How would you do this?

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chevyx92

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VA BCH, VA
Will need to tap buss bar of 2500A 208V main gear. Gear is old and only has (3) racking breakers and they are all used and can't reconfigure them. That's leaves us with tapping the buss bar. Only problem is we only need a 3P 200A feeder to a transformer. According to the 25FT tap rules, using tap conductors sized at 1/3 of ampacity, we would need parallel 600 kcmil CU with 350 CU EGC. How in the world would you terminate parallel 600 CU in a 200A 3P fused disconnect?! I say you can't, and probably can't terminate in a 600V 400A fused disconnect either! I need so opinions here. I would hate to have to set a 600A disconnect and then fuse it down but that may be the only way to do this? What do you think? Any other options?
 
david said:
Have you considered a 10 Ft Tap?
Click to expand...

We have. The only possible scenario for that would be to mount a fused disconnect on the side of the gear. There is absolutely no room on the wall to mount a disconnect. We were going to use the 25FT tap rule and mount disconnect outside.
 
chevyx92 said:
We have. The only possible scenario for that would be to mount a fused disconnect on the side of the gear. There is absolutely no room on the wall to mount a disconnect. We were going to use the 25FT tap rule and mount disconnect outside.
Click to expand...
Is the existing gear the service equipment? If so the new disconnect will have to be "grouped" with the existing service disconnects.
 
Short piece of Buss Duct with a tap box and a 200 amp fused buss plug.

JAP>
 
chevyx92 said:
Will need to tap buss bar of 2500A 208V main gear. Gear is old and only has (3) racking breakers and they are all used and can't reconfigure them. That's leaves us with tapping the buss bar. Only problem is we only need a 3P 200A feeder to a transformer. According to the 25FT tap rules, using tap conductors sized at 1/3 of ampacity, we would need parallel 600 kcmil CU with 350 CU EGC. How in the world would you terminate parallel 600 CU in a 200A 3P fused disconnect?! I say you can't, and probably can't terminate in a 600V 400A fused disconnect either! I need so opinions here. I would hate to have to set a 600A disconnect and then fuse it down but that may be the only way to do this? What do you think? Any other options?
Click to expand...

I think the first question would be can you even do a bus tap. Many AHJs would not accept this without a field evaluation by an NRTL.
 
chevyx92 said:
Will need to tap buss bar of 2500A 208V main gear. Gear is old and only has (3) racking breakers and they are all used and can't reconfigure them. That's leaves us with tapping the buss bar. Only problem is we only need a 3P 200A feeder to a transformer. According to the 25FT tap rules, using tap conductors sized at 1/3 of ampacity, we would need parallel 600 kcmil CU with 350 CU EGC. How in the world would you terminate parallel 600 CU in a 200A 3P fused disconnect?! I say you can't, and probably can't terminate in a 600V 400A fused disconnect either! I need so opinions here. I would hate to have to set a 600A disconnect and then fuse it down but that may be the only way to do this? What do you think? Any other options?
Click to expand...

What size Xfmr are you feeding that requires a 200 Amp Feeder?

JAP>
 
chevyx92 said:
We have. The only possible scenario for that would be to mount a fused disconnect on the side of the gear. There is absolutely no room on the wall to mount a disconnect. We were going to use the 25FT tap rule and mount disconnect outside.
Click to expand...

+1 for mounting on side of gear, with a chase nipple into the main gear.

if you need it to face forward, use a myers hub for a bit of standoff, with a chase nipple.
to support it, i'd go to a sheet metal shop, and have them bend a piece of 10 guage
appropriately sized for the switch, and put a couple angles on it so it won't flex.
 
jap said:
In that case cant you bump the disconnect to a 400 amp and the primary fuse size to 225?

JAP>
Click to expand...

We could. Heck if we sized to the 250% we could put an 800A disconnect with 700A fuses. Just overkill. Waste of resources and money. We are probably going to mount it on the side of the gear and use the 10ft tap rule with 250 KCMIL CU to a 200A disconnect.
 
chevyx92 said:
We could. Heck if we sized to the 250% we could put an 800A disconnect with 700A fuses. Just overkill. Waste of resources and money. We are probably going to mount it on the side of the gear and use the 10ft tap rule with 250 KCMIL CU to a 200A disconnect.
Click to expand...

If that's the case, why ask for opinions.
You asked for opinons of how to terminate large wire in a small disconnect.
That was one opinion.

JAP>
 
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