Parallel Feeder to 2 Disos

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masselectrician

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Would it be a violation to feed two seperate 400A discos, which in turn feed two transformers, which each have their own panel, from one three pole 800A breaker? Assuming balancing was not an issue.
 
It could be done but the conductors will have to joined together at the disco end before being connected to the discos.
 
I may be missing something but from what I picture it would be permissible if the feeds to the 400 amp disconnects met the tap rules in 240.21.
 
That is the question we were debating today. Do we have to bring both sets into a can, join the two runs, then tap off to each disco so that each phase from both sets come into each disco. Just wondering if anything would prevent bringing one run into each disco directly.
 
masselectrician said:
Just wondering if anything would prevent bringing one run into each disco directly.
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You could do that only if those conductors would meet the tap rules for distance.

If the run is long and inside than no you will have to join them first.

I just recently had to tap the end of a 1600 amp feeder with a 400 and 800 fused switch, I had to buy four 7 port 750 Kcmil 'polaris' connectors to do it at just $140 per connector.

TheTool.jpg
 
Bob, I'm curious how you made the connections to the Polaris. Did you connect the lines to ports 1-4 and the loads to ports 5-7 or did you alternate line/load. I have never noticed a current rating on the connectors but always figured they were good for at least the rating of the maximum wire size. If all of the lines were connected to one end and all of the loads to the other end the middle of the connector would need to carry 1200 amps.
 
curt swartz said:
Did you connect the lines to ports 1-4 and the loads to ports 5-7
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Yes.

or did you alternate line/load.
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No


I have never noticed a current rating on the connectors but always figured they were good for at least the rating of the maximum wire size. If all of the lines were connected to one end and all of the loads to the other end the middle of the connector would need to carry 1200 amps.
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It's funny I contemplated this same thing the night we were doing the cut over but ended up figuring the unit must be rated for what the conductors could carry.
 
curt swartz said:
Bob, I'm curious how you made the connections to the Polaris. Did you connect the lines to ports 1-4 and the loads to ports 5-7 or did you alternate line/load. I have never noticed a current rating on the connectors but always figured they were good for at least the rating of the maximum wire size. If all of the lines were connected to one end and all of the loads to the other end the middle of the connector would need to carry 1200 amps.
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Quite intriguing subject. If determined by bus sizing as a "guide", the cross sectional area would have to be 1.2 in? Cu to carry 1200A at any point. Line-load staggered would definitely be the better approach.

Assuming a 2x1 out, the one would best be placed in the middle hole.
 
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Bob, I first want to state that I wasn't stating that you did anything wrong. I have seen these connectors used this way in the past but have always questioned how they should be connected. My gut feel was to alternate. I have not seen any instructions from NSI/Polaris. I just checked Ilsco's web site since they now makes a similar connector and below are the specifications.

  • Broad wire range: 750kcmil-14
  • UL Listed and CSA certified for 600 volts, 90?C
  • Dual rated for copper or aluminum conductor
  • Cold temperature rated to -45?C
  • High dielectric strength plastisol is chemical resistant
  • Black cover is UV rated
  • Removable port & screw plugs
  • Prefilled with De-ox
  • Per NEC Article 310-16 Allowable Ampacities are as follows: # 4 - 95 Amps, 1/0 - 170 Amps, 3/0 - 225 Amps, 250 - 290Amps, 350 - 350 Amps, 500 - 430 Amps, 750 - 535 Amps
  • Incoming and outgoing conductors must be staggered.
  • UL File E6207
 
iwire said:
I had seven ports, 4 IN, 3 OUT.
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...and of the three outs 2 went to one disco while one went to another... 2x1 out.

I also know from a months worth of recording that the entire load carried by these connector does not exceed 700 amps.
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I'm sure this info makes everyone more comfortable with your use of the connectors... but staggered is still the better approach. Don't you agree?

I know you don't like to agree with me, so I'll let you slide if you don't answer :D
 
Smart $ said:
but staggered is still the better approach. Don't you agree?
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I will go with 'it would not be worse.' :grin:

Quite honestly there where instructions with the each unit and they said nothing about what is required or expected as far as ins and outs. This tells me the units are designed to accommodate worst case loading conditions.


I know you don't like to agree with me, so I'll let you slide if you don't answer :D[/QUOTE]

LOL:grin:
 
curt swartz said:
Bob, I first want to state that I wasn't stating that you did anything wrong.
Click to expand...


I did not take it that way. :)



I just checked Ilsco's web site since they now makes a similar connector and below are the specifications.

  • Broad wire range: 750kcmil-14
  • UL Listed and CSA certified for 600 volts, 90?C
  • Dual rated for copper or aluminum conductor
  • Cold temperature rated to -45?C
  • High dielectric strength plastisol is chemical resistant
  • Black cover is UV rated
  • Removable port & screw plugs
  • Prefilled with De-ox
  • Per NEC Article 310-16 Allowable Ampacities are as follows: # 4 - 95 Amps, 1/0 - 170 Amps, 3/0 - 225 Amps, 250 - 290Amps, 350 - 350 Amps, 500 - 430 Amps, 750 - 535 Amps
  • Incoming and outgoing conductors must be staggered.
  • UL File E6207
Click to expand...

Well thats interesting.

I have one left I will have to check what brand I have.
 
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