Sizing wire/ ocpd for Line side of a Disconnect Switch

Status
Not open for further replies.

Bkratky

Member
Location
Houston tx usa
Heres my brief scenario, I have a 200 amp disconnect fed with 3/0 awg, I need to remove the 200 and add 3- 30 amp disconnects. I was going to set a gutter box, use several polaris taps, and take my 3/0awg down to 8awg ( sized X1.25 for continuous use) to come in to the line side of my disconnects. The only problem i can see is my Line side wire will be sized at # 8 awg (30AX1.25=#8awg) but im tapping off 3/0awg fed from a 200 amp breaker. so my load side will be protected by 30 amp fuses, but my line side will be over sized for 200 amps tapped to 8awg. where in the code can i reference why this can or cant be done?
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
Heres my brief scenario, I have a 200 amp disconnect fed with 3/0 awg, I need to remove the 200 and add 3- 30 amp disconnects. I was going to set a gutter box, use several polaris taps, and take my 3/0awg down to 8awg ( sized X1.25 for continuous use) to come in to the line side of my disconnects. The only problem i can see is my Line side wire will be sized at # 8 awg (30AX1.25=#8awg) but im tapping off 3/0awg fed from a 200 amp breaker. so my load side will be protected by 30 amp fuses, but my line side will be over sized for 200 amps tapped to 8awg. where in the code can i reference why this can or cant be done?

See 240.21(B).

I see no reason to make your tap conductors #8. #10 would be fine for a 30A tap.
 
Status
Not open for further replies.
Top