Breaker/Wire Size

infinity said:
For example you can have a 150 circuit breaker with #1/0 going to the equipment and at the equipment you have a 200 amp disconnect with 200 amp fuses.
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A 150A OCP device upstream of and protecting a 200A OCP device? I see the reverse of this possible but do not understand the theory behind this application.
 
Existing equipment fed from new source?
Coordination where it is desired that the downstream device not operate except in extreme short circuits?
Use what was in the truck?
 
Sparky2791 said:
A 150A OCP device upstream of and protecting a 200A OCP device? I see the reverse of this possible but do not understand the theory behind this application.
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Where is the hazard, assuming that the conductors between the 150 a OCPD and the 200 amp OCPD are rated at least 150 amps? Of course the load in the 200 amp panel cannot exceed 150 amps.
 
don_resqcapt19 said:
Where is the hazard, assuming that the conductors between the 150 a OCPD and the 200 amp OCPD are rated at least 150 amps? Of course the load in the 200 amp panel cannot exceed 150 amps.
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I see your point but cannot think of an application where this would ever be needed. I would never do that and feed a panel w/ a 200A main in it (Infinity mentions feeding a disc. sw. w/ 200A fuses for equipment.) That is just asking someone to add more load than the 200A panel can handle because they did not check to see what it is actually fed with which is only 150A.
 
Sparky2791 said:
I see your point but cannot think of an application where this would ever be needed. I would never do that and feed a panel w/ a 200A main in it (Infinity mentions feeding a disc. sw. w/ 200A fuses for equipment.) That is just asking someone to add more load than the 200A panel can handle because they did not check to see what it is actually fed with which is only 150A.
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Regardless of whether or not it's a good design it is code compliant. If someone comes a long in the future and thinks that the panel feeder is actually good for 200 amps that's on them for not doing their homework.
 
Sparky2791 said:
I see your point but cannot think of an application where this would ever be needed. I would never do that and feed a panel w/ a 200A main in it (Infinity mentions feeding a disc. sw. w/ 200A fuses for equipment.) That is just asking someone to add more load than the 200A panel can handle because they did not check to see what it is actually fed with which is only 150A.
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Not say it is needed, but sometimes it is cheaper to buy a panel with a breaker package, including a main, than buying a MLO panel and breakers separately. Sometimes the main would be larger than the feeder circuit.
 
infinity said:
Regardless of whether or not it's a good design it is code compliant. If someone comes a long in the future and thinks that the panel feeder is actually good for 200 amps that's on them for not doing their homework.
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I suppose stupid is as stupid does applies here.;). I agree with your statements it is code compliant.
 
don_resqcapt19 said:
Not say it is needed, but sometimes it is cheaper to buy a panel with a breaker package, including a main, than buying a MLO panel and breakers separately. Sometimes the main would be larger than the feeder circuit
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I get it, does not mean I like it, but I get it. The almighty $$ rules in most cases, LOL
 
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