Full size taps

[shockerz]

I have a 800 amp main cb fed by paralleled 500 mcm cu. There are various panels fed from lugs on the bottom of the cb. Four of the panels are to far ( more than 10'). I need to re feed these panels. I want to come off the main cb lugs with paralleled 500 mcm cu about 5' and tap off of these conductors to feed the 3-125 amp and 1-200 panels Is this code (2008) compliant? I am not sure because of art. 240.4b

 

[tkb]

I have a 800 amp main cb fed by paralleled 500 mcm cu. There are various panels fed from lugs on the bottom of the cb. Four of the panels are to far ( more than 10'). I need to re feed these panels. I want to come off the main cb lugs with paralleled 500 mcm cu about 5' and tap off of these conductors to feed the 3-125 amp and 1-200 panels Is this code (2008) compliant? I am not sure because of art. 240.4b

You need to look at 240.21(B).

The parallel 500 kcmil conductors are not considered a tap if they are fed from an 800 amp OPD.

 

[infinity]

I have a 800 amp main cb fed by paralleled 500 mcm cu. There are various panels fed from lugs on the bottom of the cb. Four of the panels are to far ( more than 10'). I need to re feed these panels. I want to come off the main cb lugs with paralleled 500 mcm cu about 5' and tap off of these conductors to feed the 3-125 amp and 1-200 panels Is this code (2008) compliant? I am not sure because of art. 240.4b

Sounds fine to me. You will have parallel 500 kcmil condcutors on the load side of the 800 amp CB and you will tap those 500's with various size tap conductors?

 

[tkb]

Sounds fine to me. You will have parallel 500 kcmil condcutors on the load side of the 800 amp CB and you will tap those 500's with various size tap conductors?

As long as his taps to the other panels are not over 10' long.
If they are over 10' and less than 25' long then they would have to be a minimum of 1/3 of the 800 amp feeder.
Also all of his panels need to be MCB.

 

[infinity]

Sounds fine to me. You will have parallel 500 kcmil condcutors on the load side of the 800 amp CB and you will tap those 500's with various size tap conductors?

As long as his taps to the other panels are not over 10' long.
If they are over 10' and less than 25' long then they would have to be a minimum of 1/3 of the 800 amp feeder.
Also all of his panels need to be MCB.

I agree. I meant to also say that he would need to follow the 10' and 25' tap rules.

 

[kwired]

I agree. I meant to also say that he would need to follow the 10' and 25' tap rules.

The tap device must include both of the 500's and the tap conductor. If you only tap onto a single 500 then you have a tap conductor supplying another tap, which is not allowed no matter what distances are involved.

 

[tkb]

I have a 800 amp main cb fed by paralleled 500 mcm cu. There are various panels fed from lugs on the bottom of the cb. Four of the panels are to far ( more than 10'). I need to re feed these panels. I want to come off the main cb lugs with paralleled 500 mcm cu about 5' and tap off of these conductors to feed the 3-125 amp and 1-200 panels Is this code (2008) compliant? I am not sure because of art. 240.4b

The 500's need to be paralled on both ends to be considered parallel conductors.
Also how are you making the connection to the breaker? Are there seperate lugs for each wire?

 

[shockerz]

The tap device must include both of the 500's and the tap conductor. If you only tap onto a single 500 then you have a tap conductor supplying another tap, which is not allowed no matter what distances are involved.

Yes I will be tapping
both ( paralelled) with stacked lugs on the cb and on the tap. The tap lug will be 2- 500, 1-3/o cu and 3- 1/0 cu

 

[infinity]

Yes I will be tapping
both ( paralelled) with stacked lugs on the cb and on the tap. The tap lug will be 2- 500, 1-3/o cu and 3- 1/0 cu

Are all of these taps 10' or less?

 

[tkb]

Are all of these taps 10' or less?

If the tap is longer than 10', the minimum size conductor that can be tapped to an 800 amp OPD is 300 kcmil (or parallel 1/0).
Can that tap terminate to a 100 amp MCB panel? (assuming the lugs will accept the wire size)

 

[mark32]

I'm confused

I'm confused

I have no experience with such installs so let me try to visualize this scenario: This 800a breaker has multiple terminations for each phase, so these parallelled 500 mcm conductors (Along with neutral) leave this breaker and enclosure and enter a trough. From there we tap each of these conductors, (Four taps on each) and feed three 125a panels and one 200a panel which is accomplished as follows: Conductor sizes aside, each panel needs parallelled feeders so each of these panels, assuming they receive all three phases, receive 6 ungrounded conductors, plus another two for the neutral. Is all this correct? That can't be right at all, maybe tap each 500 twice and each panel gets three ungrounded conductors and one neutral conductor, that sounds better, right?

 

[infinity]

I have no experience with such installs so let me try to visualize this scenario: This 800a breaker has multiple terminations for each phase, so these parallelled 500 mcm conductors (Along with neutral) leave this breaker and enclosure and enter a trough. From there we tap each of these conductors, (Four taps on each) and feed three 125a panels and one 200a panel which is accomplished as follows: Conductor sizes aside, each panel needs parallelled feeders so each of these panels, assuming they receive all three phases, receive 6 ungrounded conductors, plus another two for the neutral. Is all this correct? That can't be right at all, maybe tap each 500 twice and each panel gets three ungrounded conductors and one neutral conductor, that sounds better, right?

I believe that he is planning on doing it that way. The question that remains is how long are the tap conductors. If they're over 10' then the 25' rule will come into play requiring the tap conductors to be at least 1/3 the ampacity of the 800 amp OCPD.

 

[kwired]

I have no experience with such installs so let me try to visualize this scenario: This 800a breaker has multiple terminations for each phase, so these parallelled 500 mcm conductors (Along with neutral) leave this breaker and enclosure and enter a trough. From there we tap each of these conductors, (Four taps on each) and feed three 125a panels and one 200a panel which is accomplished as follows: Conductor sizes aside, each panel needs parallelled feeders so each of these panels, assuming they receive all three phases, receive 6 ungrounded conductors, plus another two for the neutral. Is all this correct? That can't be right at all, maybe tap each 500 twice and each panel gets three ungrounded conductors and one neutral conductor, that sounds better, right?

You lost me with your intent of "taping each 500". Let me explain in a little better detail what I mentioned earlier.

To make a tap from paralleled conductors your tap must connect to both the parallel conductors and the tap conductor.

In the scenario here the parallel 500's are joined together at each end to effectively make one 800 amp conductor. If you connect a tap off that 800 amp conductor you must connect the tap to both halves of the 800 amp conductor.

If you connect the tap to only one of the 500's then you effectively connected to a tap and not the 800 amp conductor.

If your tapped conductor happens to be paralleled conductors then you would need all elements of the feeder and all elements of the tap conductor in the same tap connection device.

Hope this helps.

 

[mark32]

Thank you kwired and infinity, now we're getting somewhere. The thought of joining the 500's at the end didn't come to mind. So, to make this tap, it would be easiest to use a Polaris type connector with, in this case, six terminals. Two for the 500's and one each for the four panels, sound good?

 

[kwired]

Thank you kwired and infinity, now we're getting somewhere. The thought of joining the 500's at the end didn't come to mind. So, to make this tap, it would be easiest to use a Polaris type connector with, in this case, six terminals. Two for the 500's and one each for the four panels, sound good?

Now you got it.:thumbsup: