Parallel Service Entry Conductors

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Dansos

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Hey guys we are replacing service entry wires that were stolen out of a 3P 240D system. It’s overhead drop and once through meter it lands on top of a 400A Main Breaker.
It appears that they had 500 Cu coming down to top of meter and then had 350 Cu running out of meter into main breaker. I am not sure exactly what was ran, but I DO KNOW that the load side of the meter had smaller wire then the line side, so that’s why I am assuming the 500 and 350.
First question: Is it legal to have 350 Cu powering a 400A main?????
Second question: I am not sure the breaker will accommodate 500 Cu into the lugs. They have double lugs on the line side of breaker (Siemens JXD63B400) so we were thinking of running parallels off the bottom of meter lugs. In a 3P Delta system, we DO NOT COUNT the neutral as a CCC, right? If I’m correct to that point, we could use 4/0AL from load side to breaker right?? Or can we not use 90° column for that?
Thanks in advance for any input and/or experience you guys have with this. It’s a tad out of my league in terms on common practice for this kind of stuff.
 
First question: Is it legal to have 350 Cu powering a 400A main????? No
.......DO NOT COUNT the neutral as a CCC, right? Likely you do not count it
we could use 4/0AL from load side to breaker right?? Lot of variables... What is the load, How long is the conduit and how many conductors are in the conduit.
Or can we not use 90° column for that? Only for derating
It’s a tad out of my league Yes
 
augie47 said:
First question: Is it legal to have 350 Cu powering a 400A main????? No
.......DO NOT COUNT the neutral as a CCC, right? Likely you do not count it
we could use 4/0AL from load side to breaker right?? Lot of variables... What is the load, How long is the conduit and how many conductors are in the conduit.
Or can we not use 90° column for that? Only for derating
It’s a tad out of my league Yes
Click to expand...
Thanks Augie.
Sorry I did not give more info on the characteristics of the electrical. It is a very large building that is going to be used to store vehicles of the new owners. Most of the original electric has been removed and/or is no longer being used. Owner is only going to be running lights and basic receptacles throughout the building.
The 400A main breaker panel has (1) 200A breaker that powers a load center across the room which controls all the lights inbuilding. That is the only breaker in the main panel right now.

As for determining size of parallels, the conduit run is approx 15’ from meter to main breaker. The load for the building is honestly not going to go above 100 amps. If we were to run parallels, the conduit would have 8 total wires running through it (2 per phase and 2 for neutral) 6CCC’s total right?
4/0 @ 90° = 205 x 2 = 410 x .8 = 328A
It is 4” RMC.

I am curious as to why it’s “likely” only 3 CCC’s in this system? Would the neutral ever be counted as a CCC in a delta system?
The only possible way I could see that being counted is if there were some large non linear loads.
 
Whether or not the neutral is a CCC doesn't change your calculation. You need at least 351 amps worth of conductor to land on the 400 amp OCPD using the next size up rule.
 
Sounds like there isn't much load....not sure about the specifics of pipe size and lug sizes and quantity, but you have many options if you use the next size up rule. Like infinity said you only need 351 amps of conductor to round up. You could do single 500 CU,. Or two sets of 3/0 CU or 250 Al (both would be ok even if these are in same pipe and you have to derate).
 
infinity said:
Whether or not the neutral is a CCC doesn't change your calculation. You need at least 351 amps worth of conductor to land on the 400 amp OCPD using the next size up rule.
Click to expand...
I’m sorry I wrote that response a little backwards. I understand that the CCC’s do not influence the calc. My question and/or confusion on that is when the neutral DOES become a CCC in a delta system.
 
Dansos said:
I’m sorry I wrote that response a little backwards. I understand that the CCC’s do not influence the calc. My question and/or confusion on that is when the neutral DOES become a CCC in a delta system.
Click to expand...
In my opinion the neutral of a 4 wire high leg delta system, is never a current carrying conductor for the purposes of ampacity adjustment.
 
don_resqcapt19 said:
In my opinion the neutral of a 4 wire high leg delta system, is never a current carrying conductor for the purposes of ampacity adjustment.
Click to expand...
What about for the 3 phase, 3-wire, corner grounded system mentioned in the OP?
 
Dansos said:
Thanks Augie.
Sorry I did not give more info on the characteristics of the electrical. It is a very large building that is going to be used to store vehicles of the new owners. Most of the original electric has been removed and/or is no longer being used. Owner is only going to be running lights and basic receptacles throughout the building.
The 400A main breaker panel has (1) 200A breaker that powers a load center across the room which controls all the lights inbuilding. That is the only breaker in the main panel right now.

As for determining size of parallels, the conduit run is approx 15’ from meter to main breaker. The load for the building is honestly not going to go above 100 amps. If we were to run parallels, the conduit would have 8 total wires running through it (2 per phase and 2 for neutral) 6CCC’s total right?
4/0 @ 90° = 205 x 2 = 410 x .8 = 328A
It is 4” RMC.

I am curious as to why it’s “likely” only 3 CCC’s in this system? Would the neutral ever be counted as a CCC in a delta system?
The only possible way I could see that being counted is if there were some large non linear loads.
Click to expand...
If your load calculations are less than 368 amps then you can go back with parallel 250 Al that has a 90c rating. That should fit in your 4" RMC. If you need the whole 400 amps, parallel 300 Al would get it done.
 
infinity said:
What about for the 3 phase, 3-wire, corner grounded system mentioned in the OP?
Click to expand...
That is not a neutral per the Article 100 definitions. I guess I should have looked at the OP When I see neutral and delta, I just assume it is a 4 wire high leg system.
The grounded conductor of a 3 wire corner grounded system is always a current carrying conductor for the purposes of ampacity adjustment.
 
Dansos said:
Thanks Augie.
Sorry I did not give more info on the characteristics of the electrical. It is a very large building that is going to be used to store vehicles of the new owners. Most of the original electric has been removed and/or is no longer being used. Owner is only going to be running lights and basic receptacles throughout the building.
The 400A main breaker panel has (1) 200A breaker that powers a load center across the room which controls all the lights inbuilding. That is the only breaker in the main panel right now.

As for determining size of parallels, the conduit run is approx 15’ from meter to main breaker. The load for the building is honestly not going to go above 100 amps. If we were to run parallels, the conduit would have 8 total wires running through it (2 per phase and 2 for neutral) 6CCC’s total right?
4/0 @ 90° = 205 x 2 = 410 x .8 = 328A
It is 4” RMC.

I am curious as to why it’s “likely” only 3 CCC’s in this system? Would the neutral ever be counted as a CCC in a delta system?
The only possible way I could see that being counted is if there were some large non linear loads.
Click to expand...
I'm sticking with a Delta with one winding center tapped for the neutral.
 
That breaker doesn’t seem to have an interchangeable rating plug, but may have been ordered from the factory with a lower rating plug. That may be why they reduced the wire size.
 
electrofelon said:
I didn't see " 3 wire" in the OP. I'm assuming it's 4 wire/high leg Delta but perhaps OP can clarify.
Click to expand...

Sorry I was reading this on my phone so I missed the part below. This wasn't from the OP but from post #3. So I'll stick with what I stated in post #11.


Dansos said:
As for determining size of parallels, the conduit run is approx 15’ from meter to main breaker. The load for the building is honestly not going to go above 100 amps. If we were to run parallels, the conduit would have 8 total wires running through it (2 per phase and 2 for neutral) 6CCC’s total right?
Click to expand...
 
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