Minimum Wire Size for Distribution

[Dale Hayes]

A distribution lug is fastened at the load side of a 450Amp fuse (see my attached drawing).

What is the minimum wire size I can use for the (7) 75C conductors located between the load side of the 450Amp fuse and the line side of the (7) 60Amp branch fuses? Can I use 4GA 75C wire?

 

[LEO2854]

A distribution lug is fastened at the load side of a 450Amp fuse (see my attached drawing).

What is the minimum wire size I can use for the (7) 75C conductors located between the load side of the 450Amp fuse and the line side of the (7) 60Amp branch fuses? Can I use 4GA 75C wire?

If you are using copper you can use #6 Table 310.16 #4 aluminum.

 

[david luchini]

It looks to me as if you a describing feeder taps, per 240.21(B). If the taps conductors does not exceed 10', then the tap conductor ampacity must be at least 60A. #4 AWG would be OK at 75 deg. #6 AWG would be OK at 75 deg. If the tap conductors are over 10' but not over 25', then the minimum required ampacity would be 150A.

It also appears that you also have tap conductors on the load side of the 800A fuses. The 2 sets of #3/0 to each of the 450A fuses would be in violation of 240.21(B)(1) or (2).

 

[augie47]

I agree with David on both counts.

 

[Dale Hayes]

Tapping a Tap?

Tapping a Tap?

SCR power controllers are often provided with power distribution lugs with multiple holes so that multiple crimp lugs may be utilized for power distribution to muliple circuits. Are these multiple circuits connections at the load side of a SCR power controller considered tapping a tap?

 

[Dale Hayes]

Attachment

Attachment

Attached is a revised drawing showing the (2) SCR power controllers with (2) mutiple circuits at the load side of each SCR.