another tap rule question

[petersonra]

can I change the size of a tap wire along the way?

what I have is a CB that has a lug on it that takes nothing smaller than a 300KCM. It feeds another breaker that takes nothing larger than a 3/0.

i was thinking some kind of connector to splice a smaller wire to the larger wire. Maybe just a couple ring lugs.

i don't see a specific prohibition on it.

 

[david]

Sounds like you are asking if you can tap a feed(er)

 

[petersonra]

Sounds like you are asking if you can tap a feed(er)

the wire involved is a tap that starts at a 1600A breaker and goes to a smaller breaker.

 

[david]

In general you cannot tap a tap
But if you start at a 1600 amp breaker with 300 MCM and splice 3/0 to the 300 MCM and land that to the load side breaker apply the rules for a 3/0 tap from 1600 amp over current protection

 

[petersonra]

In general you cannot tap a tap
But if you start at a 1600 amp breaker with 300 MCM and splice 3/0 to the 300 MCM and land that to the load side breaker apply the rules for a 3/0 tap from 1600 amp over current protection

that was my thinking initially, but I figured it did not hurt to run it by some other people.

the tap is only a few feet long, and never leaves the enclosure it starts in, so I am clean there.

I might be able to just get a ring lug that will fit on the smaller Cb with the bigger wire, which is probably a better option anyway. but it annoys me to throw out the terminals that come with breakers. I try to buy them without the terminals and it takes like 4 extra weeks to get them and some times costs more than when they come with the terminals.

 

[david]

Just to be clear my thinking is you would have to treat the total length from the 1600 amp supply to the load side over-current based on the smallest conductor in your case 3/0

 

[petersonra]

Just to be clear my thinking is you would have to treat the total length from the 1600 amp supply to the load side over-current based on the smallest conductor in your case 3/0

The more I think about it the more I realize I should just bite the bullet and buy lugs for the larger size wire. Cobbling it up to try and use the terminals the Cb comes with is more trouble than it is worth.