?
With the 175A fuses, there is no potential of more than 175A so the 200A rated parts and pieces of the disconnect are not in danger of seeing a normal condition load of more than 200A. And for that matter, the terminals of the disconnect will not accept fuses greater than 200A.
I know I can install 200A fuses in the MCC or a bigger disconnect, but do I have to? It seems that the 175A fuses are protecting the downstream wires as well as the disconnect.
What do you think?