What gauge wire?

[SoilSaver]

I'm running power out to a small barn. I'm running from a junction box on the outside of the house. It's about a 125-150' run. I will only be running a couple fluorescent lights and half a dozen outlets. Won't ever be using anything that draws too much power. The biggest thing will be a 250w heat lamp. Any suggestions on what gauge wire I'd need to make the run out there would be appreciated.

Thanks in advance

 

[theoldwizard1]

Despite what you are saying, this IS a case where overkill is a good thing ! You really want 240V out there, even if you have no plans on using it. 10/3 UF-B at an absolute minimum, but 8/3 UF-B would be better.

 

[SoilSaver]

Thanks theoldwizard1 I appreciate the insight. Any other ideas are welcome as well.

 

[wyliesdiesels]

Yes at that distance, youre gonna need #8 to keep the voltage drop below 3% with a 15a load.

 

[SoilSaver]

Appreciate it gents. Looks like 8 gauge it is.

 

[Norcal]

The use of UF cable is not compliant with 250.122(B), when oversizeing the ungrounded conductor the grounding conductor must be increased in size also, the grounding conductor is only 10 AWG, with 6 & 8 AWG UF cables, which is fine when used at 50 & 40A.

250.122(B)

Increased In Size. Where ungrounded conductors are increased in size from the minimum size that has sufficient ampacity for the intended installation, wire-type equipment conductors, where installed, shall be increased in size proportionately according to the circular mil area of the ungrounded conductors. 2014 edition NEC

The bold text was highlighted in the original text.

 

[pattenp]

The use of UF cable is not compliant with 250.122(B), when oversizeing the ungrounded conductor the grounding conductor must be increased in size also, the grounding conductor is only 10 AWG, with 6 & 8 AWG UF cables, which is fine when used at 50 & 40A.

250.122(B)

Increased In Size. Where ungrounded conductors are increased in size from the minimum size that has sufficient ampacity for the intended installation, wire-type equipment conductors, where installed, shall be increased in size proportionately according to the circular mil area of the ungrounded conductors. 2014 edition NEC

The bold text was highlighted in the original text.

I believe that section is being misinterpreted. The intent is when using single conductors if the ungrounded conductors are increased over what is actually needed the the EGC also needs to be increased, this is so you don't end up with mismatched ungrounded conductors and EGC. To me this means if I have a 20A circuit that would normally need #12 and I decide to increase the ungrounded conductors to #10's then I also need to increase the EGC to a #10 and not leave the EGC as a #12, even though a #12 is fine for 20A. But the issue is that someone could come along and now put 30A breaker on the circuit and now the #12 EGC is too small. When using a multiconductor cable the EGC is already sized to ampacity of the cable. If you read the end of 250.122 (A) that is about the EGC in a multiconductor cable. Some additional wording was adding in 2014 but I think they need a person who can write in plain English so code makes sense.

Edit: #10 Cu EGC is good to 60 amps.



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[Speedy Petey]

I believe that section is being misinterpreted. The intent is when using single conductors if the ungrounded conductors are increased over what is actually needed the the EGC also needs to be increased, this is so you don't end up with mismatched ungrounded conductors and EGC. To me this means if I have a 20A circuit that would normally need #12 and I decide to increase the ungrounded conductors to #10's then I also need to increase the EGC to a #10 and not leave the EGC as a #12, even though a #12 is fine for 20A. But the issue is that someone could come along and now put 30A breaker on the circuit and now the #12 EGC is too small. When using a multiconductor cable the EGC is already side to ampacity of the cable. If you read the end of 250.122 (A) that is about the EGC in a multiconductor cable. Some additional wording was adding in 2014 but I think they need a person who can write in plain English so code makes sense.

Edit: #10 Cu EGC is good to 60 amps.



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FULLY agree. ANY inspector who would pull this one is looking for something to fail and looking for an argument, and he'd get one from me.

 

[wyliesdiesels]

I believe that section is being misinterpreted. The intent is when using single conductors if the ungrounded conductors are increased over what is actually needed the the EGC also needs to be increased, this is so you don't end up with mismatched ungrounded conductors and EGC. To me this means if I have a 20A circuit that would normally need #12 and I decide to increase the ungrounded conductors to #10's then I also need to increase the EGC to a #10 and not leave the EGC as a #12, even though a #12 is fine for 20A. But the issue is that someone could come along and now put 30A breaker on the circuit and now the #12 EGC is too small. When using a multiconductor cable the EGC is already side to ampacity of the cable. If you read the end of 250.122 (A) that is about the EGC in a multiconductor cable. Some additional wording was adding in 2014 but I think they need a person who can write in plain English so code makes sense.

Edit: #10 Cu EGC is good to 60 amps.

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[Norcal]

I see no exception for cable assemblies listed if you know where it is located, please feel free to post it. It would not upset me in the least 'cause that section can cause a lot of problems.

 

[pattenp]

I see no exception for cable assemblies listed if you know where it is located, please feel free to post it. It would not upset me in the least 'cause that section can cause a lot of problems.

That's the problem. The code is not clear in my opinion. I believe the stipulation for the EGC for multiconductors in 250.122 (A) to meet the requirements of Table 250.122 indicates that the section intention was to cover the install of individual conductors, not cables. That's why I believe the multiconductor cable paragraph was added in 2011.