Grounding

normbac

Senior Member
I am installing a 208 volt 3 phase panel 1000 ft from main panel it is for a 60 amp 3 phase motor load I was going to run paralell 4/0 AL question is 2/0 AL egc the correct size. Would it be a better design to just use a 4/0 as a neutral with no egc panel will be installed in a shipping container used for storage out in an open field. TIA
 

GoldDigger

Moderator
Staff member
If you are past the service disconnect, there is no way you can avoid running both a grounded conductor (neutral) and an EGC.
If you are able to run a separate set of service conductors from the line side of the main disconnect you must run just a single grounded conductor.

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infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I am installing a 208 volt 3 phase panel 1000 ft from main panel it is for a 60 amp 3 phase motor load I was going to run paralell 4/0 AL question is 2/0 AL egc the correct size. Would it be a better design to just use a 4/0 as a neutral with no egc panel will be installed in a shipping container used for storage out in an open field. TIA
If the load is only 3? couldn't you delete the neutral and just have an EGC?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I am installing a 208 volt 3 phase panel 1000 ft from main panel it is for a 60 amp 3 phase motor load I was going to run paralell 4/0 AL question is 2/0 AL egc the correct size. Would it be a better design to just use a 4/0 as a neutral with no egc panel will be installed in a shipping container used for storage out in an open field. TIA
according to the southwire VD calculator

1 conductors per phase utilizing a #250 Aluminum conductor will limit the voltage drop to 4.95% or less when supplying 60.0 amps for 1000 feet on a 208 volt system.
For Engineering Information Only:
205.0 Amps Rated ampacity of selected conductor
0.09 Ohms Resistance (Ohms per 1000 feet)
0.041 Ohms Reactance (Ohms per 1000 feet)
10.4 volts maximum allowable voltage drop at 5%
10.275. Actual voltage drop loss at 4.95% for the circuit
0.9 Power Factor
I don't think you need a N if it is not being used at the end but you do need an EGC.

Lots of wire. Have you considered running 480 to reduce the wire size instead of 208?
 
Last edited:

normbac

Senior Member
according to the southwire VD calculator



I don't think you need a N if it is not being used at the end but you do need an EGC.

Lots of wire. Have you considered running 480 to reduce the wire size instead of 208?
Need minimum 200 volts at end so #250 would be an issue
Main panel is 120/208 so no 480 available
there are feed thru lugs off 200amp main
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Wouldnt he want to consider the VD from the starting current, not just the FLA of the motor? There must be a "rule of thumb" for this? Like Petersonra said, maybe you should price out a 480 transformer on each end.
Or put a 208/480V xfmr at the source and change the motor to be 480 at the other end.
 

bob

Senior Member
Location
Alabama
2/0 is not the correct size for the EGC. A normal 60 amp would be #4 AL + #8 EGC. Since you are increasing
the conductor size from #4 AL to 2 - 4/0 AL, the EGC must be increased by the same percentage. It appears that
the EGC may require 2 - 4/0 AL. You need to check this out using the circular mils of the conductors.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
2/0 is not the correct size for the EGC. A normal 60 amp would be #4 AL + #8 EGC. Since you are increasing
the conductor size from #4 AL to 2 - 4/0 AL, the EGC must be increased by the same percentage. It appears that
the EGC may require 2 - 4/0 AL. You need to check this out using the circular mils of the conductors.
you cannot use parallel conductors for the egc.
 
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