Feeder Run Size

[Alwayslearningelec]

100A disconnect to panel is 2,000' away. Yes 2,000' away. That's odd in itself.

When calculating load it would obviosuly be based on the 200A panel *125%, correct? The I have the voltage drop issue. I'm asking because they are not showing feeder sizes and I'm curious. If I were to even include I would qualify.


EDIT: Sorry..they are showing 4 #4/0 in 2" RGS.


On a side not I'm note exactly sure what length reel would make sense or the max reel length. I would say 1000' or would it be less before a splice? It's fairly straight.

 

[augie47]

In real life you would base the calculation on the load/
If you have a 100 amp disconnect at the supply end, 100 is the largest number I would use.

 

[Alwayslearningelec]

In real life you would base the calculation on the load/
If you have a 100 amp disconnect at the supply end, 100 is the largest number I would use.

So not the 200a panel size?what if they added loads later on? But then the 100a disconnect wouldn't suffice.

 

[infinity]

The service disconnect has 40 amp fuses so that is the maximum current that should be used in the VD calculation.

 

[Alwayslearningelec]

The service disconnect has 40 amp fuses so that is the maximum current that should be used in the VD calculation.

Panel schedule says 200A but then this say 100A. Can you explain further the VD calculation? Is 4#4/0 correct as they show? Thanks

 

[Alwayslearningelec]

Can someone help with splicing parameters for 2000' run. I'd think I need at least one splice point. Thanks.

 

[infinity]

Panel schedule says 200A but then this say 100A. Can you explain further the VD calculation? Is 4#4/0 correct as they show?

The service disconnect has 40 amp fuses so the feeder load will not exceed 40 amps. According to my Southwire calculator using 40 amps the minimum conductor size for 2.82% VD is 600 kcmil copper.

 

[charlie b]

40 amps at 208 volts equates to just under 15 KVA. Try comparing the cost of 6000 feet (i.e., 2000 feet, 3 phase conductors) of 600 kcmil wire with the cost of the same distance of smaller wire (I have not yet done this VD calc) plus two 15 KVA transformers (one to step up to 480 volts and one to step back down to 208/120 volts).

 

[infinity]

40 amps at 208 volts equates to just under 15 KVA. Try comparing the cost of 6000 feet (i.e., 2000 feet, 3 phase conductors) of 600 kcmil wire with the cost of the same distance of smaller wire (I have not yet done this VD calc) plus two 15 KVA transformers (one to step up to 480 volts and one to step back down to 208/120 volts).

208 volts at 2000' is a terrible design.

 

[augie47]

Voltage Drop, for the most part, is not a Code mandated issue. Is someone specifying a maximum voltage drop ?
What type of load is involved ?

(and, in the end, as infinity states, terrible design..we have had some freeway readerboard feeders that long but they have always done stepup-step down as has been discussed here frequently.)

 

[LarryFine]

When calculating load it would obviosuly be based on the 200A panel *125%, correct?

No. Voltage drop is based purely on load current and feeder impedance.

 

[Alwayslearningelec]

Voltage Drop, for the most part, is not a Code mandated issue. Is someone specifying a maximum voltage drop ?
What type of load is involved ?

(and, in the end, as infinity states, terrible design..we have had some freeway readerboard feeders that long but they have always done stepup-step down as has been discussed here frequently.)

Yes it would make sense to run that long at 277v.

 

[d0nut]

40 amps at 208 volts equates to just under 15 KVA. Try comparing the cost of 6000 feet (i.e., 2000 feet, 3 phase conductors) of 600 kcmil wire with the cost of the same distance of smaller wire (I have not yet done this VD calc) plus two 15 KVA transformers (one to step up to 480 volts and one to step back down to 208/120 volts).

Or perhaps only one transformer if you can get the utility company to give you a 480V service.

 

[LarryFine]

Yes it would make sense to run that long at 277v.

Or higher.

 

[infinity]

Yes it would make sense to run that long at 277v.

I would use a 600 volt step up at the service and a 600-208Y/120 at the panel end.

 

[augie47]

If I didn't make a mistake in math.....
If you use a 40 amp load at 208 volts the 4/0 they show would give you a 5% voltage drop
The same 5% at 600 volt would require a #6

 

[Knightryder12]

Voltage Drop, for the most part, is not a Code mandated issue. Is someone specifying a maximum voltage drop ?
What type of load is involved ?

(and, in the end, as infinity states, terrible design..we have had some freeway readerboard feeders that long but they have always done stepup-step down as has been discussed here frequently.)

You are correct, it is not in the NEC, but it is in the Energy Code if the project is in a location that requires it to be followed.

 

[augie47]

You are correct, it is not in the NEC, but it is in the Energy Code if the project is in a location that requires it to be followed.

I keep forgetting that as none of the jurisdictions that I deal with are enforcing that. Thanks.

Which energy code now addresses voltage drop ??

 

[Knightryder12]

I keep forgetting that as none of the jurisdictions that I deal with are enforcing that. Thanks.

Which energy code now addresses voltage drop ??

I think it is in Section C405 of of IEC.