Fused Disconnect, fuse too small?

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Npstewart

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I have 400A main disconnect here shown in the picture. The two fuses on the left are 400A, the one on the right is 200A Any explanation for this? I had to compress this picture so it would fit in the forum.
 
lol, thats too funny. I guess you could be right though.. The one with the 200A fuse, has a 3/0 wire running to it. Im not sure what the other wire sizes are, but they are definitely larger, they look like they are either 500's or 600's. The enclosure label says its a 400A 3phase disc. Anyone else have a suggestion. I posted a post yesterday that was pretty hot. It was titled "3 phase breaker in single phase panel" this is the same building. This is the main that is feeding a disconnect which feeder the panel.
 
From the picture it looks like smaller conductors on the load side so they would be providing OCP for the smaller conductor. Probably has a small 3ph load or a single 3ph piece of equipment.
 
What is the system voltage? The use of a smaller conuctor and fuse for the wild leg is common on 3 phase 240/120 volt 4 wire systems.
 
Npstewart said:
Any explanation for this?
Click to expand...
Yep. It's what's usually done when you have a single disco on a high-leg Delta, probably an open Delta. Can you find the transformers?

Today, the high leg would be in the center terminal, but that looks line an original installation.
 
It sure look like oringaly set up for open delta set up some case close delta { I doubt it due the size of conductor is a dead giveaway }

So therefore if you have legit wye transfomer on secondary side then it may be a good idea to replace the breaker box with triphase set up and run in triphase format.

Look at the transfomer nameplate I am pretty sure it was replace sometime back unless you still have oringal unit there.

Merci,Marc
 
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