NEC Code lets me to splice a 700 ' 1/0 cable to 8 AWG to land it on a Panel Breaker?

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I'm proposing to run 700' run of 1/0 cable with 120 VAC single phase on it. At the service (supply) side I am proposing to splice it into 10 AWG or 12 AWG conductor so I can land it on a circuit breaker on a 120/240 VAC panel. At the load side, I want to be within a 2% voltage drop at 10 Amps.
Actually, this isn't my ideal. I wanted to use 120/480 VAC Transformers but I've been asked to try this to keep the cost down.

Does the NEC Code allow this? Does anyone know the specific section. Thanks!
 
Perfectly fine, the NEC doesn't care as long as the smallest conductor in the chain is sized for the OCPD.

Roger
 
roger said:
Perfectly fine, the NEC doesn't care as long as the smallest conductor in the chain is sized for the OCPD.

Roger
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And this is professional and I won't get laughed at for "jury rigging" .
Is their an industry standard splice connector that allows me mate a 12 AWG to 1 AWG wire that is highly regarded, such as Greenlee, etc.
I'm just being careful
 
Do a google search for Google search for Polaris lugs or Burndy and pick one that fits your situation.

Here's a Burndy that might work

You could also mount a pull box somewhere near the panel and splice there.

Roger
 
Installer said:
And this is professional and I won't get laughed at for "jury rigging" .
Is their an industry standard splice connector that allows me mate a 12 AWG to 1 AWG wire that is highly regarded, such as Greenlee, etc.
I'm just being careful
Click to expand...

Burndy makes a compression copper, in-line splice kit that may provide this range. It comes with a heat shrink sleeve that fits over the splice - you could make the connection within the panelboard near the breaker.
 
Don’t forget to upsize your equipment ground conductor to the same size as your phase and neutral conductors.
 
Another possibility that MAY save some money would be to run 240 for the 700 ft run, with a 240:120 transformer at the load end. That would cut your wire size in half, and a 1.5kVA transformer is not too large or expensive. It'd require the same number (3) of conductors.
 
Installer said:
I'm proposing to run 700' run of 1/0 cable with 120 VAC single phase on it. At the service (supply) side I am proposing to splice it into 10 AWG or 12 AWG conductor so I can land it on a circuit breaker on a 120/240 VAC panel. At the load side, I want to be within a 2% voltage drop at 10 Amps.
Actually, this isn't my ideal. I wanted to use 120/480 VAC Transformers but I've been asked to try this to keep the cost down.

Does the NEC Code allow this? Does anyone know the specific section. Thanks!
Click to expand...
10 amps @ 120 volts is only 1200VA. If you have a fixed load of no more than that, I would think 1.5kVA transformers may just possibly cost less, especially if your run of 1/0 is copper. You don't need extra overcurrent devices if transforming two wire primary to two wire secondary.
 
tkb said:
Don’t forget to upsize your equipment ground conductor to the same size as your phase and neutral conductors.
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No, you must increase your EGC by the same ratio as you increased your current carrying conductors, not to the same size as they are.
 
ggunn said:
No, you must increase your EGC by the same ratio as you increased your current carrying conductors, not to the same size as they are.
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It depends on the OCPD used for the 120 volt circuit. In this case if the circuit is 15, 20, or 30 amps (which requires an EGC the same size as the phase conductors) the EGC is increased at a ratio of 1 to 1 or the same size tkb stated.
 
infinity said:
It depends on the OCPD used for the 120 volt circuit. In this case if the circuit is 15, 20, or 30 amps (which requires an EGC the same size as the phase conductors) the EGC is increased at a ratio of 1 to 1 or the same size tkb stated.
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Correct.

Now take OP's same circuit, assuming copper conductors and put a 150 amp breaker at the beginning - then put a 15,20 or 30 amp breaker at the load end of that 1/0 and short run of 14,12 or 10 AWG to the load and you still have essentially same thing but can 6 AWG EGC instead of a 1/0 EGC with the feeder segment of this.

Totally makes sense doesn't it?
 
infinity said:
It depends on the OCPD used for the 120 volt circuit. In this case if the circuit is 15, 20, or 30 amps (which requires an EGC the same size as the phase conductors) the EGC is increased at a ratio of 1 to 1 or the same size tkb stated.
Click to expand...

Well, OK, but if the EGC is already the same size as the CCC's, increasing it by the same ratio means that it will still be the same size as the CCC's. The rule isn't different.
 
ggunn said:
No, you must increase your EGC by the same ratio as you increased your current carrying conductors, not to the same size as they are.
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Since the OP inferred that this was a 20 amp circuit, then the EGC would be the same size as the CCC, so since they are the same size the 1:1 ratio would mean that they would be the same size when increased for VD.
 
tkb said:
Since the OP inferred that this was a 20 amp circuit, then the EGC would be the same size as the CCC, so since they are the same size the 1:1 ratio would mean that they would be the same size when increased for VD.
Click to expand...
But if one ran a "feeder" for most the length of the circuit (with overcurrent protection that corresponds to the feeder conductor ampacity) and a smaller, short branch circuit at the load end, you have same length, you have same size current carrying conductors but can now reduce the EGC to whatever it says in T250.122 and that is code compliant.

They don't trust the 20 amp breaker to trip in reasonable time unless you also run a 1/0 EGC, but we can put a 150 amp breaker in there instead and reduce the EGC to 6 AWG. :blink:
 
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